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What is the sustained impact of master's programs in reproductive science and medicine in meeting the growing global demand for expertise in this field? This study provides quantitative data supporting the value of master's degree programs in providing students with educational experiences to meet the increasing demands for a well-trained workforce of reproductive scientists. Master's programs focused on reproduction-ranging from animal science, clinical embryology, and reproductive health and biology-are expanding around the globe, providing students with a degree beyond the bachelor's or its equivalent and are an alternative or bridge to other advanced degrees. However, the impact of these programs in creating a well-trained next generation of reproductive scientists to support workforce needs and advance the field has not been systematically investigated. We performed a web search to define the landscape of master's programs offered across the globe. We also convened a meeting (Global Perspectives: A Think Tank for MS Programs in Reproductive Science and Medicine at Northwestern University on 24-25 June 2024) to establish a network between four master's programs (two in the United States and two in Europe), including the Master at Northwestern University (USA), at University of Dundee (United Kingdom), at Colorado State University (USA), and at the University of Murcia (Spain). These programs are established at public and private institutions, are varied with respect to class size and duration, and span focus areas ranging from veterinary to human reproductive health to Assisted Reproductive Technologies (ART). We obtained and analyzed enrollment and outcome data from the four featured master's programs to determine the profile of students who pursue these master's degrees in reproductive science and determine how they contribute to the field post-degree. The study relied on self-reported data from each participating program. The programs were selected because they represent a cross-section of established master's programs in reproduction that have collectively trained almost 1000 students since 2004. We analyzed enrollment and outcome data from these four established master's programs. Programs reported on student outcomes post-degree, including job categories, job titles, employers, and other impact (e.g. publications, awards and honors, and grants and independent funding). Master's programs in reproduction and related fields are on the rise, with the number of programs having almost doubled from 73 in 2022 to 145 in 2025. The four featured programs reported on at least 9 years of retrospective data. The University of Murcia program started in 2004, Colorado State University in 2013, University of Dundee in 2014, and Northwestern in 2016. To date, these programs have trained 366, 210, 244, and 108 individuals, respectively, with average class sizes for each program ranging between 12 and 22 students. Most students across programs (81% cumulatively) are female. The programs based in the USA primarily attract US students, whereas the programs in the United Kingdom and Spain have a more global footprint. Students matriculate into programs with academic backgrounds in life sciences and related fields and have obtained prior degrees in broadly defined fields including biology, chemistry, animal sciences, and medicine. After students complete their master's degrees, they are generally continuing within the reproductive science and medicine pipeline with careers spanning: advanced training (e.g. PhD, MD, and DVM programs), clinical careers (e.g. embryology and andrology), research careers (e.g. scientist or faculty), and careers in industry and education. Our study is limited to four master's programs that were invited to the Global Perspectives: A Think Tank for MS Programs in Reproductive Science and Medicine meeting. The analysis performed here can serve as a basic template for tracking student profiles and outcomes across all existing programs, so that we can glean a more wholistic understanding of the impact of master's degrees programs in reproductive science and medicine. This study provides quantitative data supporting the value of master's degree programs in providing students with educational experiences to meet the increasing demands for a well-trained workforce of reproductive scientists. This work lays the foundation for establishing a formal consortium of master's programs in reproductive science whereby prospective data can be collected in a standardized way across programs, alumni outcomes tracked, and an educational network created. This could be of value in disciplines where there is an increasing trend toward accreditation and adherence to legal frameworks, such as reproductive medicine and embryology. This work was supported by institutional funds from the Center for Reproductive Science, the Thomas J. Watkins Endowment, and the Department of Obstetrics and Gynecology at Northwestern University (F.E.D.) and the Makowski Family Endowment, Department of Obstetrics and Gynecology, CU Anschutz School of Medicine (T.R.K.). C.L.R.B. is Co-Editor-in-Chief of Human Reproduction; he is a faculty member and deputy program lead for one of the courses discussed in this article (Dundee) for which salary is paid by the University of Dundee. All other authors have no conflicts of interest to declare. Not applicable.
