Basal Oocytes Research Articles

Follicular metabolic alterations are associated with obesity in mares and can be mitigated by dietary supplementation

Obesity is a growing concern in human and equine populations, predisposing to metabolic pathologies and reproductive disturbances. Cellular lipid accumulation and mitochondrial dysfunction play an important role in the pathologic consequences of obesity, which may be mitigated by dietary interventions targeting these processes. We hypothesized that obesity in the mare promotes follicular lipid accumulation and altered mitochondrial function of oocytes and granulosa cells, potentially contributing to impaired fertility in this population. We also predicted that these effects could be mitigated by dietary supplementation with a combination of targeted nutrients to improve follicular cell metabolism. Twenty mares were grouped as: Normal Weight [NW, n = 6, body condition score (BCS) 5.7 ± 0.3], Obese (OB, n = 7, BCS 7.7 ± 0.2), and Obese Diet Supplemented (OBD, n = 7, BCS 7.7 ± 0.2), and fed specific feed regimens for ≥ 6 weeks before sampling. Granulosa cells, follicular fluid, and cumulus-oocyte complexes were collected from follicles ≥ 35 mm during estrus and after induction of maturation. Obesity promoted several mitochondrial metabolic disturbances in granulosa cells, reduced L-carnitine availability in the follicle, promoted lipid accumulation in cumulus cells and oocytes, and increased basal oocyte metabolism. Diet supplementation of a complex nutrient mixture mitigated most of the metabolic changes in the follicles of obese mares, resulting in parameters similar to NW mares. In conclusion, obesity disturbs the equine ovarian follicle by promoting lipid accumulation and altering mitochondrial function. These effects may be partially mitigated with targeted nutritional intervention, thereby potentially improving fertility outcomes in the obese female.

Does Platelet-Rich Plasma Treatment Increase In Vitro Fertilization (IVF) Success in the Infertile Population?

Platelet-rich plasma (PRP) is obtained by centrifuging the platelet-rich portion of the patient's own blood. The objective of our study is to retrospectively examine the impact of intraovarian PRP injection on infertile women with diminished ovarian reserve, specifically focusing on the oocyte count, oocyte quality, and endometrial thinning. A retrospective assessment was conducted on cases who had intraovarian PRP injection at the in vitro fertilization (IVF) unit of the Obstetrics and Gynecology Department of Gazi University School of Medicine hospital. The review encompasses the period from 1 January 2015 to 30 June 2020. The endometrial thickness, follicle count of greater than 14 millimeters, estradiol levels, follicle-stimulating hormone (FSH) levels, and antral follicle count were assessed during the menstrual cycle both prior to and within a period of 1-6 months following the PRP procedure. Twenty nonpregnant patients who had IVF before and 4-6 months after PRP were admitted to the post-PRP IVF cycle. The quantification of oocytes and M2 oocytes was conducted both prior to and subsequent to PRP treatment. Among 120 cases, only 60 cases who fulfilled inclusion criteria were analyzed.The basal endometrial thickness, basal follicle number (>14 mm), estradiol value, oocyte count, and M2 oocyte count exhibited a statistically significant increase following the administration of PRP injection (p<0.001). The basal FSH value exhibited a notable drop following the administration of PRP injection, with a statistically significant difference(p=0.002). In the pregnant group, the number of oocytes obtained with oocyte pick-up (OPU) increased by 300%, and in the nonpregnant group, the increase was 125% only. The number of M2 oocytes obtained with OPU increased by 250% in the pregnant group, while it was 93% in the nonpregnant group. Ultimately, the affordability of PRP production and its considerable theoretical efficacy have the potential to substantially decrease the expenses associated with assisted reproductive technology procedures. In the present scenario, the administration of an intraovarian PRP injection may be contemplated as a therapeutic intervention for women exhibiting diminished ovarian reserve.

Morphological and Morphometric Parameters of the Reproductive Organs of Euschistus heros (Hemiptera: Pentatomidae) Treated With a Sublethal Juvenile Hormone Analog

The stinkbug Euschistus heros is an important pest of Brazilian agricultural production with increasing importance in the Neotropical region. High reproductive potential and increased risk of resistance to insecticides are determining factors influencing its pest status. This work evaluated the effects of pyriproxyfen on the reproduction and morphological development of the reproductive system of E. heros. Pyriproxyfen was utilized at sublethal concentrations (LC30) in fourth-instar nymphs (N4). Sublethal pyriproxyfen resulted in a reduction in fertility and fecundity of 2 and 12% when only the males were treated, 47 and 53% when only the females were treated, and 32 and 46% when females and males were treated. Basal oocytes were larger and more previtellogenic in newly emerged pyriproxyfen-treated females. The nuclear area of testicular accessory cells shrunk after 10 and 15 days of age in treated insects. Similarly, testicular shape was altered, changing from an ellipsoid to an obpyriform pattern, characterized by hypertrophy of the basal region over time. The apparent area of the organ grew until ten days of age, then shrunk at 15 days of age. In summary, pyriproxyfen treatments disrupted the normal development of N4 of E. heros and diminished the reproductive potential of female and male adults.

Effect of Genetic Variants of Gonadotropins and Their Receptors on Ovarian Stimulation Outcomes: A Delphi Consensus.

