Vitellogenin Gene Expression Research Articles

Effect of autoantibody against follicle stimulating hormone (Fsh) induced by DNA vaccine in rainbow trout Oncorhynchus mykiss

In this study, effects of DNA vaccine encoding rainbow trout (Oncorhynchus mykiss) follicle stimulating hormone (Fsh) gene (pCI-Fsh) was evaluated. pCI-Fsh was injected into the fish to analyze the specific antibody titer against Fsh and sexual maturation. The antibody titer against Fsh in the vector-injected fish was significantly higher than those in the PBS-injected fish at 13 and 146 days after injection. On the other hand, vitellogenin gene expression levels in the female fish and 11-ketoteststeron concentration in the male fish were not significantly different between the vector- and PBS-injected fish. In addition, gonad somatic index and body weight of the trout were not significantly different between the fish. These results suggested that the autoantibody induced by pCI-Fsh was not sufficient to inhibit sex steroidogenesis in the trout.

Doublesex homolog is sex-specifically spliced and governs the sexual differentiation process in the whitefly Bemisia tabaci AsiaII-1

The silverleaf whitefly Bemisia tabaci is one of the most destructive of crop pests globally. In Northern India cotton is predominately infested by the Asia II-1 species of B. tabaci. Though B. tabaci exhibits unique haplodiploidy in its reproductive behavior, to date very little is known regarding its sex determination mechanism. Here, an in-depth characterization of the AsiaII-1 doublesex (Btdsx) gene, which has been implicated in sex determination in B. tabaci, indicates the inclusion of six exons and five introns. The pre-mRNA is shown to sex-specifically splice, producing four male isoforms and one female isoform. These BtDsx proteins share common DNA binding (OD1) domains whereas they differ at their C-termini. RT-qPCR analysis revealed a significantly higher expression of Btdsx in female adults compared to that in male adults and earlier developmental stages. Functional characterization of Btdsx through RNA interference (RNAi) resulted in a significant reduction in its expression in both sexes. Btdsx knockdown concomitantly resulted in up-regulation of the expression of vitellogenin (vg) and vitellogenin receptor (vgr) genes in males and their down-regulation in females. Btdsx knockdown followed by mating resulted in reduced fecundity and percent egg hatching; however, no impact was observed on the female: male ratios in the progeny obtained from knockdown parents.

Shrimp shell waste-derived astaxanthin in synergistic combination with its commercial variant augments gonadal maturation and upregulates vitellogenin gene expression of discus (Symphysodon aequifasciatus)

A study was performed to evaluate the efficacy of shrimp shell meal derived natural astaxanthin (SSM), supplemented with its commercial variant on gonadal maturation and vitellogenin gene (Vtg.) expression in reproductively active adults of the high-value ornamental cichlid discus (Symphysodon aequifasciatus) reared under captivity. Four isonitrogenous (50% crude protein), isolipidic (9% ether extract), and isocaloric (400 kcal digestible energy/100 g) experimental diets viz. control (commercial grade astaxanthin, without SSM), T1 (15% SSM + commercial astaxanthin), T2 (20% SSM + commercial astaxanthin), T3 (25% SSM + commercial astaxanthin) were prepared and fed to satiation level twice daily for the entire experimental period of 90 days. Results revealed significant (p < 0.05) linear, quadratic, and overall trends, wherein GSI increased with an increase in the proportion of SSM in the diet, with higher GSI recorded in T2 and T3 treatment groups (testis and ovary, respectively), which were significantly (p < 0.05) different from other groups. The overall linear and quadratic trends of HSI differed significantly (p < 0.05) with the variability in proportions of natural and commercial astaxanthin combinations and were found highest in the T2 treatment group. Cholesterol, FSH, LH, 11-KT, 17β- Estradiol, and 17α-20β DHP levels increased with an increasing proportion of natural astaxanthin and recorded the highest values in the treatment T2 with an overall significant linear and quadratic trend as compared to other treatments. Most of the oocytes of T2 and T3 groups were in the vitellogenic phase, i.e., primary, secondary, and tertiary yolk stages. More spermatids were visible in testicular tubules in T2, followed by T3 and T1. The abundance of Vtg. mRNA was significantly (p < 0.05) evident in T2, followed by T1, then in control. Further increase in SSM inclusion caused a downregulation in the expression of this gene in the T3 group. The dietary combination of SSM @200 g/kg diet with its synthetic/commercial variant exhibited optimum performance at combination levels of 77.5 and 22.5 mg/kg, respectively, evidenced in terms of changes in steroid hormone profiles, gonadal maturation and vitellogenin gene expression in comparison to the control, which contained the dietary synthetic/commercial variant of astaxanthin alone. These inferences are presumably a milestone in the captive broodstock development of this high-value ornamental cichlid, S. aequifasciatus, with an added advantage of cost-effectiveness. The study would help the utilisation of economically important bio-waste in combination with commercial variants for effective value addition in the ornamental fish feed industry.