Understanding how organisms allocate energy across competing physiological demands is central to predicting responses to environmental variation. In seasonal environments, shifts in resource availability and activity impose dynamic constraints on energy storage, maintenance and reproduction. Here, we investigated seasonal changes in body composition in the tegu lizard Salvator merianae using the minimally invasive dual-energy X-ray absorptiometry (DEXA) technique. After DEXA validation against direct chemical analysis for this species, male and female individuals were repeatedly scanned across key phases of the annual cycle, including hibernation, reproduction and transition phases between them. Body composition remained largely unchanged during prolonged dormancy, despite fasting and inactivity, with lean and mineral compartments comparatively maintained in both sexes. In contrast, reproduction was associated with the most pronounced seasonal shifts, including reductions in fat reserves and increases in protein- and water-related compartments in both sexes, together with mineral remodeling that was more evident in females. In subsequent months, several of these components shifted back toward pre-reproductive values. These patterns indicate a coordinated reorganization of energy and body resources across seasons, with fat reserves mobilized during reproduction while lean and mineral compartments followed distinct, phase-dependent trajectories. Our results suggest a partial decoupling between energy storage and structural maintenance, consistent with the idea that key functional compartments may be differentially buffered against seasonal constraints. By linking within-individual variation in energy reserves to shifts in physiological demands, this study provides an integrative physiological perspective on how life-history trade-offs are expressed in seasonal environments. More broadly, these findings contribute to understanding how physiological flexibility may influence organismal performance under changing environmental conditions. SUMMARY STATEMENT: Validated DEXA measurements revealed broad maintenance of lean and mineral compartments during dormancy in both sexes, followed by fat mobilization during reproduction and sex-specific mineral remodeling, particularly in females.
Plant extracts rich in bioactive compounds, particularly polyphenols, have gained increasing attention in poultry breeder nutrition owing to their antioxidant and anti-inflammatory properties. These properties help preserve intestinal integrity and support improvements in gamete quality and embryonic viability. Commercial feed products, such as Elife®, have been developed to incorporate additives, including flavonoids, proanthocyanidins, and phenolic acids, delivering polyphenols in highly bioavailable forms and ensuring effective antioxidant activity. This study evaluated the effects of dietary supplementation with Elife® in brown egg-layer breeders (males and females) on productive and reproductive performance, egg quality, incubation traits, and progeny outcomes. Two experiments were conducted with birds aged from 54 to 70 weeks. In Experiment 1, 30 Rhode Island Red roosters were allocated to the following treatment groups: basal diet without additives (CON); basal diet + 0.5 kg of Elife®/t of feed (E500); and basal diet + 1 kg of Elife®/t of feed (E1000). Body weight, feed intake, and sperm quality were measured in each rooster every 28 days. For Experiment 2, 210 White Plymouth Rock brown egg-layer hens were assigned to the same three treatments as in Experiment 1. Body weight, feed intake, laying rate, egg quality, and incubation parameters were recorded every 28 days. Roosters receiving E1000 showed significantly improved sperm motility and an increased proportion of morphologically normal sperm without affecting feed intake, body weight, or sperm vigor. Hens under E1000 had lower feed intake than controls while maintaining egg quality (P > 0.05). Furthermore, combined parental supplementation with Elife® improved egg hatchability, reduced early embryonic mortality, and increased day-old chick weight. Overall, combined parental supplementation with Elife® demonstrated an effective nutritional strategy for improving fertility, embryonic viability, and chick quality in brown egg-layer breeders.
Sea urchin grazing can drive kelp loss creating low productivity "barrens" with reduced biodiversity that may persist for decades. In these habitats, limited food driven by sea urchin herbivory reciprocally affects sea urchin physiology, yet the metabolic pathways enabling survival in the starvation conditions remain poorly understood. This study employed gas chromatography-mass spectrometry metabolomics to compare gonad metabolite profiles of purple sea urchins, Strongylocentrotus purpuratus, from barrens and adjacent kelp forest margins. Gonads from barren animals showed pronounced metabolic reallocations relative to kelp-margin animals, supporting energy production, redox balance, and membrane integrity. Carbohydrate metabolism was shifted towards increased glucose and gluconeogenesis with reduced alanine and glutamine as substrates for energy production. The pentose phosphate pathway fluxed towards energy production (supported by elevated sedoheptulose and mannoheptulose, and reduced glutamine and glutamate), rather than nucleotide synthesis and growth. Elevated amino acids (cysteine, cystine and lysine) reflected gonad protein catabolism, energy production and redox balance. Changes in lipid metabolism showed elevated monostearin from lipid breakdown, reduced heptanoic acid as energy substrate, and increased malonate supporting membrane integrity. This study reveals the specific metabolic adjustments purple sea urchins employ under food-limited conditions in barrens, diverting energy from reproduction to enhance long-term survival, potentially signaling challenges for kelp restoration.
