Reproductive Longevity Research Articles

The mouse Balbiani body regulates primary oocyte quiescence via RNA storage

In mammalian females, the transition from dormancy in primordial follicles to follicular development is critical for maintaining ovarian function and reproductive longevity. In mice, the quiescent primary oocyte of the primordial follicle contains a Balbiani body (B-body), an organelle aggregate comprised of a spherical structure of Golgi complexes. Here we show that the structure of the B-body is maintained by microtubules and actin. The B-body stores mRNA-capping enzyme and 597 mRNAs associated with mRNA-decapping enzyme 1 A (DCP1A). Gene ontology analysis results indicate that proteins encoded by these mRNAs function in enzyme binding, cellular component organization and packing of telomere ends. Pharmacological depolymerization of microtubules or actin led to B-body disassociation and nascent protein synthesis around the dissociated B-bodies within three hours. An increased number of activated developing follicles were observed in ovaries with prolonged culture and the in vivo mouse model. Our results indicate that the mouse B-body is involved in the activation of dormant primordial follicles likely via translation of the B-body-associated RNAs in primary oocytes.

Strongly deleterious mutations influence reproductive output and longevity in an endangered population

Inbreeding depression has been documented in various fitness traits in a wide range of species and taxa, however, the mutational basis is not yet well understood. We investigate how putatively deleterious variation influences fitness and is shaped by individual ancestry by re-sequencing complete genomes of 37 individuals in a natural arctic fox (Vulpes lagopus) population subjected to both inbreeding depression and genetic rescue. We find that individuals with high proportion of homozygous loss of function genotypes (LoFs), which are predicted to exert a strong effect on fitness, generally have lower lifetime reproductive success and live shorter lives compared with individuals with lower proportion of LoFs. We also find that juvenile survival is negatively associated with the proportion of homozygous missense genotypes and positively associated with genome wide heterozygosity. Our results demonstrate that homozygosity of strongly and moderately deleterious mutations can be an important cause of trait specific inbreeding depression in wild populations, and mark an important step towards making more informed decisions using applied conservation genetics.

Systemic low-dose anti-fibrotic treatment attenuates ovarian aging in the mouse.

The female reproductive system is one of the first to age in humans, resulting in infertility and endocrine disruptions. The aging ovary assumes a fibro-inflammatory milieu which negatively impacts gamete quantity and quality as well as ovulation. Here, we tested whether the systemic delivery of anti-inflammatory (Etanercept) or anti-fibrotic (Pirfenidone) drugs attenuates ovarian aging in mice. We first evaluated the ability of these drugs to decrease the expression of fibro-inflammatory genes in primary ovarian stromal cellstreated with a pro-fibrotic or a pro-inflammatory stimulus. Whereas Etanercept did not block Tnf expression in ovarian stromal cells, Pirfenidone significantly reduced Col1a1 expression. We then tested Pirfenidone in vivo where the drug was delivered systemically via mini-osmotic pumps for 6weeks. Pirfenidone mitigated the age-dependent increase in ovarian fibrosis without impacting overall health parameters. Ovarian function was improved in Pirfenidone-treated mice as evidenced by increased follicle and corpora lutea number, AMH levels, and improved estrous cyclicity. Transcriptomic analysis revealed that Pirfenidone treatment resulted in an upregulation of reproductive function-related genes at 8.5months and a downregulation of inflammatory genes at 12months of age. These findings demonstrate that reducing the fibroinflammatory ovarian microenvironment improves ovarian function, thereby supporting modulating the ovarian environment as a therapeutic avenue to extend reproductive longevity.

Cesarian section and long-term outcomes for cownose rays (Rhinoptera bonasus).

Cownose rays (Rhinoptera bonasus) are schooling rays commonly displayed in large groups in public aquariums. They are long-lived, have an annual reproductive cycle, and readily breed in managed care with most pregnancies culminating with the unaided and successful birth of a single neonate. Occasionally, females are observed to have prolonged pregnancies or suffer dystocia during parturition and intervention via a cesarian section (C-section) is required to deliver the neonate. Monthly reproductive monitoring at Ripley's Aquarium of the Smokies using ultrasound to stage pregnancies allows for the prediction of anticipated due dates and guides the decision to assist with delivery. Recognizing when to assist birth and best practices for performing C-section are important for the reproductive health, sustainability, and longevity of this species in managed care. This report describes a surgical technique for C-section in cownose rays and includes short-term complications and long-term outcomes for females.

