Female Egg Research Articles

Sublethal effects of emamectin benzoate on biological characteristics and the expression of vitellogenin (SgVg) and its receptor in Sclerodermusguani

Emamectin benzoate (EMB) is a commonly used insecticide for controlling agricultural and forest pests. To facilitate its rational use in integrated pest management (IPM), the sublethal effects of EMB on the development and reproduction of Scleroderma guani were evaluated. Sublethal doses of EMB (LD10 and LD30) significantly reduced the longevity and fecundity of F0 females. In the F1 generation, sublethal doses significantly reduced larval development duration and male longevity but significantly extended female longevity. Additionally, the LD30 treatment significantly decreased the number of laid eggs in F1 females by 20.72% compared with the control group. The net reproductive rate (R0) was significantly declined by the LD30 treatment compared with the control group (CK). Furthermore, the mean generation time (T) was significantly extended in both LD10 and LD30 treatment groups. Compared to the control group, the expression of SgVg and SgVgR genes in the LD10 and LD30 groups was significantly lower, which may be a crucial factor for the reduced fecundity of the females. These results indicate that sublethal doses of EMB significantly reduced adult longevity and fecundity of S. guani. The findings are practical for developing IPM strategies for forestry pests using S. guani and EMB.

A two-year plant-based diet alters the fatty acid profile and enzymatic and non-enzymatic lipid metabolites, in the eggs and fry of female rainbow trout

To promote sustainable aquaculture, plant-based ingredients are increasingly being used to replace fish meal (FM) and fish oil (FO) in diets, affecting critical fatty acid (FA) profiles in broodstock diets. These profiles are essential for reproduction and offspring survival. The absence of traditional fish-derived nutrients results in an altered FA composition, particularly a reduction in omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs). This change is detrimental to trout reproduction over the long term. Current research gaps, especially regarding FA profiles and related metabolites, limit our understanding of the reproductive consequences of omega-3 deficient plant-based diets. To fill this knowledge gap, a two-year trial was conducted to compare the reproductive effects (spawning performances, egg quality, embryo development) of two diets on rainbow trout females: a plant-based diet containing linseed (10.8 %), palm (5 %), and sunflower oils (2.7 %), and a commercial diet with high FM (27 %) and FO (12.1 %) content. Both diets were similar in terms of protein (44 %), lipids (23.4 %), and energy (25 kJ/g). The study spanned from initial feeding to first reproduction, and fatty acid profiles and metabolites (selected enzymatic and non enzyamatic metabolites from FA) were examined in the broodstock diet, female muscle tissue, eggs, and fry. Trout fed a plant-based diet showed reduced reproductive traits such as lower weight and fecundity, but egg and embryo quality remained high. Survival and hatching rates were similar to those on commercial diets. The study revealed for the first time the critical role of maternal diet in the generation of lipid metabolites in the offspring, particularly DHA (F4-neuroprostane, maresin, 14-HDoHE) and AA (F2-isoprostane, prostaglandin E and F2, 8–12- 15-HETEs) oxylipins, highlightingthe complex dietary influences on fish reproduction. This work underlines that a plant-based diet significantly affects the the reproductive performance of broodstock trout by altering fatty acid profiles and metabolite levels and highlights the delicate balance between dietary components, oxylipins, and reproductive functions in fish, suggesting the need for more comprehensive studies of their interrelated effects.

Premeiotic endoreplication is the mechanism of obligate parthenogenesis in rock lizards of the genus Darevskia.

Among vertebrates, obligate parthenogenesis occurs exclusively in squamate reptiles. Premeiotic endoreplication in a small subset of developing oocytes has been documented as the mechanism of production of unreduced eggs in minutely explored obligate parthenogenetic lineages, namely in teiids and geckos. The situation in the lacertid genus Darevskia has been discussed for decades. Certain observations suggested that the ploidy level is restored during egg formation through a fusion of egg and polar body nuclei in Darevskia unisexualis and D. armeniaca. In this study, we re-evaluated the fusion hypothesis by studying diplotene chromosomes in adult females of sexual species D. raddei nairensis and obligate parthenogens D. armeniaca, D. dahli and D. unisexualis. We revealed 19 bivalents in the sexual species and 38 bivalents in the diploid obligate parthenogens, which uncovers premeiotic endoreplication as the mechanism of the production of non-reduced eggs in parthenogenetic females. The earlier contradicting reports can likely be attributed to the difficulty in identifying mispairing of chromosomes in pachytene, and the fact that in parthenogenetic reptiles relying on premeiotic endoreplication only a small subset of developing oocytes undergo genome doubling and overcome the pachytene checkpoint. This study highlights co-option of premeiotic endoreplication for escape from sexual reproduction in all independent hybrid origins of obligate parthenogenesis in vertebrates studied to date.