Ultra Violet (UV-B) radiation intrudes Cadra cautella reproductive biology by influencing vitellogenin expression

ObjectiveDate palm is a very important fruit crop growing in the world's warm climate. Several pests attack date fruit in the field and in storage. The almond moth, Cadra cautella, is a primary key pest which damages date fruits. Present research shows ultraviolet irradiation effect on mortality and reproduction of C. cautella female larval and female pupal stages in the laboratory. MethodsFemale larva aged 18 days and female pupae aged 1–2 days, were directly exposed to ultra violet (UV) type B in a chamber for 0, 2, 4, 6, and 12 h. Mortality of treated larvae and pupae was calculated and compared with the 0 h treatment (control). To quantify vitellogenin gene expression through real time polymerase chain reaction (RT-qPCR), larvae and pupae samples were collected from each treatment after each exposure interval and preserved at −80 °C. ResultsCadra cautella larvae and pupae, were vulnerable to the UV and the mortality was observed for all exposure intervals showing the highest mortality rate of 90 % larval mortality at 12 exposure interval. Whereas, in case of pupal mortality, 72.26 % mortality was observed after 12 h of exposure intervals. The UV-treated female pupae that survived the pupal developmental stage and emerged as adult moths were not healthy and were mostly deformed, preventing them from emerging from the puparium. Furthermore, when treated female moths emerged, they were unable to copulate with normal male moths, resulting in fewer unfertile eggs. In addition, the lethal effects of UV on vitellogenin gene expression in treated larvae and pupae were confirmed using real-time PCR, the results confirmed that UV had a harmful effect on vitellogenin gene expression. ConclusionsThe current study results are highly encouraging and may be useful in suppressing C. cautella populations in storages and managing this renowned pest of stored date fruits and other agricultural commodities on an industrial/commercial scale.

Chlorella-supplemented diet improves the health of honey bee (Apis mellifera)

Nutritional stress is one of the major factors affecting the health of honey bees. Supplementing the pollen patty with microalgae enhances the protein content of the patty and therefore is supposed to improve bee’s health. The objective of the present study was to investigate the effect of Chlorella as a dietary supplement on the health and physiology of the honey bee (Apis mellifera). We formulated the honey bee feed by supplementing Chlorella sorokiniana, obtained commercially, with commercially available rapeseed pollen patty in different amounts—0.5, 2, 5, and 10%, and the treatment groups were named P0.5, P2, P5, and P10, respectively. Pollen patty was set as a positive control and only 50% sucrose solution (no protein) was set as a negative control. Diets were supplied ad libitum to newly emerged workers in cages; food consumption patterns; longevity; and physiology including the development of the brain in terms of protein (i.e., total amino acids), thorax muscle, fat body mass, and glands (hypopharyngeal and venom); and gene expression of nutrition-related gene vitellogenin (Vg) of honey bee at different points of time of their age were observed. The addition of Chlorella significantly increased the food consumption pattern, longevity, gland development, muscle formation, and Vg gene expression significantly in comparison to only a pollen or sugar diet. However, the response varied depending on the level of Chlorella supplementation. As depicted in most of the cases, P2, that is, the pollen diet with 2% of Chlorella supplement exhibited the best outcome in terms of all the tested parameters. Therefore, based on the results obtained in the present study, we concluded that 2% Chlorella supplementation to pollen patty could enhance the health of honey bees, which in turn improves their performance.