Reproductive consequences of the interaction Trypanosoma cruzi − Triatoma infestans and its trade-off with survival

Relative little is known about fitness effects and life history trade-off of Trypanosoma cruzi in Triatoma infestans, the main vector of Chagas disease in Argentina. Previous studies revealed some costs related to development, excretion, and toxicology or their possible trade-offs, but none address effects on reproduction. To study the effect of T. cruzi infection on reproductive efficiency and survival of T. infestans we set up four treatments: both genders uninfected, both genders infected, female infected – males uninfected and female uninfected − males infected. The infection was induced during the third, fourth, and fifth nymphal instars. Reproductive efficiency and longevity variables were recorded. Our results showed that the infection by T. cruzi increased reproductive efficiency and reduced survival of T. infestans. Pairs where one or both individuals were infected presented a greater percentage copulation, of egg-laying females, the onset of copulation and oviposition occurred earlier, and age-specific fecundity was notably higher. Regarding fertility, infected females displayed higher rates irrespective of the infective status of the male counterpart. A reduction in longevity was observed in infected males and females. These findings highlighted that the infection significantly alters the trade-off reproductive efficiency-survival of T. infestans, with the impact differing according to the infection status of each gender, suggesting a complex interplay rather than a simple additive effect. This response corresponds to the reproductive compensation hypothesis.

Boll weevils in dry bolls: is there a performance disadvantage?

BackgroundAnthonomus grandis grandis is the main cotton pest in the Americas, with the potential to become a pest in other continents. The insect uses the plant’s reproductive organs for feeding, oviposition, and survival strategies in the off-season, sheltering in dry bolls. This study aimed to know the reproductive potential, feeding, longevity, and morphometric characteristics of boll weevils from dry bolls, squares, and traps. Adults were obtained from infested squares, dry bolls, and traps installed in cotton fields and the Caatinga area. Thirty weevil pairs were maintained in the laboratory to assess the oviposition, feeding holes, longevity, and morphometric measurements of the parental and F1 generations.ResultsIn the parental generation, boll weevils from traps (the Caatinga area and cotton cultivation) showed greater reproductive potential. Boll weevils from squares and the Caatinga area showed greater feeding activity compared with those from cotton cultivation. Greater rostrum length, thorax + abdomen length, and abdomen width were observed in boll weevils from cotton cultivation and dry bolls. The origin of boll weevils parental generation did not affect progeny emergence time. The F1 generation of boll weevils showed significant differences in average longevity depending on the origin of different microhabitats. Furthermore, differences in rostrum lengths were observed, with the boll weevils coming from traps installed in cotton cultivation, the Caatinga area, and dry bolls being the largest. Regarding thorax + abdomen length and abdomen width, the highest values were observed in those from the Caatinga area and cotton cultivation.ConclusionIt was proven that dry bolls did not affect the reproductive, feeding, and longevity performance of boll weevils, enabling better insect fitness (reproduction and size) in relation to those coming from squares. The use of dry bolls as off-season shelter is an important survival strategy for the boll weevil.

P-350 Recombinant human anti-Müllerian hormone reduces doxorubicin-induced reproductive aging by regulating Id3 expression and promoting DNA repair