Male-derived phospholipase A2 enhances WD46 expression and increases fertility in Ophraella communa.

Successful bisexual reproduction requires interactions between males and females. Male-derived seminal fluid proteins (SFPs) transferred to females during mating profoundly affect females from pre- to post-mating, and the subsequent shift in female physiology enhances their fertility. SFPs have important evolutionary implications for the fitness of many insects. However, little is known about how females respond to male SFPs. In this study, we identified a male-derived SFP-phospholipase A2 (PLA2) in Ophraella communa. PLA2 is a vital enzyme in eicosanoid biosynthesis; however, it has not been identified as an insect SFP. We found that OcPLA2 is specifically expressed in males, especially in the male accessory glands (MAGs); it is transferred to the female during mating and functions as an SFP to enhance fertility. The expression of a female-derived gene encoding the WD repeat-containing protein 46 (WD46) was upregulated when OcPLA2 entered the female reproductive tract, and this contributed to female egg production by increasing triacylglycerol lipase (TGL) gene expression and the triglyceride (TG) content. This is the first study to identify PLA2 as an SFP in insects. Our findings also shed light on the regulatory role of OcPLA2 in beetle reproduction; the expression of OcPLA2 is initially correlated with female WD46 expression and later with the decline in TGL gene expression and the TG content. This represents a unique mechanism of reproductive regulation by an SFP.

CRISPR/Cas9-mediated Nap knockout affects female reproduction and egg shape in Bombyx mori.

Insect reproductive capacity can affect effective pest control and infertility studies and has become an important focus in recent molecular genetic research. Nucleosome assembly protein (Nap) is highly conserved across multiple species and is involved in forming the sperm nucleus in many species. We used clustered regularly interspaced palindromic repeats/Cas9 technology to knockout BmNap in Bombyx mori and observed that the mutations caused female infertility, whereas male fertility was not affected. BmNap mutants grew and mated normally; however, female mutants laid smaller eggs that could not be fertilised and did not hatch. In addition, female sterility produced by the mutation could be inherited stably via male mutants; therefore, Nap could be used as a potential target for lepidopteran pest control through population regulation. In the current study, we elucidated a new function of BmNap, increased the understanding of the oogenesis regulation network in Lepidoptera and promoted the development of insect sterility technologies.

ADULT LONGEVITY OF Idea blanchardii (LEPIDOPTERA: NYMPHALIDAE) CAPTIVE BRED AT LIPI BUTTERFLY BREEDING FACILITY, CIBINONG, INDONESIA

Idea blanchardii is one of many endemic butterfly species in Sulawesi, Indonesia. This species is among the highly traded butterfly species thus requires biological information on the captive breeding. The aim of this study was to obtain data on the adult life-span, to report the multivoltine generation, and to provide conservation-related insight. Captive breeding research on this species was conducted within the period of September 2018 until February 2020. The host plant, Parsonsia alboflavescens, was used to support the life of this species for ovipositing and larval food plant. The adults would visit almost any flowers available at the facility. In total, 696 individuals were observed. Data on mating information of the species is presented here. Observations on when a female lays eggs are also revealed. This research showed that I. blanchardii is polygamous and polyandrous. Individuals of this species could live much longer than other butterfly species. A few could live over 80 days and one still seen laying eggs at the age of 136 days old.

Conditional Inhibition of Eip75B Eliminates the Effects of Mating and Mifepristone on Lifespan in Female Drosophila.