What did our ancestors eat? Current understanding of diet in human evolution is predicated on abundant animal foods and mastery of fire, both unlikely for early hominins. Using multiple lines of evidence, including the metabolic requirements of an enlarging brain and reproduction, we model macronutrient distribution across 4 million years of evolution. Before cooking made starch easily digestible, the sugars in fruit and honey provided glucose, the brain's preferred fuel. Modeling suggests that sugars provided >25% of dietary energy, fulfilling obligatory glucose demand. Pounding and cooking released glucose specifically, not merely energy. The evolution of a bigger brain is therefore a story of carbohydrate foods as much as animal foods: from sweet sugars to cooked starch, from chewing to processing, and from wadging to advanced nutrient extraction.
Information about on-farm goat productivity patterns is crucial for building resilient production systems in marginalised communities. Goat flock dynamics, management practices and production constraints in selected smallholder farming systems of Zimbabwe were explored. A multistage sampling approach was adopted to recruit a total of 200 participants. The effect of environment on productive indices and constraints was analysed using the Mann-Whitney U test and either Ordinal or Nominal logistic regression, respectively, in IBM SPSS version 26. Results highlight the importance of goats to rural communities. On average, 10.01 ± 5.14 goats were maintained per capita and the largest proportion was found in hot-humid environments (p > 0.05). However, reproductive performance in terms of average gestation length (4. 47 ± 0.59 months), age at first service (11.20 ± 2.24 months) and kidding (15.67 ± 2.30 months) was poorer in semi-arid environments than in the hot-humid areas (p > 0.05). Moreover, optimum productivity is hampered by a multitude of factors, including selection of breeding animals mainly based on personal appraisal (Index = 0.120), dependence of animals primarily on natural forages for feed (Index = 0.213), sub-optimal housing conditions like irregular cleaning (Index = 0.123) and disease preponderance (Index = 0.129). Ailments were mainly controlled using ethnoveterinary medicines (Index = 0.103). Taken together, our results underline the crucial role of goats to rural livelihoods, which could be elevated even more through community-based capacity building on proper animal husbandry practices in terms of breeding, nutrition, health and housing management.
This paper is a narrative review focusing on the association between environmental cadmium exposure and male reproductive dysfunction. The relationship between environmental pollutants encountered in daily life and the male reproductive system is attracting increasing attention. Humans are exposed to cadmium through inhalation, dietary intake (food) and other routes, leading to adverse health effects. This study systematically searched PubMed, Web of Science, and CNKI databases from January 1, 2020, to December 31, 2024, and included 40 eligible in vivo studies based on standardized selection criteria. This study reviewed and analyzed relevant animal experiments conducted in recent years. Based on the lowest observable adverse effect level (LOAEL, 10 μg/kg/d) for reproductive toxicity in rats from a chronic 90-day study (Ait Benbella et al., 2025), the minimum critical human equivalent dose (HED) of cadmium-induced male reproductive damage was calculated, All 40 studies in Table 1 were selected according to predefined inclusion/exclusion criteria (see Section 2). The Lowest-Observed-Adverse-Effect Level (LOAEL) was converted to HED using the following formula: H E D ( m g / k g ) = A n i m a l   L O A E L   ( m g / k g ) × k m   o f   a n i m a l   k m   o f   h u m a n (The LOAEL was derived from rat reproductive toxicity data (10 μg/kg/d) (Ait Benbella et al., 2025); km factors of 6 (rat) and 37 (human, 60kg) were applied. The calculated HED was 0.002 mg/kg/d.) Comparisons reveal that cadmium exposure levels in some regions approach or even exceed this threshold. The results suggest that cadmium may cause damage to the male reproductive system, potentially adversely affecting semen quality. Cadmium also induces renal dysfunction that indirectly exacerbates testicular injury via the renal-testis axis, further disrupting the hypothalamic-pituitary-testicular axis and amplifying reproductive toxicity. These findings highlight the integrated renal-reproductive toxicity of environmental cadmium exposure.