Abstract Study question What is the mechanism of ovarian damage after doxorubicin (Dox) treatment and how recombinant human anti-Müllerian hormone (rhAMH) suppresses ovarian aging and prevents chemotherapy-induced damage? Summary answer Administration of rhAMH attenuates Dox-induced follicle depletion and protects the ovarian reserve in mice, primarily by reducing DNA damage via Id3 upregulation. What is known already Treatment with rhAMH results in reversible ovarian quiescence that can reduce primordial follicle depletion induced by Dox when it is used as an adjuvant. However, the exact mechanism of Dox-induced ovarian toxicity and the mechanisms by which rhAMH rescue this damage were unknown. Study design, size, duration For the in vivo experiments: 25-day-old mice were randomized into four treatment groups (Control, Dox, Dox+rhAMH, and rhAMH) for three different timepoints (n = 5 per group, total n = 60). Ovaries were removed for analysis at 4, 24 hours and and 1 week after treatment. For the in vitro studies: 21-day-old mice (n = 30) were treated with subcutaneous injection of diethylstilbestrol (DES) to enhance preantral follicle growth, and primary granulosa cells were collected by mechanical dissociation. Participants/materials, setting, methods Immunohistochemistry with DDX4 and counter staining with hematoxylin was used for differential follicle counts. DNA damage and apoptosis were measured by quantification of phosphorylated form of histone 2AX (γH2AX) and by TUNEL assay. MTS assay, clonogenic assay and siRNA Id3 RNA interference knockdown experiment were carried out to reveal the effects of doxorubicin and rhAMH on primary granulosa cell survival. Main results and the role of chance Treatment with Dox alone caused significant loss of PMF reserve (59% reduction, 5.25 versus 12.76 in control, P<0.0001) and this was significantly attenuated by coadministration with rhAMH (33% rescue, 9.47 P<0.001). The DNA damage marker γH2AX was elevated in primordial follicle (PMF) and primary follicle (PF) oocytes from Dox-treated ovaries 4 h after treatment, compared with controls (P<0.0001) and was significantly reduced (95% reduction) in rhAMH cotreated ovaries (P<0.001). Oocytes of secondary follicle (SF) and antral follicle (AF) were negative for γH2AX while granulosa cells (GCs) showed increased positivity for γH2AX after Dox treatment with significant reduction after rhAMH cotreatment. (24% reduction, P<0.001). Oocytes and somatic cells of PMF and PF rarely showed positive TUNEL staining at any of the timepoints evaluated.In vitro study showed reduced double stranded breaks (DSBs) in Dox-rhAMH cotreated GC compared to Dox alone indicated by number and signal intensity of γH2AX positive cells. Finally, while rhAMH treatment increased Id3 expression in early stage oocyte and granulosa cells, siRNA Id3 knock-down in granulosa cells significantly reduced the protective effect of rhAMH, as seen by the increased DSBs and pyknotic morphology of cells after Dox suggesting Id3 is downstream of AMH and enhancing Dox-induced DSB DNA repair. Limitations, reasons for caution This study failed to detect fate of PMF after DNA damage. PMF distinguished without apoptotic finding and this might be because experiment was conducted in limited time point or mechanism other than apoptotic cell death are responsible for PMF loss such as shedding, phagocytosis or necrosis. Wider implications of the findings Understanding of the mechanism behind rhAMH prevention of chemotherapy-induced reproductive aging is important for reproductive health and longevity. Possibility of rhAMH as non-invasive ferto-protective agent during chemotherapy may overcome limitation of current fertility preservation method which is limited by time requirement, cost and success rate. Trial registration number ’not applicable’

Systemic low-dose anti-fibrotic treatment attenuates ovarian aging in the mouse.

The female reproductive system is one of the first to age in humans, resulting in infertility and endocrine disruptions. The aging ovary assumes a fibro-inflammatory milieu which negatively impacts gamete quantity and quality as well as ovulation. Here we tested whether the systemic delivery of anti-inflammatory (Etanercept) or anti-fibrotic (Pirfenidone) drugs attenuates ovarian aging in mice. We first evaluated the ability of these drugs to decrease the expression of fibro-inflammatory genes in primary ovarian stromal cells. Whereas Etanercept did not block Tnf expression in ovarian stromal cells, Pirfenidone significantly reduced Col1a1 expression. We then tested Pirfenidone in vivo where the drug was delivered systemically via mini-osmotic pumps for 6-weeks. Pirfenidone mitigated the age-dependent increase in ovarian fibrosis without impacting overall health parameters. Ovarian function was improved in Pirfenidone-treated mice as evidenced by increased follicle and corpora lutea number, AMH levels, and improved estrous cyclicity. Transcriptomic analysis revealed that Pirfenidone treatment resulted in an upregulation of reproductive function-related genes at 8.5 months and a downregulation of inflammatory genes at 12 months of age. These findings demonstrate that reducing the fibroinflammatory ovarian microenvironment improves ovarian function, thereby supporting modulating the ovarian environment as a therapeutic avenue to extend reproductive longevity.