Mating in female Drosophila melanogaster causes midgut hypertrophy and reduced lifespan, and these effects are blocked by the drug mifepristone. Eip75B is a transcription factor previously reported to have pleiotropic effects on Drosophila lifespan. Because Eip75B null mutations are lethal, conditional systems and/or partial knock-down are needed to study Eip75B effects in adults. Previous studies showed that Eip75B is required for adult midgut cell proliferation in response to mating. To test the possible role of Eip75B in mediating the lifespan effects of mating and mifepristone, a tripartite FLP-recombinase-based conditional system was employed that provides controls for genetic background. Expression of a Hsp70-FLP transgene was induced in third instar larvae by a brief heat pulse. The FLP recombinase catalyzed the recombination and activation of an Actin5C-GAL4 transgene. The GAL4 transcription factor in turn activated expression of a UAS-Eip75B-RNAi transgene. Inhibition of Eip75B activity was confirmed by loss of midgut hypertrophy upon mating, and the lifespan effects of both mating and mifepristone were eliminated. In addition, the negative effects of mifepristone on egg production were eliminated. The data indicate that Eip75B mediates the effects of mating and mifepristone on female midgut hypertrophy, egg production, and lifespan.

Sublethal and transgenerational effects of broflanilide on the citrus red mite, Panonychus citri.

The citrus red mite, Panonychus citri is a serious pest of the citrus industry and has developed resistance to many acaricides. Broflanilide is a novel meta-diamide insecticide that binds to a new site on the γ -aminobutyric acid receptor with high potency against pests. However, little information has been reported about its effect on the citrus red mite. Broflanilide exhibited higher toxicity to female adults and eggs of a laboratory strain of P. citri The median lethal concentration (LC50), 9.769 mg/L and 4.576 mg/L, respectively) than other commonly used acaricides and was also toxic to two P. citri field strains. Broflanilide treatment with LC10, LC20, and LC30 significantly decreased the fecundity and longevity of female adults of F0 P. citri compared with the control. The duration of larva, protonymph, deutonymph and adult, and total life span in the F1 generation were significantly reduced after treatment of F0 with broflanilide. Population parameters, including the intrinsic rate of increase (r) and finite rate of increase (λ), were significantly increased, and the mean generation time (T) of F1 progeny was significantly reduced in the LC20 treatment. The predicted population size of F1 increased when parental female adults were treated with sublethal concentrations. Broflanilide had high acaricidal activity toward P. citri, and exposure to a sublethal concentration significantly inhibited the population growth of F0. The transgenerational hormesis effect is likely to cause population expansion of F1. More attention should be paid when broflanilide is applied to control P. citri in citrus orchards. © 2024 Society of Chemical Industry.

Spawning history, fecundity, and potential sperm limitation of female blue crabs in Chesapeake Bay

The blue crab (Callinectes sapidus) is an ecologically and economically important species in estuaries of the Western Atlantic Ocean and Gulf of Mexico. Given the importance of reproductive output and spawner demography on population dynamics, blue crab management may be improved if individual-based changes in egg production are identified and incorporated into management advice. We determined the spawning history, batch fecundity, and stored sperm quantity of 126 ovigerous blue crabs in 2022 to estimate the reproductive potential of female blue crabs in Chesapeake Bay. Our mean estimate of fecundity, 2.17 million eggs/female, is similar to a fecundity estimate from 1986 (2.6 million eggs/female), but lower than an estimate from 1987 (4.0 million eggs/female). The 1987 estimate was likely biased high due to methodological differences. In 2022, size-specific fecundity did not differ from that in 1986. Size-specific fecundity was lower by 0.28 million eggs in multiparous females (i.e., those that produced at least one previous egg mass) compared with primiparous females (i.e., those producing their first egg mass). Size-specific fecundity was also greater in July and August than in June, however, females in June had a greater capacity for future reproductive potential because their average stored sperm quantity was three times greater than that of females in July and August. Most females in June were primiparous and would become multiparous females in July and August with higher size-specific fecundity. Our study is the first to pair individual fecundity, stored sperm quantity, and spawning history for blue crabs, which allows for a robust assessment of reproductive potential. Generally, the reproductive potential of individual female blue crabs was high at the individual level, such that sperm limitation is unlikely at the population level. Population-level production may be increased by protecting primiparous spawners as these crabs have the highest capacity to contribute offspring to the population. Furthermore, fisheries management may be improved by using our updated estimate of size-specific fecundity (Fecundity = 268,337 × exp(0.015 × Carapace Width)) and incorporating month or spawner history in models of stock production.