Role of vitamin a in the ovary development for female Eriocheir sinensis in the gonadal development stage

This study aimed to test the regulatory role of vitamin A in the vitellogenesis of female Eriocheir sinensis. Three diets containing a gradient of vitamin A level (0-control, 8000 and 30,000 IU/kg) were fed to female crabs (74.44 ± 0.81 g) for 90 days. Compared to the vitamin A devoid group, 8000 IU/kg of dietary vitamin A increased the content of hemolymph ecdysone, vitellogenin levels and the gonadosomatic index. The 8000 IU/kg vitamin A level induced vitellogenin (vtg) gene expression in the ovary and hepatopancreas. The vtg gene expression was induced by upregulating retinoid x receptor, ecdysone receptor, ecdysteroid responsive gene E75 and vitellogenin receptor. Lipid accumulation was also improved for ovarian development. Hepatosomatic index and lipid accumulation in the hepatopancreas and ovary were increased by 8000 IU/kg vitamin A supplement relative to the control. The 8000 IU/kg vitamin A diet upregulated the gene expressions in lipid uptake, synthesis and export, but downregulated the genes related to catabolism in the hepatopancreas. Only genes related to lipid uptake were positively influenced by 8000 IU/kg of vitamin A in the ovary. Furthermore, proper vitamin A could improve the health of crabs by enhancing their antioxidant capacity and immunity. In contrast, a negative effect on hepatopancreas antioxidant ability, lipid metabolism and vitellogenesis was found due to an excess vitamin A supplement (30,000 IU/kg) compared to 8000 IU/kg of dietary vitamin A. This study indicates the necessity of vitamin A supplements in formulated diets because they can optimize lipid metabolism and promote vitellogenesis during ovarian development.

PGE2 mediation of egg development in Western flower thrip, Frankliniella occidentalis.

Eicosanoids mediate various insect physiological processes, including reproduction. Especially, the eicosanoid prostaglandin E2 (PGE2 ) is known to mediate oocyte development in some insects. The explosive reproductive potential of the Western flower thrips, Frankliniella occidentalis, damages various agricultural crops. However, little is known about the underlying physiological processes of egg development in this pest. This study found that treatment with aspirin (ASP) (a specific cyclooxygenase (COX) inhibitor) used to inhibit PGE2 biosynthesis during ovarian development significantly suppressed the reproduction of female F. occidentalis. However, the addition of PGE2 to ASP-treated females significantly rescued the suppressed reproduction. PGE2 was detected in growing ovarian follicles in an immunofluorescence assay. The hypothetical biosynthetic machinery of PGE2 was predicted from the F. occidentalis genome and included phospholipase A2 (PLA2 ), COX-like peroxidase (POX), and PGE2 synthase (PGES). Three specific PLA2 s were highly expressed in female adults during active oogenesis. Specific POX and PGES genes also showed high expression during active oogenesis. The adverse effect of ASP treatment on oogenesis was observed in follicle formation in the germarium where the follicle numbers in an ovariole were decreased, which resulted in hypotrophied ovaries. This impairment was rescued by the addition of PGE2 . ASP treatment also significantly inhibited chorion formation and suppressed gene expression associated with choriogenesis, which included chorion protein, mucin, and yellow while it did not inhibit vitellogenin gene expression. However, the addition of PGE2 induced the expression of the target genes suppressed by ASP treatment and rescued chorion formation. These results suggest that PGE2 mediated ovarian development by affecting follicle formation and choriogenesis in F. occidentalis.

Effect of Swimming on the Induction of Vitellogenin in Conger Eel (Conger myriaster)

Vitellogenin (VTG) plays a very important role in the development of oocytes. This study aims to explore the effect of swimming on the VTG synthesis of conger eel (Conger myriaster). Circulating water flow and hormone injection regimen were two factors set in the following trials: A1 (no injection, no water flow), A2 (no injection, water flow), B1 (injection, no water flow), and B2 (injection, water flow). The flow velocity of the flowing water was 0.4 m/s (12 h, 60 days). We examined VTG, estrogen receptor (Er) gene expression, and VTG content in the liver and serum on the 30th and 60th days. VTG gene expression in A1 and A2 gradually decreased and was not significantly different between the two groups. The expression of Er gene in A1 was significantly higher than that in A2. The expression of VTG gene in group B1 was significantly higher than that in group B2, whereas the expression level of Er gene in group B1 was slightly higher than that in group B1. The VTG content in the liver in group B1 reached 1,396.93 μg/L, which was significantly higher than that in group B2 (1,302.06 μg/L). Results showed that the flowing water factor can inhibit the expression of VTG and Er genes in the liver and reduce the synthesis of VTG in the liver. Stimulation of flowing water can inhibit the yolk accumulation during the ovarian development of conger eel.