Metabolome-wide Mendelian randomization for age at menarche and age at natural menopause.

The role of metabolism in the variation of age at menarche (AAM) and age at natural menopause (ANM) in the female population is not entirely known. We aimed to investigate the causal role of circulating metabolites in AAM and ANM using Mendelian randomization (MR). We combined MR with genetic colocalization to investigate potential causal associations between 658 metabolites and AAM and between 684 metabolites and ANM. We extracted genetic instruments for our exposures from four genome-wide association studies (GWAS) on circulating metabolites and queried the effects of these variants on the outcomes in two large GWAS from the ReproGen consortium. Additionally, we assessed the mediating role of the body mass index (BMI) in these associations, identified metabolic pathways implicated in AAM and ANM, and sought validation for selected metabolites in the Avon Longitudinal Study of Parents and Children (ALSPAC). Our analysis identified 10 candidate metabolites for AAM, but none of them colocalized with AAM. For ANM, 76 metabolites were prioritized (FDR-adjusted MR P-value ≤ 0.05), with 17 colocalizing, primarily in the glycerophosphocholines class, including the omega-3 fatty acid and phosphatidylcholine (PC) categories. Pathway analyses and validation in ALSPAC mothers also highlighted the role of omega and polyunsaturated fatty acids levels in delaying age at menopause. Our study suggests that metabolites from the glycerophosphocholine and fatty acid families play a causal role in the timing of both menarche and menopause. This underscores the significance of specific metabolic pathways in the biology of female reproductive longevity.

Functional role of autophagy in testicular and ovarian steroidogenesis.

Autophagy is an evolutionarily conserved cellular recycling process that maintains cellular homeostasis. Despite extensive research in endocrine contexts, the role of autophagy in ovarian and testicular steroidogenesis remains elusive. The significant role of autophagy in testosterone production suggests potential treatments for conditions like oligospermia and azoospermia. Further, influence of autophagy in folliculogenesis, ovulation, and luteal development emphasizes its importance for improved fertility and reproductive health. Thus, investigating autophagy in gonadal cells is clinically significant. Understanding these processes could transform treatments for endocrine disorders, enhancing reproductive health and longevity. Herein, we provide the functional role of autophagy in testicular and ovarian steroidogenesis to date, highlighting its modulation in testicular steroidogenesis and its impact on hormone synthesis, follicle development, and fertility therapies.

284 Relationship between sow caliper measurements with sow reproductive performance and longevity in the herd

Abstract Ideal conditioned sows are desired because they maximize herd performance, improve female well-being, and optimize financial outcomes. Sow productivity has increased, and body composition of females has changed, with sows being leaner and having less adipose tissue compared with their predecessors. Our objective was to determine the relationship between sow caliper measurements with sow reproductive performance and longevity in the herd. Data collected in four different production systems located in the US and Brazil were used, with 3,083, 356, 7,456, and 26,773 individual PIC Camborough observations represented within each of these databases. Caliper measurements were collected at due to farrow and weaned sows and were recorded in units, standardized to an ideal range of 12 to 15 units. Caliper change in lactation was determined as the caliper units at weaning minus the caliper units pre-farrowing. Response variables included proportion of born alive and stillborn piglets, lactation feed intake, as well as removal and mortality risk for all causes, or specifically for reproductive and pelvic organ prolapse (POP) causes. Data were analyzed using generalized linear mixed models, hazard ratio analysis, and survival models with the lmer, glmer, and surv functions of R. Sow served as the experimental unit. Caliper measurements at farrowing had curvilinear associations (P < 0.05) with percentage born alive piglets and percentage stillborn piglets. Increasing caliper units at farrowing resulted in linear reduction (P < 0.05) in lactation average daily feed intake and in linear increase (P < 0.05) in caliper losses during lactation. Sows losing 1 to 2, 3 to 4, or 5 and greater caliper units in lactation had 1.5, 1.8, and 2.4 times, respectively, greater risk (P < 0.05) of being removed from the herd in the next cycle compared with sows that gained 0 or more units. Reduced caliper units in due-to-farrow sows resulted in reduced probability (P < 0.05) of survival in the next cycle considering prolapse removal reasons. Sows with due to farrow caliper units of 12 to 15 had 1 to 1.6 times (95% Odd Ratio Confidence Interval), 9 to 11 had 1.2 to 2.1 times, and less than 9 caliper units 3.1 to 3.2 times greater risk of death or being removed from the herd due to POP compared with those with >15 units. Reduced caliper units in due-to-farrow sows resulted in reduced probability of survival in the next cycle considering all removal and mortality causes. Specifically, sows with less than 9 caliper units at farrowing had 2.0 times greater risk (P < 0.05) of removal and 4.4 times greater risk (P < 0.05) of mortality compared with sows with over 15 caliper units. In summary, both under and over-conditioned sows have reduced productivity. Underconditioned sows are at greater risk for mortality and for POP related removal.