Leptin, discovered in 1994 in ob/ob and db/db mutant mice, is a key regulator of energy balance, appetite, and multiple physiological systems including immunity and reproduction. While its function in mammals is well-established, leptin's presence and role in birds remain controversial due to differences in gene sequence, tissue expression, and signaling mechanisms. Avian leptin exhibits a GC-rich sequence, predominates in autocrine and paracrine signaling, and maintains conserved receptor-binding residues, supporting functional activity despite low systemic levels. Experimental studies show leptin influences feed intake, immune function, and reproduction, though conflicting results have fueled ongoing debate. In this review, we discuss evidence supporting and questioning avian leptin function and highlight emerging gene-editing approaches, including CRISPR/Cas9-mediated manipulation of leptin and its receptor in poultry, as powerful tools to clarify its functional dynamics in vivo, resolve longstanding uncertainties, and potentially enhance poultry growth and production efficiency.
Untreated manure is commonly used as a biological soil amendment of animal origin in organic production but may introduce foodborne pathogens into the farm environment. In this multi-regional study, generic E. coli was used as an indicator of fecal contamination to identify factors associated with its in manure-amended soils. The analysis included samples from 19 certified organic farms in California, Maine, Minnesota, and Maryland collected over two growing seasons. A zero-inflated linear mixed model was used to assess the association between generic E. coli concentration in soil, farm-related practices, soil and environmental factors. Generic E. coli concentration in the soil rapidly declined in the first 60 days after manure application (β: -1.00, CI95: -1.17, -0.83) before a secondary increase through Day 180. Manure management practices, including use of different types of animal manure and manure application rates, were significantly associated with generic E. coli in soil. Soil nutrients (phosphorus (β: 0.22, CI95: 0.15, 0.30)) and micronutrients (zinc (β: 0.03, CI95: 0.01, 0.04) and manganese (β: 0.02, CI95: 0.01, 0.02)), elevated moisture content (β: 0.13, CI95: 0.07, 0.19), and Salmonella (β: 1.79, CI95: 1.31,2.23) or Listeria monocytogenes (β: 0.24, CI95: 0.03, 0.44) also showed positive association with generic E. coli in soil. Lower wind speed (β: -0.12, CI95: -0.19, -0.06), increased precipitation (β: 0.03, CI95: 0.01, 0.05), and increased UV index (β: 0.24, CI95: 0.15, 0.34) were found to be associated with higher E. coli concentration in manured soil. Overall, the persistence of generic E. coli in manure-amended soil was multifactorial. Effective microbial risk management should incorporate considerations for origin of manure, management, environmental and meteorological factors alongside current USDA National Organic Program standards (90-120 days) regarding the interval of application of raw manure to harvest of the edible portion of food crops.
This study investigated the effects of letrozole (LE) on reproductive performance, hormones, and plasma metabolites in Turpan Black ewes. Sixty-six multiparous non-pregnant ewes were randomly assigned to a Control group or an LE group (0.2 mg/kg body weight, added to the basal diet) for 180 days, both receiving estrus synchronization. LE significantly increased the twinning rate (p < 0.05), but no significant differences were observed in estrus rate, conception rate, or lambing rate (p > 0.05). Hormone analysis revealed significant changes in Luteinizing Hormone (LH), Progesterone (P4) (group, time, and interaction effects), Estradiol (E2), Testosterone (T) (time effect), Gonadotropin-Releasing Hormone (GnRH) (group and interaction effects), and Follicle-Stimulating Hormone (FSH) (primarily time effect). Metabolomic analysis identified 3451 differential metabolites. L-saccharopine and 5-hydroxylysine were downregulated (p < 0.01), and estrone was decreased (p < 0.05). Lysylhistidine was upregulated (p < 0.05), while testosterone and LE showed rising trends without statistical significance (p > 0.05). These metabolites were mainly enriched in amino acid metabolism and lipid metabolism pathways related to reproduction. Significant correlations were also detected between several metabolites and reproductive hormones. LE improves the twinning rate in Turpan Black ewes, likely by modulating key reproductive hormones (LH, P4, GnRH, FSH, E2, T) and altering plasma metabolites involved in amino acid and lipid metabolism. These findings provide new insights into the regulatory mechanisms of letrozole on ovine reproduction.