Expression and Role of Vitellogenin Genes in Ovarian Development of Zeugodacus cucurbitae.

Simple SummaryVitellogenin (Vg) is the precursor of the yolk protein gene, which is crucial for insect reproduction. In this study, we identified four Vg genes in Zeugodacus cucurbitae (Coquillett). Their molecular characteristics and expression patterns were analyzed. The four genes are mainly expressed in the fat body tissue of adult female melon flies, and their expression is regulated by the juvenile hormone and ecdysone. Nutritional stress significantly down-regulated their expression, indicating that nutrition-dependent vitellogenic development occurs during ovarian development. RNAi-mediated inhibition of the expression of the four genes resulted in significantly delayed ovarian development in Z. cucurbitae. The results indicate that the four genes play an important role in the development of ovaries in Z. cucurbitae.Vitellogenin (Vg) genes encode the major egg yolk protein precursor in arthropods. In this study, four Vgs were identified in Zeugodacus cucurbitae (Coquillett). Sequence analysis showed that four ZcVgs had the conserved Vg domain. Phylogenetic analysis indicated that four ZcVgs were homologous to the Vgs of Tephritidae insects. The temporal and spatial expression patterns of ZcVgs were analyzed by quantitative real-time polymerase chain reaction (RT-qPCR), and the four ZcVgs showed high expression levels in female adults, especially in the fat body. The expression of ZcVg1 and ZcVg3 was down-regulated by a low dosage (0.5 μg) of 20-hydroxyecdysone (20E), and ZcVg2, ZcVg3, and ZcVg4 were up-regulated by a high dosage (1.0 and 2.0 μg) of 20E. The expression of ZcVg1 and ZcVg2 was up-regulated by 5 μg of juvenile hormone (JH), while all of the ZcVgs were down-regulated by a low and high dosage of JH. Expression of ZcVgs was down-regulated after 24 h of starvation and recovered to normal after nutritional supplementation. After micro-injection of the gene-specific double-stranded RNA, the ZcVgs’ expression was significantly suppressed, and ovarian development was delayed in Z. cucurbitae females. The results indicate that RNA interference of reproduction-related genes is a potential pest control method that works by manipulating female fertility.

Alternative Splicing of the Lobster (Homarus americanus) Crustacean Hyperglycemic Hormone A and B Genes Produce 2 Protein Variants Involved in Vitellogenin Inhibition

Current BLASTP search analysis results suggested that the lobster (Homarus americanus) HaCHH-A and HaCHH-B may be derived from two different four-exon genes. Repeated tissue expression studies have revealed much different expression patterns of these two genes from those reported in the past. With RT-PCR, rapid amplification of complementary DNA (cDNA) ends (RACE), and genomic DNA cloning, we confirmed that the HaCHH-A and HaCHH-B transcripts were derived from two different four-exon CHH genes. By an alternative splicing mechanism, each gene can produce different but larger transcript variants (i.e., sHaCHH-A and sHaCHH-B) mainly in different non-eyestalk tissues of the females. The larger and unspliced transcripts can be detected in the hepatopancreas, gill, heart, nerve cord, brain, ovary, and thoracic ganglion of the reproductive females. The expression patterns of sHaCHH-A and sHaCHH-B in other non-eyestalk tissues suggest that these transcripts have a wide spectrum of expressions during the female reproductive cycle. An in vitro organ explant culture system was developed to investigate the reproductive function of these cDNAs. The results showed that the recombinant proteins for sHaCHH-A and sHaCHH-B inhibited the gene expression of vitellogenin, whereas the double-stranded RNA (dsRNA) for sHaCHH-A and sHaCHH-B stimulated the expression of the vitellogenin gene in vitro. The results of the study may provide insights for the development of techniques to induce gonad development without using eyestalk ablation operation. This is the first in-depth report of the characterization of two four-exon CHH genes in a crustacean.

Selection of stable reference genes for quantitative real-time PCR in the Varroa mite, Varroa destructor.