42 Group sow housing considerations for improved survival and productivity

Abstract Group sow housing considerations for improved survival and productivity. The Australian pork industry decided in 2010 to voluntarily phase out stall housing for pregnant sows by 2017. The change was supported by extensive R&D by the Pork CRC for High Integrity Australian Pork and the time line was brought forward by two major retailers in Australia. For 85 to 90% of producers the transition was complete by 2019-2020 and sows were grouped at weaning or straight after mating. I reviewed the pertinent literature, interviewed many producers on what is required to make group housing successful for the sow and the producer and looked at trend from an Australian bench making project in some aspects of reproduction and sow mortality from 2006 to 2020. The research showed sows adapt to grouping and exhibit reduced aggressive behaviors, injuries and plasma indicators of stress within 4 to 5 d after mixing. During this period, it was all about space at mixing, grouping sows based on size/parity, ensuring they all receive adequate feed and familiarization with group housing by the sow and staff. Producers said it is all about ensuring sows are grouped on size/parity, feeding with many using ad libitum feeding for the week after mixing, space with a preference between 1.8 and 2.2 m2, flooring (slats preferred) and minimizing mixing events. Producers were split on the use of drop feeding and electronic sow feeders with opinions very divided. For drop feeding the preferred housing system comprised full length feeding stalls without a back gate. All producers said they would not go back to stalls. Most producers experienced a decline in farrowing rate and increased lameness during the transition. However, reproduction improved over time and sow mortality decreased. If the top 4 to 5 factors affecting aggressiveness and overall welfare are followed, group housing sows improves their welfare and does not reduce their reproductive performance or longevity. Detection of estrus can be more difficult in groups and a number of Australian producers have implemented the use of satiety blocks during the first 2 and last 2 wk of gestation to further improve welfare and meet retailer requirements. Mating in groups (not stalls) has also been reported to improve reproduction.

Life history correlations and trade-offs resulting from selection for dispersal in Tribolium castaneum.

Dispersal is an important facet of the life history of many organisms and is, therefore, subject to selective pressure but does not evolve in isolation. Across nature, there are examples of dispersal syndromes and life history strategies in which suites of traits coevolve and covary with dispersal in combinations that serve to maximize fitness in a given ecological context. The red rust flour beetle, Tribolium castaneum, is a model organism and globally significant post-harvest pest that relies on dispersal to reach new patches of ephemeral habitat. Dispersal behaviour in Tribolium has a strong genetic basis. However, a robust understanding of the relationship between dispersal and other life-history components, which could elucidate evolutionary processes and allow pest managers to control their spread and reduce the impact of infestation, is currently lacking. Here, we use highly replicated lines of T. castaneum previously artificially selected for divergent small-scale dispersal propensity to robustly test several important life history components: reproductive strategy, development time, and longevity. As predicted, we find that a suite of important changes as a result of our selection on dispersal: high dispersal propensity is associated with a lower number of longer mating attempts by males, lower investment in early life reproduction by females, slower development of later-laid offspring, and longer female life span. These findings indicate that correlated intraspecific variation in dispersal and related traits may represent alternative life history strategies in T. castaneum. We therefore suggest that pest management efforts to mitigate the species' agro-economic impact should consider the eco-evolutionary dynamics within multiple life histories. The benefits of doing so could be felt both through improved targeting of efforts to reduce spread and also in forecasting how the selection pressures applied through pest management are likely to affect pest evolution.

Shear wave elastography to assess stiffness of the human ovary and other reproductive tissues across the reproductive lifespan in health and disease†.