Communication systems shape behavioral interactions that are crucial for recognition, territoriality, and reproduction across animals. In many anuran species, acoustic communication drives reproductive and defensive behaviors as males produce advertisement calls to establish territories and attract females. Understanding the temporal dynamics in vocalizations and their variation between and within males can provide crucial insight into the mechanisms that generate call patterning and communication. Here, we examine such dynamics in the call patterning of male Boana pulchella, a South American treefrog species that produces temporally-variant call series over time. Using rhythm analysis, we quantify the rhythmic structure of these vocalizations and characterize the variability in their temporal patterning between males. We find that rhythmic isochrony is timescale-dependent - call series are produced isochronously while the patterning of calls and notes within these series is non-isochronous yet periodic. The isochronous rhythm is maintained through an inverse relationship between series duration and the silence interval that follows it, such that longer series are followed by shorter silence intervals. Temporal features of calls and notes as well as their variation vary depending on within-series patterning dynamics and across timescales. Taken together, these results suggest that B. pulchella vocal timing is generated by hierarchically organized oscillators that produce isochronous vocalizations over a calling bout through flexible modulation at finer timescales.
Advanced methodologies for Botryllus schlosseri artificial seawater systems are needed to decrease dependency of large-scale culture on natural seawater and expand this important new model organism to more inland laboratories. We constructed two botryllid tunicate customized closed aquaculture systems, a static system consisting of aerated jars fed commercial filter feeder diet, and a recirculating aquaculture system (RAS) consisting of pertinent marine RAS components fed live microalgae and zooplankton diets. Initially, static tunicate culture yielded exponential growth in contrast to poor survival and negligible growth observed in RAS tunicates. RAS modifications were made to increase water treatment proficiency, which improved tunicate survival and growth. Experiments were performed isolating feed and water type as variables differentiating static and RAS and evaluating their specific effects. Live feed promoted five-fold greater growth relative to a commercial concentrate diet. Tunicates maintained in optimized RAS water achieved two-fold faster growth relative to animals in freshly prepared artificial seawater. Subsequent procedural modifications combined with the RAS revisions resulted in growth rates comparable to the static system. Both optimized systems are suitable for long-term husbandry of botryllid tunicate populations supporting both sexual and asexual modes of reproduction, with a current RAS residence time of over 24 months.
Duolang sheep is a meat-fat dual-purpose breed originating from Xinjiang, China, and the genetic basis of body size variation in this breed remains unclear. Whole-genome resequencing was performed on 224 Duolang sheep with complete records for six body size traits. After variant calling, imputation, and quality control, 19.65 million high-quality SNPs were retained. After linkage disequilibrium pruning, 2.1 million relatively independent SNPs were used for a mixed linear model GWAS in GEMMA. Tajima's D and integrated haplotype score analyses were performed in a kinship-filtered subset of 60 animals, and SheepGTEx data were used to characterize tissue expression patterns. The GWAS identified 24 significant SNPs for height, body length, chest girth, shoulder width, and hip width. Integration of GWAS intervals with selection-signal regions prioritized 31 candidate genes, including CA10, WDR45B, FADS2, LGALS12, and CTNNA2. Multi-tissue expression profiles provided functional context for the prioritized genes. These findings provide insight into the genetic architecture of body size traits in Duolang sheep and identify candidate loci for future validation and genetic improvement studies.
Early nutritional programming can affect later development in birds, yet the carryover effects of dietary arginine in Japanese quail remain poorly understood. Arginine is an essential amino acid for birds, as they cannot synthesise it endogenously, and it plays a vital role in growth and metabolism. This study aimed to evaluate the effect of dietary arginine restriction or supplementation on body mass change, reproduction, and plasma biochemistry in Japanese quail after the dietary treatment was discontinued for two consecutive weeks. Birds were fed either a low-arginine diet (25% below recommendations), a control diet (recommendations), or a high-arginine diet (25% above recommendations) at the early reproductive stage and adult stage and were then subsequently returned to a standard diet for two weeks. Overall, in comparison with the immediate effects of dietary arginine, no significant residual effects of dietary arginine were observed on body mass change, average daily body mass gain, feed conversion ratio, and egg production after the withdrawal period. However, age-dependent responses were observed, and adult birds showed a significant decrease in body mass change as compared to early reproductive stage birds. In addition, cholesterol showed age-related differences, whereas alanine aminotransferase (ALT/GPT) and aspartate aminotransferase (AST/GOT) showed both age- and treatment related difference with adult birds exhibiting lower concentrations than early-reproductive-stage birds. These findings suggest that early-life dietary arginine manipulation has a limited influence on growth and reproduction after withdrawal but may induce age-dependent changes in selected biochemical parameters in Japanese quail.