To investigate the acaricide toxicity and resistance mechanisms in the Varroa mite, it is essential to understand the genetic responses of Varroa mites to acaricides, which are usually evaluated by transcriptional profiling based on quantitative real-time polymerase chain reaction(qPCR). In this study, to select reference genes showing consistent expression patterns regardless of the acaricide treatment or the type of tissue, Varroa mites treated with each of the three representative acaricides (coumaphos, fluvalinate, and amitraz) were processed for transcriptomic analysis, from which eight genes (NADH dehydrogenase[NADHD], glyceraldehyde-3-phosphate dehydrogenase[GAPDH], eukaryotic translation elongation factor 1 α 1[eEF1A1], eukaryotic translation elongation factor 2[eEF2], ribosomal protein L5[RpL5], Actin, tubulin α-1D chain[α-tubulin], and Rab1) were selected as candidates. The transcription profiles of these genes, depending on the treatment of the three acaricides or across different tissues (cuticle, legs, gut/fat bodies, and synganglion), were analyzed using qPCR with four validation programs, BestKeeper, geNorm, NormFinder, and RefFinder. Following acaricide treatment, eEF1A1 and NADHD showed the least variation in their expression levels, whereas the expression levels of α-tubulin and RpL5 were the most stable across different tissue groups. Rab1/GAPDH and Actin/eEF2 showed the least stable expression patterns following acaricide treatments and across different tissues, respectively, requiring precautions for use. When vitellogenin gene expression was analyzed by different reference genes, its expression profiles varied significantly depending on the reference genes, highlighting the importance of proper reference gene use. Thus, it is recommended using eEF1A1 and NADHD as reference genes for the comparison of the effects of acaricide on the whole body, whereas α-tubulin and RpL5 are recommended for investigating the tissue-specific expression profiles of target genes.

Bisphenol B disrupts testis differentiation partly via the estrogen receptor-mediated pathway and subsequently causes testicular dysgenesis in Xenopus laevis

There is growing concern about adverse effects of bisphenol A alternatives including bisphenol B (BPB) due to their estrogenic activity. However, limited data are available concerning the influences of BPB on male reproductive development in vertebrates, especially in amphibians, which are believed to be susceptible to estrogenic chemicals. The present study investigated the effects of 10, 100 and 1000 nM BPB (2.42, 24.2 and 242 μg/L) on testis development in Xenopus laevis, a model amphibian species for studying gonadal feminization. We found that exposure to BPB from stages 45/46 to 52 resulted in down-regulation of testis-biased gene expression and up-regulation of ovary-biased gene and vitellogenin (vtgb1) expression in gonad-mesonephros complexes (GMCs) of tadpoles at stage 52, coupled with suppressed cell proliferation in testes and reduced gonadal metameres, resembling the effects of 17ß-estradiol. Moreover, an estrogen receptor (ER) antagonist ICI 182780 antagonized BPB-caused up-regulation of ovary-biased gene and vtgb1 expression to some degree, indicating that the effects of BPB on X. laevis testis differentiation could be partly mediated by ER. All observations demonstrate that early exposure to BPB inhibited testis differentiation and exerted certain feminizing effects during gonadal differentiation. When exposure was extended to post-metamorphosis, testes exhibited histological and morphological abnormalities including segmented, discontinuous and fragmented shapes, besides altered sex-dimorphic gene expression. Notably, most of BPB-caused alterations were not concentration-dependent, but the lowest concentration indeed exerted significant effects. Overall, our study for the first time reveals that low concentrations of BPB can disrupt testis differentiation partly due to its estrogenic activity and subsequently cause testicular dysgenesis after metamorphosis, highlighting its reproductive risk to amphibians and other vertebrates including humans. Our finding also implies that estrogenic chemicals-caused testis differentiation inhibition at tadpole stages could predict later testicular dysgenesis after metamorphosis, meaning a possibility of early detection of abnormal testis development caused by estrogenic chemicals.