The ovary is one of the first organs to show overt signs of aging in the human body, and ovarian aging is associated with a loss of gamete quality and quantity. The age-dependent decline in ovarian function contributes to infertility and an altered endocrine milieu, which has ramifications for overall health. The aging ovarian microenvironment becomes fibro-inflammatory and stiff with age, and this has implications for ovarian physiology and pathology, including follicle growth, gamete quality, ovulation dynamics, and ovarian cancer. Thus, developing a non-invasive tool to measure and monitor the stiffness of the human ovary would represent a major advance for female reproductive health and longevity. Shear wave elastography is a quantitative ultrasound imaging method for evaluation of soft tissue stiffness. Shear wave elastography has been used clinically in assessment of liver fibrosis and characterization of tendinopathies and various neoplasms in thyroid, breast, prostate, and lymph nodes as a non-invasive diagnostic and prognostic tool. In this study, we review the underlying principles of shear wave elastography and its current clinical uses outside the reproductive tract as well as its successful application of shear wave elastography to reproductive tissues, including the uterus and cervix. We also describe an emerging use of this technology in evaluation of human ovarian stiffness via transvaginal ultrasound. Establishing ovarian stiffness as a clinical biomarker of ovarian aging may have implications for predicting the ovarian reserve and outcomes of Assisted Reproductive Technologies as well as for the assessment of the efficacy of emerging therapeutics to extend reproductive longevity. This parameter may also have broad relevance in other conditions where ovarian stiffness and fibrosis may be implicated, such as polycystic ovarian syndrome, late off target effects of chemotherapy and radiation, premature ovarian insufficiency, conditions of differences of sexual development, and ovarian cancer. Summary sentence: Shear Wave Elastography is a non-invasive technique to study human tissue stiffness, and here we review its clinical applications and implications for reproductive health and disease.

Reproductive Ageing: Unlocking the secrets of reproductive longevity: the potential of social insects.

Social insect queens display both extraordinary longevity and fertility. In this point of view, we describe their distinctive traits that make them useful models for reproductive longevity, holding implications for human health discoveries. Social insects present an extraordinary opportunity as models for reproductive longevity because they challenge the conventional patterns of aging and reproduction seen in other model organisms. Their queens are simultaneously long-lived and highly fecund, and understanding how these traits co-occur may lead to discoveries with important implications for human health.

Developmental programming of the ovarian reserve in livestock

Mammalian females are born with a finite number of follicles in their ovaries that is referred to as the ovarian reserve. There is a large amount of variation between females in the number of antral follicles that they are born with, but this number is positively correlated to size of the ovarian reserve, has a strong repeatability within a female, and a moderate heritability. Although the heritability is moderate, numerous external factors including health, nutrition, ambient temperature, and litter size influence the size and function of the ovarian reserve throughout life. Depletion of the ovarian reserve contributes to reproductive senescence, and genetic and epigenetic factors can lead to a more rapid decline in follicle numbers in some females than others. The relationship of the size of the ovarian reserve to development of the reproductive tract and fertility is generally positive, although some studies report antagonistic associations of these traits. It seems likely that management decisions and environmental factors that result in epigenetic modifications to the genome throughout life may cause variability in the function of ovarian genes that influence fecundity and fertility, leading to differences in reproductive longevity among females born with ovarian reserves of similar size. This review summarizes our current understanding of factors influencing size of the ovarian reserve in cattle, sheep, and pigs and the relationship of the ovarian reserve to reproductive tract development and fertility. It provides strategies to apply this knowledge to improve diagnostics for better assessment of fertility and reproductive longevity in female livestock.

Effects of reactive oxygen species and mitochondrial dysfunction on reproductive aging.

Mitochondria, the versatile organelles crucial for cellular and organismal viability, play a pivotal role in meeting the energy requirements of cells through the respiratory chain located in the inner mitochondrial membrane, concomitant with the generation of reactive oxygen species (ROS). A wealth of evidence derived from contemporary investigations on reproductive longevity strongly indicates that the aberrant elevation of ROS level constitutes a fundamental factor in hastening the aging process of reproductive systems which are responsible for transmission of DNA to future generations. Constant changes in redox status, with a pro-oxidant shift mainly through the mitochondrial generation of ROS, are linked to the modulation of physiological and pathological pathways in gametes and reproductive tissues. Furthermore, the quantity and quality of mitochondria essential to capacitation and fertilization are increasingly associated with reproductive aging. The article aims to provide current understanding of the contributions of ROS derived from mitochondrial respiration to the process of reproductive aging. Moreover, understanding the impact of mitochondrial dysfunction on both female and male fertility is conducive to finding therapeutic strategies to slow, prevent or reverse the process of gamete aging, and thereby increase reproductive longevity.