Sex- and caste-specific developmental responses to juvenile hormone in an ant with maternal caste determination.

Juvenile hormone is considered to be a master regulator of polyphenism in social insects. In the ant Cardiocondyla obscurior, whether a female egg develops into a queen or a worker is determined maternally and caste-specific differentiation occurs in embryos, so that queens and workers can be distinguished in a non-invasive manner from late embryogenesis onwards. This ant also exhibits two male morphs - winged and wingless males. Here, we used topical treatment with juvenile hormone III and its synthetic analogue methoprene, a method that influences caste determination and differentiation in some ant species, to investigate whether hormone manipulation affects the development and growth of male, queen- and worker-destined embryos and larvae. We found no effect of hormone treatment on female caste ratios or body sizes in any of the treated stages, even though individuals reacted to heightened hormone availability with increased expression of krüppel-homolog 1, a conserved JH first-response gene. In contrast, hormone treatment resulted in the emergence of significantly larger males, although male morph fate was not affected. These results show that in C. obscurior, maternal caste determination leads to irreversible and highly canalized caste-specific development and growth.

Genetic Foundation of Male Spur Length and Its Correlation with Female Egg Production in Chickens.

Spurs, which mainly appear in roosters, are protrusions near the tarsometatarsus on both sides of the calves of chickens, and are connected to the tarsometatarsus by a bony core. As a male-biased morphological characteristic, the diameter and length of spurs vary significantly between different individuals, mainly related to genetics and age. As a specific behavior of hens, egg-laying also varies greatly between individuals in terms of traits such as age at first egg (AFE), egg weight (EW), and so on. At present, there are few studies on chicken spurs. In this study, we investigated the inheritance pattern of the spur trait in roosters with different phenotypes and the correlations between spur length, body weight at 18 weeks of age (BW18), shank length at 18 weeks of age (SL18), and the egg-laying trait in hens (both hens and roosters were from the same population and were grouped according to their family). These traits related to egg production included AFE, body weight at first egg (BWA), and first egg weight (FEW). We estimated genetic parameters based on pedigree and phenotype data, and used variance analysis to calculate broad-sense heritability for correcting the parameter estimation results. The results showed that the heritability of male left and right spurs ranged from 0.6 to 0.7. There were significant positive correlations between left and right spur length, BW18, SL18, and BWA, as well as between left and right spur length and AFE. We selected 35 males with the longest spurs and 35 males with the shortest spurs in the population, and pooled them into two sets to obtain the pooled genome sequencing data. After genome-wide association and genome divergency analysis by FST, allele frequency differences (AFDs), and XPEHH methods, we identified 7 overlapping genes (CENPE, FAT1, FAM149A, MANBA, NFKB1, SORBS2, UBE2D3) and 14 peak genes (SAMD12, TSPAN5, ENSGALG00000050071, ENSGALG00000053133, ENSGALG00000050348, CNTN5, TRPC6, ENSGALG00000047655,TMSB4X, LIX1, CKB, NEBL, PRTFDC1, MLLT10) related to left and right spur length through genome-wide selection signature analysis and a genome-wide association approach. Our results identified candidate genes associated with chicken spurs, which helps to understand the genetic mechanism of this trait and carry out subsequent research around it.

Fast discrimination of female and male pigeon eggs using internet of things in combined with Vis-NIR spectroscopy and chemometrics

In livestock industry, the female and male pigeons have different follow-up functions. The discrimination of female and male pigeons is an intensive concern for breeding tasks. In daily cultivation, the livestock staffs cannot distinguish the pigeon sex until the child pigeon is born. This lag in judgment seriously affects the freshness of pigeon eggs and timely sales plans. To solve this problem, we construct an internet of things (IoT) framework for modeling to discriminate a batch of pigeon eggs based on the instant data detection by visible and near-infrared (Vis-NIR) spectroscopy technology. In practice, the spectral detection data is monitored by multi-locational Vis-NIR sensors and immediately delivered to the cloud unit of the IoT framework. A random weight neural network (RWNN) architecture is designed as the intelligent computing module for model training and optimization, so that the cloud unit is able to deal with the constant inflow of Vis-NIR big data. An adaptive learning strategy is also designed to tune the network linkage weights as well as relevant hyperparameters. Partial least squares discriminant analysis is embedded in the Softmax unit for model discrimination, to optimize data processing with spectral properties. Experimental results proves that the adaptive RWNN architecture is able to observe high prediction accuracy when modeling on the early 5th-, 6th-, 7th- and 8th- hatching days for the distinguishment of the female and male pigeon eggs. Thus, the IoT-based Vis-NIR technology is prospectively expected to process the online big data in support with the adaptive RWNN modeling architecture.