Environmentally relevant arsenic exposure affects morphological and molecular endpoints associated with reproduction in the Western mosquitofish, Gambusia affinis

Arsenic (As) exposure, even at low environmentally relevant levels, may cause detrimental health outcomes through developmental toxicity and by acting as an endocrine disrupting compound (EDC). Although several studies indicate that wildlife bioaccumulate As, few evaluate the health impact on fish species in their natural environment. In the U.S., As has a drinking water regulatory limit of 10 μg/L. In many parts of Arizona, surface water and groundwater have naturally elevated levels of As from geologic deposits and contamination is exacerbated by anthropogenic activity. In aquatic environments, the Western mosquitofish, Gambusia affinis, is a good bioindicator for EDC exposure because of the distinct androgen-related development of an intromittent organ, the gonapodium, in males. We evaluated morphological and reproductive outcomes in mosquitofish exposed to As. In a laboratory experiment, juvenile male mosquitofish were exposed to sodium arsenite (0 μg/L, 0.75 μg/L, 7.50 μg/L, and 75 μg/L) for 30 days, and in a field study, populations of adult male mosquitofish were collected in Arizona waterways with As levels above and below the World Health Organization's regulatory limit. In both studies, higher As exposure was significantly associated with altered hepatosomatic indices, altered fish morphology, shortened gonopodia, and lower gonopodia-somatic indices. In the field experiment, populations from surface water with higher As concentrations exhibited lower condition factors, lower gonadal-somatic indices, distinct gonopodia shapes, and altered estrogen receptor alpha and vitellogenin gene expression; androgen receptor expression was unchanged. Together, laboratory and field results suggest that As exposure at environmentally-relevant levels affects general growth and reproductive development in mosquitofish. Observed effects may further influence individual health, mobility, or reproductive function, and because G. affinis is a species known to tolerate and adapt to a wide range of environments, it serves as a local bioindicator species as well as a model organism for parallel field and laboratory studies.

Effect of yeast and essential oil-enriched diets on critical determinants of health and immune function in Africanized Apis mellifera.

Nutrition is vital for health and immune function in honey bees (Apis mellifera). The effect of diets enriched with bee-associated yeasts and essential oils of Mexican oregano (Lippia graveolens) was tested on survival, food intake, accumulated fat body tissue, and gene expression of vitellogenin (Vg), prophenoloxidase (proPO) and glucose oxidase (GOx) in newly emerged worker bees. The enriched diets were provided to bees under the premise that supplementation with yeasts or essential oils can enhance health variables and the expression of genes related to immune function in worker bees. Based on a standard pollen substitute, used as a control diet, enriched diets were formulated, five with added bee-associated yeasts (Starmerella bombicola, Starmerella etchellsii, Starmerella bombicola 2, Zygosaccharomyces mellis, and the brewers’ yeast Saccharomyces cerevisiae) and three with added essential oils from L. graveolens (carvacrol, thymol, and sesquiterpenes). Groups of bees were fed one of the diets for 9 or 12 days. Survival probability was similar in the yeast and essential oils treatments in relation to the control, but median survival was lower in the carvacrol and sesquiterpenes treatments. Food intake was higher in all the yeast treatments than in the control. Fat body percentage in individual bees was slightly lower in all treatments than in the control, with significant decreases in the thymol and carvacrol treatments. Expression of the genes Vg, proPO, and GOx was minimally affected by the yeast treatments but was adversely affected by the carvacrol and thymol treatments.

Endocrine disruption in the sub Antarctic fish Patagonotothen tessellata (Perciformes, Notothenidae) from Beagle Channel associated to anthropogenic impact

Situated in the sub-Antarctic region, Beagle Channel represents a unique marine ecosystem due to the connection between the Pacific and the Atlantic Oceans, and its proximity to the Antarctic Peninsula. Ushuaia city, the biggest settlement on the channel, exerts an increasing anthropogenic pressure by discharges of urban and industrial effluents. In the present work, we use Patagonotothen tessellata, one of the most abundant and widespread species in the channel, as a bioindicator species in order to evidence anthropic impact from Ushuaia Bay and surrounding areas. We first analyzed and characterized real time gene expression of androgen receptor, estrogen receptor and different forms of vitellogenin (VTG), under laboratory conditions. This was achieved by induction with estradiol of P. tessellata males. Then, the selected genes were used as biomarkers for an environmental biomonitoring study. Morphometric indices and circulating sex steroids (estradiol and testosterone) were also quantified in male fish collected from different sites. The qPCR analysis showed that vtgAb form is more inducible than vtgAa or vtgC forms after estrogen induction. The field survey revealed the up-regulation of vtgAb and the androgen receptor in fish from sites with higher anthropogenic influence. Sex steroids followed seasonal variations according to their reproductive cycle, with higher levels of estradiol and testosterone in winter and summer seasons. The use of biomarkers such as gene expression of VTG demonstrates that fish from Ushuaia Bay are likely to be exposed to endocrine disrupting compounds. To our knowledge, this research is the first attempt to assess the endocrine disruption associated to anthropic impact in a widespread fish of the Beagle Channel and contributes to a better understanding of the reproductive physiology of sub Antarctic ichthyofauna.