Single nucleotide polymorphism (SNP) marker-assisted breeding of Heterorhabditis bacteriophora for improvement of reproductive potential and stress tolerance

Summary The entomopathogenic nematode (EPN), Heterorhabditis bacteriophora, is an efficient biological control agent against several economically important insect pests. Recent research has assessed the possibility to correlate desired beneficial traits with genotype data to pave a way for marker-assisted breeding approaches. A collection of H. bacteriophora WT inbred lines has been phenotyped in this framework for stress- and virulence-related traits. However, these traits are rarely combined in a single line. Thus, unifying these traits in commercial strains is of high priority. This investigation unified beneficial traits in hybrid pools through marker-assisted breeding using single nucleotide polymorphisms (SNPs) associated with reproductive potential, longevity, virulence and cold tolerance. Recombinant inbred lines (RILs) generated from a cross between a stress tolerant WT inbred line (XX21) and a line high in in vitro reproduction potential (IL3) were genotyped via SeqSNP and screened for SNP markers associated with beneficial traits. Thereafter, a genotypic pool (X21L3) comprising 22 ILs was formed. The X21L3 pool was subsequently evaluated for the target traits in comparison with the cross parents and a commercial strain HB4. An improvement of oxidative stress tolerance at 2°C (cold tolerance) was recorded with X21L3 surviving 1 day longer than the best performing parent (XX21). The hybrid pool also survived 1 day longer than the least performing parent IL3 for the trait longevity at 25°C under oxidative stress conditions. A higher dauer juvenile (DJ) recovery (58%) and DJ yield (209 000 DJ ml−1) than the least performing parent XX21 was recorded for the pool. The storage stability in diatomaceous earth formulation at 2°C and 7.5°C was also improved by 2 and 5 days, respectively, in comparison to the least performing parent XX21. This study depicts the potential of precision marker-assisted breeding for beneficial trait improvement of H. bacteriophora.

Effect of Zucchini Yellow Mosaic Virus on the fecundity and longevity of vector, the Aphid Aphis gossypii, in Souk Ahras (East Algeria)

Zucchini Yellow Mosaic Virus (ZYMV) is one of the most important viral diseases of cucurbits in (East Algeria) and the world and it can be vectored by Aphids. Cotton (melon) Aphid, Aphis gossypii, is one of the most common insects in the Souk Ahras of (East Algeria) that can efficiently transmit ZYMV from infected to healthy cucurbit plants. The results of this study indicate that the vector insect, Aphis gossypii had significantly higher fecundity and longevity on zucchini plants infected with ZYMV compared with healthy plants. The massive reproduction and longer longevity of the vectoring (transmitting) insect (A. gossypii) on ZYMV infected plants can exacerbate the losses caused by both the insect pest (Aphids) and the viral disease agent (ZYMV) to zucchini and other cucurbit plants. The control of Aphids (the vector) is extremely important and can minimize the losses caused by both plant pests and can also reduce both primary (between fields) and secondary (within field) transmission of ZYMV.

Reproductive Longevity of the Russian Black Pied Cattle Depending on Period Length between Calving

The article deals with the indicators of reproductive longevity of the Russian black pied cattle depending on the period length between calving. The research object is the data of the electronic database of OAO “Zarya” of the Vologda Oblast. We divided animals of the study sample into four groups depending on the duration of the calving interval. We have studied indicators of productive longevity and reproductive qualities of cows. We have calculated underproduction with an increase in the duration of the calving interval. The highest number of completed lactations (3.4) and a fairly high lifetime milk yield of 25.6 kg are established in group II (calving interval is 366–425 days). This animal group has the highest milk productivity per day of life (10.5 kg), as well as a higher number of live calves (4.26 heads). Lower indicators of lifetime productivity, calf yield and reproductive qualities are obtained in group I (up to 365 days).