The Boer goat, a key global meat breed originating from South Africa, has been exported for breeding in over 70 countries, leading to diverse selection pressures and environmental adaptations. In this context, the main objectives of this study were to quantify genome-wide diversity, breed structure, and selection signatures in Boer goats from nine countries to identify shared and population-specific adaptation and production-related signals. Genomic information of 321 Boer goats from nine populations worldwide was analysed: Australia (AUS), Canada (CAN), New Zealand (NZL), South Africa (ZAF), Switzerland (CHE), Tanzania (TZA), Uganda (UGA), United States (USA), and Zimbabwe (ZWE). Genetic diversity varied markedly among populations. The ZAF population exhibited the lowest observed heterozygosity (0.360) and the highest fraction of the genome in runs of homozygosity, suggesting recent inbreeding or strong selection. Population structure analyses, including principal component analysis and ADMIXTURE (optimal K = 8), revealed clear genetic differentiation. AUS Boer goats were the most divergent, while others formed clusters indicating shared ancestry. Four complementary selection signature methods, Fixation index, Divergence index, integrated haplotype score, and cross-population extended haplotype homozygosity, identified 4 706 unique genes under putative selection. No identified genes were common to all populations, indicating strong local adaptation, but 35 candidate genes were identified across five to six populations, highlighting shared selection for core production traits like growth, metabolism, and reproduction. Key shared genes regulating metabolism, including PPP2R2B, SCP2, and PRELID2, were detected in six populations. Regulatory hub genes such as MAPK3, HIF1A, PRKACA, and CREB1 were also detected, playing crucial roles in coordinating important biological processes. Population-specific adaptations included heat tolerance genes in AUS, cold adaptation and reproductive performance genes in CAN, and disease resistance genes in ZAF. These results underscore the need to monitor local genetic diversity while improving production traits in Boer goat breeding worldwide.
Successful reproduction in eutherian mammals requires intimate connections between the embryo and uterus, involving adhesion, attachment and placentation, with or without invasion of the endometrium. The complex dialogue between embryo and uterus involves numerous molecules and pathways. The study of the mechanisms driving early embryo-uterus interactions has historically been challenging, particularly discovering the embryo-expressed molecules. Some components of the interactions have been known for decades, but many have been revealed in recent years through innovative transcriptome studies, studies of the contents and functions of extracellular particles, use of in vitro three-dimensional organoids, genetic studies, approaches for dissecting the regulation of maternal immune system cells, and many other approaches. This review focuses on embryo-expressed molecules that support implantation and embryo attachment, implantation and pregnancy establishment. Both classical and recent discoveries are examined, encompassing results from human, murine, livestock and comparative studies. Opportunities for further mechanistic insights are considered. Additionally, the review considers the potential for agricultural and clinical applications of the more recently identified molecular players and mechanisms for enhancing reproductive success or for providing new approaches to contraception.
The objective of this study was to estimate (co)variance components and genetic parameters for litter size at birth (LSB), litter size at weaning (LSW), and kid mortality from birth to weaning in Markhoz goats. Data were obtained from the Markhoz Goat Breeding Station in Sanandaj, Iran, and comprised 3439 records for LSB and LSW and 4087 records for kid mortality, collected over a 21-year period. Birth year and dam age had significant effects on LSB and LSW (P < 0.05), while birth year, dam age, birth type, and sex significantly affected kid mortality (P < 0.05). Genetic analyses for LSB and LSW were performed using linear and Poisson models, whereas linear and probit models were applied to mortality. Model performance was evaluated using predictive ability and goodness-of-fit statistics based on mean squared error of prediction and correlations between observed and fitted values. Heritability estimates ranged from 0.02 to 0.04 for LSB, 0.02 to 0.05 for LSW, and 0.16 to 0.35 for mortality. Estimated random effects, breeding values, and permanent environmental effects were highly correlated across models. For LSB, the linear model outperformed the Poisson model; for LSW, both models showed a similar fit, although the linear model had better predictive ability. For mortality, the linear model showed superior predictive performance, although the probit model uniquely identified maternal genetic and common litter effects. Overall, linear models are recommended for accurate animal ranking, whereas the probit model is preferred when the objective is to partition variance in binary traits into direct genetic, maternal, and litter components.