Pollen nutrition fosters honeybee tolerance to pesticides.

A reduction in floral resource abundance and diversity is generally observed in agro-ecosystems, along with widespread exposure to pesticides. Therefore, a better understanding on how the availability and quality of pollen diets can modulate honeybee sensitivity to pesticides is required. For that purpose, we evaluated the toxicity of acute exposure and chronic exposures to field realistic and higher concentrations of azoxystrobin (fungicide) and sulfoxaflor (insecticide) in honeybees provided with pollen diets of differing qualities (named S and BQ pollens). We found that pollen intake reduced the toxicity of the acute doses of pesticides. Contrary to azoxystrobin, chronic exposures to sulfoxaflor increased by 1.5- to 12-fold bee mortality, which was reduced by pollen intake. Most importantly, the risk of death upon exposure to a high concentration of sulfoxaflor was significantly lower for the S pollen diet when compared with the BQ pollen diet. This reduced pesticide toxicity was associated with a higher gene expression of vitellogenin, a glycoprotein that promotes bee longevity, a faster sulfoxaflor metabolization and a lower concentration of the phytochemical p-coumaric acid, known to upregulate detoxification enzymes. Thus, our study revealed that pollen quality can influence the ability of bees to metabolize pesticides and withstand their detrimental effects, providing another strong argument for the restoration of suitable foraging habitat.

Effects of cadmium on the female reproductive axis of a Neotropical fish

Metals are one of the contaminants released from the increase of anthropic activities. They can be classified as endocrine disruptors once they can affect the reproductive parameters of different organisms. The aim of the study was to evaluate the potential effects of cadmium on regulatory reproduction axis (Hypothalamic-Pituitary-Gonadal-Liver, the HPGL axis) in females of Rhamdia quelen exposed to nominal concentrations of 0.1; 1; 10 and 100 μg.L−1 of cadmium. After 15 days, tissues were collected for hormonal quantification, brain aromatase (cyp19a1b), hepatic vitellogenin (vtg) gene expression, and biomarkers analysis. Cadmium was quantified in water, gonad and liver samples. The plasma levels of estradiol, testosterone and gonad and hepatosomatic indexes did not changed after Cd exposure. The cyp19a1b was not different among the groups. Cadmium was detected at higher concentrations in the liver compared to the gonads. No genotoxicity was observed, only erythrocytes nuclear alterations. Metallothionein was reduced at 10 μg.L−1 in the liver and 10 and 100 μg.L−1 in the gonad. Hepatic superoxide dismutase activity increased and this can lead to a hydrogen peroxide increase, one of reactive oxygen species. This increase without a compensation of other enzymes of the antioxidant system can lead to lipoperoxidation, as occurred at 100 μg.L−1. Hepatic vitellogenin gene expression increased as well as the injury index at 0,1 and 100 μg.L−1. The tested cadmium concentrations have been found in the freshwater ecosystems and can affect the female reproductive regulation axis HPGL of the Neotropical species R. quelen.

Extra-Fortification of Zinc Upsets Vitellogenin Gene Expression and Antioxidant Status in Female of Clarias magur brooders.