Plant-level establishment can result from a single female Acanthococcus lagerstroemiae propagule

Crapemyrtle bark scale (CMBS), Acanthococcus lagerstroemiae (Kuwana) (Hemiptera: Eriococcidae), is a non-native scale insect that has spread throughout many urban areas of the Southeast and Middle Atlantic regions of the United States following its initial detection near Dallas, Texas in 2004, severely reducing the aesthetic value and health of the popular ornamental crapemyrtle tree (Lagerstroemia spp.). We infested crapemyrtles with known numbers of CMBS to determine the minimum number of individuals required for establishment after initial arrival on plants. We also investigated how netting—implemented to understand differences in establishment when scale dispersal and predation are inhibited—influenced population growth. We determined that one female CMBS egg sac can successfully establish a new population ~ 92% of the time and that netting had negligible effects on establishment. Our results underscore the importance of surveying and managing CMBS and scale insects with similar biology when attempting to prevent infestation of nursery stock, which is widely implicated as a vector for long-distance dispersal of scale insects.

Long-term suitability of an alternative host for rearing the sugarcane stalk borer parasitoid Tetrastichus howardi.

The continuous utilisation of an alternative host may influence parasitoid performance across successive generations due to conditioning in natal hosts. Tetrastichus howardi (Olliff) has successfully been reared using Tenebrio molitor L. pupae as a feasible alternative host. However, the extended rearing of T. howardi on this alternative host may impact the biological features of the parasitoids. Parasitoids were reared using T. molitor pupae for 30 consecutive generations. Quality criteria were assessed during the generations F5, F15, and F30, offering pupae of the target pest, Diatraea saccharalis (Fabr.), and compared with the F0 generation (parasitoids reared in D. saccharalis pupae). Criteria included assessments of parasitism performance, host selection, and wing form variation in the parasitoid wasps. Additionally, we examined the fecundity of T. howardi females that emerged from both hosts, considering their age, egg loading before and after one oviposition, as well as parasitism of sugarcane stalk borer pupae. Rearing T. howardi using pupae of T. molitor did not affect its biological traits or preference for the target pest for 30 generations. After parasitism, the parasitoid left the host pupa inside the stalk, and one oviposition was enough to kill D. saccharalis pupae and obtain viable parasitoid progeny. Female sexual maturation and egg loading occurred 72 and 96 h after parasitoid emergence. Egg-loading recovery after parasitism did not happen within 24 h. T. howardi can be reared for up to 30 generations using alternative hosts without compromising its parasitism performance or egg loading.

Влияние смещения половых циклов на репродуктивные характеристики самок сибирского осетра и рыбоводно-биологические характеристики молоди

Modern industrial fish farms have specialised fish-breeding equipment that allows them to artificially regulate fish rearing, such as getting spawners into a pre-spawning stage at the time required by fish farmers. In this context, there has been some interest in determining the effect of rearing conditions and husbandry of Siberian sturgeon spawners on the progeny. Various abiotic and biotic environmental factors were modelled using the test sites of the Branch for Freshwater Fisheries of the Russian Federal Research Institute of Fisheries and Oceanography (RFRIFO). Female Siberian sturgeons of the sixth domestication generation of 2008 were used in the experiments. Weight gain has a positive effect on relative and individual fecundity in females. Relative fecundity decreases after resorption. Female eggs get larger with age, however the difference in body weight of juveniles produced from smaller eggs after growing is only 13%. Throughout the rearing period, the condition factor in juveniles ranges from 0.088 to 0.094, representing 46.3-49.4% of the maximum value. When comparing the rearing conditions in all groups of females, no correlation was found between the duration of interspawning interval (285 or 600 days) and the thermal constant during this period (4.970-5.124 and 10.095 degree days) and relative fecundity. According to the studies, a shift in the timing of gametogenesis caused by a force majeure has no effect on reproductive product quality and the ensuing progeny.