Reconstructing ancestral reproductive systems is crucial for understanding the evolution of bilaterian body plans. Yet, despite extensive research on some organ systems of the last common bilaterian ancestor, the evolution and development of reproductive systems remain poorly understood. To address this gap, we investigated postembryonic sexual development in the xenacoelomorph Hofstenia atroviridis, a basal acoel species belonging to the infraorder Prosopharyngida. We reared H. atroviridis from eggs to adults and described the ontogeny of its reproductive organs using histology and immunohistochemistry with muscle and neural markers, along with observations of mating behaviors in each size class. Hofstenia atroviridis is a protandrous simultaneous hermaphrodite whose sexual maturity correlates with body size rather than age, as observed in Hofstenia miamia. The male copulatory system comprises a seminal vesicle, granular vesicle, penis, and a single copulatory stylet, surrounded by regionally specialized musculature and innervation. In contrast, the female system consists of paired, asaccate ovaries with large, follicle cell-bound oocytes, lacking a discrete gonopore or copulatory organ. Fertilization occurs internally through traumatic insemination, and eggs are likely released through the mouth. Our findings reveal that the male reproductive system of H. atroviridis exhibits unexpected complexity and structural differentiation despite the organism's overall simplicity. We propose that sexual selection acting on a hermaphroditic reproductive system may have driven the evolution of a multifunctional copulatory organ in the Urbilateria. This study establishes H. atroviridis as a promising and comparative model for exploring the evolutionary origins of animal reproductive systems.
The growing global demand for ethical, resource-efficient protein sources has renewed serious interest in cultured meat as a viable alternative to conventional livestock production. Two revolutionary biotechnological systems, induced pluripotent stem cell (iPSC) reprogramming and CRISPR-Cas9-mediated genome editing, when combined, offer unparalleled accuracy and scalability for the biofabrication of avian flesh. In this review, we present a comprehensive pipeline that involves the ectopic expression of Yamanaka factors (Oct4, Sox2, Klf4, and c-Myc) to reprogram primary somatic cells derived from Gallus gallus into induced pluripotent stem cells (iPSCs). This process is subsequently followed by targeted genome editing to enhance myogenic potential, growth efficiency, nutritional composition, and disease resistance. iPSCs are cultivated in a xeno-free bioreactor following genome editing, and subsequently directed to develop into myoblasts and mature myotubes. Three-dimensional tissue biofabrication is realized by combining biomaterial scaffolds and perfusion bioreactor systems, structuring an authentic muscle tissue matrix. These engineering platforms enable precise control over microenvironmental parameters, including oxygenation and nutrient perfusion. The resulting biofabricated poultry product is compositionally optimized, free of antibiotic residues, and exhibits a significantly reduced environmental footprint than poultry that is grown in the traditional way. This all-in-one solution solves important problems in food security, animal welfare, land use efficiency, and greenhouse gas emissions while also setting up a scalable biomanufacturing framework for making proteins for the next generation.
We examined reproductive features of a pelvic brooder, the oviparous teleost Oryzias eversi. Eggs possess two types of filaments that form on the surface of the chorion during oogenesis: long attachment filaments at a restricted area around the vegetal pole, and sparse, short filaments around the animal pole (micropyle). Females spawned eggs through the genital pore when mating with the male. After spawning, females carried a cluster of fertilized eggs suspended from the genital pore by a bundle of long attachment filaments. Fertilized eggs were protected by the pair of long pelvic fins and held in an abdominal concavity posterior to those fins until hatching, about 12 days post-oviposition. During the period that females carried the fertilized egg cluster, the growth of oocytes slowed, and ovulation of a new batch of eggs did not occur. Thus, reproductive cycles in the female of O. eversi appear to depend upon the presence of hanging embryos.