The present experiment was designed to evaluate the effect of graded level of zinc on Vitellogenin gene (Vtg) expression and antioxidant enzymes in threatened catfish, Clarias magur (C. magur). One hundred and eighty female C. magur with an average weight of 145 ± 5g were allocated in twelve cemented tanks with dimension 4.5 × 2 × 1m for a period of 60days. Fish were distributed in four groups with three replicates following the completely randomised design. The first group treated as control (C) fed with basal diet contained normal zinc level, and remaining groups were fed with basal diets having 50, 200 and 300mg/kg zinc acetate and treated as T1, T2 and T3 respectively. To evaluate the effect of dietary zinc supplementation on Vtg gene expression, three sampling were carried out, I sampling (April, before starting the experimental trail), II sampling (May, after 1month of feeding trail) and III sampling (June before breeding season). In the present study, a dose-dependent relationship between Vtg gene expression and zinc inclusion in the diet of threatened catfish, C. magur, was reported. Vtg gene expression increased in all groups from I sampling to II sampling but the highest Vtg gene expression was found in T1 group and the lowest in T3 group at II sampling. Vtg gene expression among the treatments differs significantly (P < 0.05) in each sampling. Accumulation of zinc was measured by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) in C. magur and it was reported that the significantly higher (P < 0.05) zinc was accumulated in the liver and ovary of T3 group as compared to other groups. The antioxidant enzyme activities (superoxide dismutase, SOD, catalase and GST) were also measured in different tissues (liver, gill and ovary) to evaluate the effect of extra-supplementation of zinc on the antioxidant status. In T3 group, SOD, catalase and GST activities were significantly higher than those in other groups. In the current study, serum glucose level was also measured and it was found in increasing trend with inclusion of zinc in the diet of C. magur. In the present study, it can be concluded that the zinc exhibits beneficial effect only up to 50mg/kg. Thus, it is concluded that supplementation of zinc at 200mg/kg or more disrupts Vtg gene expression and antioxidant status.

An In Silico and In Vitro Study for Investigating Estrogenic Endocrine Effects of Emerging Persistent Pollutants Using Primary Hepatocytes from Grey Mullet (Mugil cephalus)

There is growing concern about the environmentally relevant concentrations of new emerging persistent organic pollutants, such as perfluorinated compounds and pharmaceuticals, which are found to bioaccumulate in aquatic organisms at concentrations suspected to cause reproductive toxicity due to the activation of estrogen receptor (ER) α and β subtypes. Here, we use a combined in silico and in vitro approach to evaluate the impact of perfluorononanoic acid (PFNA) and Enalapril (ENA) on grey mullet (Mugil cephalus) hepatic estrogen signaling pathway. ENA had weak agonist activity on ERα while PFNA showed moderate to high agonist binding to both ERs. According to these effects, hepatocytes incubation for 48 h to PFNA resulted in a concentration-dependent upregulation of ER and vitellogenin gene expression profiles, whereas only a small increase was observed in ERα mRNA levels for the highest ENA concentration. These data suggest a structure–activity relationship between hepatic ERs and these emerging pollutants.

RNAi Reveals Role of Insulin-Like Androgenic Gland Hormone 2 (IAG2) in Sexual Differentiation and Growth in Hermaphrodite Shrimp

Insulin-like androgenic gland hormone (IAG) is the most widely known hormone that regulates sexual differentiation in crustaceans. Previously, a transcriptome study described two transcripts of IAGs (Lvit-IAG1 and Lvit-IAG2) in the peppermint shrimp Lysmata vittata, a species characterized by a rare reproductive system of protandric simultaneous hermaphroditism (PSH). Herein, we explored the function of Lvit-IAG2 via RNA interference (RNAi) experiments, and then compared the functional differences between the two IAGs. We demonstrated that Lvit-IAG2 positively regulated the expression of crustacean hyperglycemic hormone (Lvit-CHH) in eyestalk ganglion but exhibited no significant effect on the expression of gonad-inhibiting hormone (Lvit-GIHs) and crustacean female sex hormone (Lvit-CFSHs). Besides, Lvit-IAG2 gene knockdown caused degeneration in appendices masculinae (AM) and suppressed germ cells at the secondary spermatocyte stage. Moreover, silencing the Lvit-IAG2 gene impeded ovarian development, including smaller previtellogenic oocytes, and lower expression of vitellogenin (Lvit-Vg) gene in hepatopancreas and vitellogenin receptor (Lvit-VgR) gene in the ovarian region. Notably, silencing the Lvit-IAG2 gene impeded individual growth of the species. Collectively, findings from this study demonstrate that Lvit-IAG2 and Lvit-IAG1 coordinatively function to modulate sexual differentiation in L. vittata; meanwhile, Lvit-IAG2 stimulates the growth of the PSH species.