The Role of Plant Defense Signaling Pathways in Phytoplasma-Infected and Uninfected Aster Leafhoppers' Oviposition, Development, and Settling Behavior.

In plant-microbe-insect systems, plant-mediated responses involve the regulation and interactions of plant defense signaling pathways of phytohormones jasmonic acid (JA), ethylene (ET), and salicylic acid (SA). Phytoplasma subgroup 16SrI is the causal agent of Aster Yellows (AY) disease and is primarily transmitted by populations of aster leafhoppers (Macrosteles quadrilineatus Forbes). Aster Yellows infection in plants is associated with the downregulation of the JA pathway and increased leafhopper oviposition. The extent to which the presence of intact phytohormone-mediated defensive pathways regulates aster leafhopper behavioral responses, such as oviposition or settling preferences, remains unknown. We conducted no-choice and two-choice bioassays using a selection of Arabidopsis thaliana lines that vary in their defense pathways and repeated the experiments using AY-infected aster leafhoppers to evaluate possible differences associated with phytoplasma infection. While nymphal development was similar among the different lines and groups of AY-uninfected and AY-infected insects, the number of offspring and individual female egg load of AY-uninfected and AY-infected insects differed in lines with mutated components of the JA and SA signaling pathways. In most cases, AY-uninfected insects preferred to settle on wild-type (WT) plants over mutant lines; no clear pattern was observed in the settling preference of AY-infected insects. These findings support previous observations in other plant pathosystems and suggest that plant signaling pathways and infection with a plant pathogen can affect insect behavioral responses in more than one manner. Potential differences with previous work on AY could be related to the specific subgroup of phytoplasma involved in each case.

Wolbachia Infection through Hybridization to Enhance an Incompatible Insect Technique-Based Suppression of Aedes albopictus in Eastern Spain.

The emergence of insecticide resistance in arbovirus vectors is putting the focus on the development of new strategies for control. In this regard, the exploitation of Wolbachia endosymbionts is receiving increasing attention due to its demonstrated effectiveness in reducing the vectorial capacity of Aedes mosquitoes. Here, we describe the establishment of a naïve Wolbachia infection in a wild Aedes albopictus population of eastern Spain through a hybridization approach to obtain males capable of sterilizing wild females. The obtained lines were compared with the Wolbachia donor, Ae. albopictus ARwP, previously artificially infected with Wolbachia wPip, regarding immature and adult survival, female fecundity, egg fertility, and level of induced sterility. Our results did not show significant differences between lines in any of the biological parameters analyzed, indicating the full suitability of the hybrids to be used as a control tool against Ae. albopictus. In particular, hybrid males induced 99.9% sterility in the eggs of wild females without the need for any preliminary treatment. Being harmless to non-target organisms and the environment, the use of this bacterium for the control of Ae. albopictus deserves further exploration. This is especially relevant in areas such as eastern Spain, where this mosquito species has recently spread and may represent a serious threat due to its competence as a vector for dengue, chikungunya, and Zika viruses.

Hydration state does not affect selected body temperature during gravidity or gravidity duration in pythons (Antaresia childreni)

The embryonic development of many ectothermic species are highly sensitive to temperature and typically have a higher thermal optima than do most other physiological processes. Thus, female ectotherms often maintain a higher and more carefully controlled body temperature when she is supporting developing embryos (early development in oviparous species, throughout development in viviparous species). Considering the positive correlation between body temperature and evaporative water loss, this response could potentially exacerbate female water imbalance in water-limited environments, suggesting that female water balance and egg development may be in conflict. Using Children's pythons (Antaresia childreni), we hypothesized that water deprivation reduces thermophily during gravidity. We split reproductive females into two thermal treatments: those provided with a continuously available thermal gradient of 25–45 °C and those kept at a constant 31 °C. We also had seven non-reproductive females that were provided a thermal gradient. Within each thermal treatment group, we alternatingly assigned females to either have or not have water throughout gravidity. We found that reproduction increased female body temperature, but this increase was not affected by water regime. Reproduction also increased plasma osmolality, and lack of water during gravidity exacerbated this effect. We also found that thermal treatment, but not water regime, significantly influenced gravidity duration, with females given a thermogradient having a shorter gravidity duration, likely as a result of having a higher average body temperature than did the females provided constant heat. Finally, we found that females provided water throughout gravidity had greater clutch masses than did females without water. Further research is needed to improve scientific understanding of the interactions among water balance, body temperature, and various physiological performances.

An improved medium for in vitro studies of female reproduction and oviposition in Schistosoma japonicum

BackgroundSchistosomiasis is a disease primarily caused by eggs laid by pathogens called schistosomes. Among the schistosome species infecting humans, Schistosoma japonicum possesses the largest fecundity; each adult female produces an average of 3500 eggs per day. The lack of proper culture conditions supporting continuous oviposition in vitro has precluded detailed investigation of mechanisms regulating sexual maturation and egg production in Schistosoma japonicum.MethodsWe optimized in vitro culture conditions by replacing reagents that are part of the classical ABC169 medium. Fast Blue BB staining and 4′,6-diamidino-2-phenylindole (DAPI) labeling were applied to observe the sexual development status of the females. In vitro RNA interference (RNAi) technology was used to validate the capability of the modified medium. The detection of male β-alanyl-tryptamine (BATT) was conducted using liquid chromatography–mass spectrometry (LC–MS).ResultsBoth m-AB169 (1640) and AB169 (1640) media are capable of facilitating the sexual development of paired virgin female S. japonicum, as well as sustaining the mature reproductive organs and egg production of adult S. japonicum for at least 22 days in vitro. M-AB169 (1640) provided a more stable condition for supporting the sexual maturity of female S. japonicum, as evidenced by the consistent initiation of egg production compared with AB169 (1640). Through a comparative analysis of S. japonicum and S. mansoni in diverse media, we demonstrated that these closely related species display distinct demands for their sexual development and egg production, suggesting a potential influence of nutritional factors on the observed variations in host ranges among different schistosome species. Importantly, we successfully identified the presence of the pheromone β-alanyl-tryptamine (BATT) in S. japonicum, previously identified in S. mansoni, highlighting its conserved role in schistosome reproductive development. Through the employment of double-stranded RNA (dsRNA) treatment to silence two genes that are involved in either the male (gli1, glioma-associated oncogene homolog 1) or female (vf1, vitellogenic factor 1) side in male-induced female reproductive development of S. mansoni, we confirmed that the combination of m-AB169 (1640) and RNAi technology has the capacity to facilitate in vitro studies of S. japonicum’s reproductive and oviposition processes.ConclusionsWe developed a novel medium, m-AB169 (1640), that not only maintains the mature reproductive organs and continuous oviposition of adult female Schistosoma japonicum for up to 22 days but also supports the reproductive development and subsequent egg-laying of virgin females after pairing with male worms. This study provides a valuable in vitro platform for functional studies of the mechanisms underlying the fascinating biology of the female sexual development and egg production of S. japonicum, which may accelerate the development of new strategies targeting schistosome egg production.Graphical

Variation in Paramarteilia canceri infections in velvet crab Necora puber.

Sustainable management of crustacean populations requires an understanding of the range of factors affecting different crustacean species. Recently, a high prevalence of a paramyxid parasite, Paramarteilia canceri, was reported in velvet crabs Necora puber in Ireland. Similar parasites have been known to cause mass mortalities in bivalves and, as velvet crabs are an important commercial species, these parasite infections are cause for concern. The main objective of this study was to examine variation in P. canceri infections in relation to host biology and season over a 2 yr period. In addition, we tested a range of host tissues and organs to gain more information on the host-parasite interaction. The parasite was present in all tissues and organs investigated, including the gonad and eggs of a berried female. Parasite prevalence was highest in the cuticular epithelium and hepatopancreas. Both annual and seasonal variation was found in parasite prevalence and parasite load. No difference was found in parasite prevalence or parasite load with either crab size or crab sex. Granulomas as a response to infection were significantly more abundant in infected velvet crab individuals. The results of this study provide important information on the host-parasite interaction between P. canceri and the velvet crab and highlight the importance of including parasite monitoring in the management of crustacean fisheries.