BackgroundA Delphi consensus was conducted to evaluate the influence of single nucleotide polymorphisms (SNPs) in genes encoding gonadotropin and gonadotropin receptors on clinical ovarian stimulation outcomes following assisted reproductive technology (ART) treatment.MethodsNine experts plus two Scientific Coordinators discussed and amended statements plus supporting references proposed by the Scientific Coordinators. The statements were distributed via an online survey to 36 experts, who voted on their level of agreement or disagreement with each statement. Consensus was reached if the proportion of participants agreeing or disagreeing with a statement was >66%.ResultsEleven statements were developed, of which two statements were merged. Overall, eight statements achieved consensus and two statements did not achieve consensus. The statements reaching consensus are summarized here. (1) SNP in the follicle stimulating hormone receptor (FSHR), rs6166 (c.2039A>G, p.Asn680Ser) (N=5 statements): Ser/Ser carriers have higher basal FSH levels than Asn/Asn carriers. Ser/Ser carriers require higher amounts of gonadotropin during ovarian stimulation than Asn/Asn carriers. Ser/Ser carriers produce fewer oocytes during ovarian stimulation than Asn/Asn or Asn/Ser carriers. There is mixed evidence supporting an association between this variant and ovarian hyperstimulation syndrome. (2) SNP of FSHR, rs6165 (c.919G>A, p.Thr307Ala) (N=1 statement): Few studies suggest Thr/Thr carriers require a shorter duration of gonadotropin stimulation than Thr/Ala or Ala/Ala carriers. (3) SNP of FSHR, rs1394205 (−29G>A) (N=1 statement): Limited data in specific ethnic groups suggest that A/A allele carriers may require higher amounts of gonadotropin during ovarian stimulation and produce fewer oocytes than G/G carriers. (4) SNP of FSH β-chain (FSHB), rs10835638 (−211G>T) (N=1 statement): There is contradictory evidence supporting an association between this variant and basal FSH levels or oocyte number. (5) SNPs of luteinizing hormone β-chain (LHB) and LH/choriogonadotropin receptor (LHCGR) genes (N=1 statement): these may influence ovarian stimulation outcomes and could represent potential future targets for pharmacogenomic research in ART, although data are still very limited.ConclusionsThis Delphi consensus provides clinical perspectives from a diverse international group of experts. The consensus supports a link between some variants in gonadotropin/gonadotropin receptor genes and ovarian stimulation outcomes; however, further research is needed to clarify these findings.

P–628 Predicting oocyte yield in patients with diminished ovarian reserve using basal antral follicle count

Abstract Study question Is basal antral follicle count (bAFC) taken on day 1 to 3 of stimulation a useful predictor of oocyte yield in that cycle, in women with diminished ovarian reserve (DOR)? Summary answer Basal AFC has moderate correlation with final oocyte yield. A median 75% of the antral follicle count is collected as oocytes. What is known already The current theory of folliculogenesis suggests that all follicles available for recruitment are visible on ultrasound in the ovary at the point when ovarian stimulation is applied. This implies a tight correlation between the AFC on day 1–3 of a stimulation cycle (bAFC) and the eventual number of follicles collected. We hypothesise that in women with diminished ovarian reserve who receive maximum stimulation basal AFC would be a useful predictor of final oocyte yield in that cycle. Study design, size, duration This was a prospective single centre, observational study in a tertiary referral hospital in London. 125 women with DOR underwent controlled ovarian stimulation between December 2018 and January 2021. Participants/materials, setting, methods All study participants were given an antagonist cycle with a starting stimulation dose of 450iu and remained on the same dose throughout their treatment. We assessed the correlation between bAFC taken on day 1–3 of the stimulation cycle and the total number of oocytes collected. Main results and the role of chance A total of 150 treatment cycles were included in the analysis. The median age was 37 (IQR 35 – 39). The median AMH was 6.0 (IQR 4.4 – 8.9) and the median FSH was 7.6 (IQR 5.7 – 9.4). The median bAFC at the start was 9 (IQR 6 – 11). The median total stimulation dose was 4050iu (IQR 4050 – 4500). The median oestradiol on day of trigger was 5906 (IQR 4166 – 7397) and median number of oocytes collected was 7 (IQR 5 – 9). There was a moderate correlation between bAFC and the number of oocytes collected (r = 0.549, p = 0.005). The median ratio of oocytes collected over the number of antral follicles observed at the start was 72.7% (IQR 58.3 – 100). Limitations, reasons for caution We have standardised approach to AFC determination and have previously shown that AFC inter and intra-observer variability in our unit is low. Nevertheless, our study involved multiple operators for AFC determination which may introduce variability. Further variability may have been introduced at egg collection by varying technique. Wider implications of the findings: Studies of antagonist protocol in good prognosis patients suggest poor correlation between basal AFC and oocyte yield. In contrast, our study shows that in a population of women with DOR basal AFC provides useful information which can be used to counsel women around the expected oocyte yield of their cycle. Trial registration number Not applicable

Evaluation of the pesticide Oberon on a model organism Drosophila melanogaster via topical toxicity test on biochemical and reproductive parameters

Spiromesifen (Oberon® 240 SC), a pesticide widely used to control pests like mites and whiteflies, was investigated using Drosophila melanogaster Meigen, 1830 (Diptera, Drosophilidae) as a model organism. The compound was applied topically at two concentrations (LC10: 21.45 and LC25: 39.53 μg active ingredient/pupa), on newly molted pupae and assessed on morphometric measurements of ovaries and the progeny of surviving adults. Results showed that spiromesifen inhibited the growth and development of ovaries, reducing at the highest dose (LC25) the number of oocytes, the volume of basal oocytes and ovarian weight. Biochemical analysis revealed that the tested compound reduced the ovarian levels of carbohydrates and glycogen during the sexual maturation. Moreover, fecundity, fertility and number of descendants from parents that survived to the treatment of pupae were significantly reduced. The sex ratio determined indicated a significant decrease in treated series and males seemed more sensitive to spiromesifen than females. Lastly, the compound was found to affect the sexual behavior.

Physiological and biochemical effects of Olea europaea leaf extracts from four phenological growth stages on the oogenesis of female locust Locusta migratoria

AbstractThe effects of olive leaf extract (OLE) are studied on several reproductive variables and the ovarian biochemical composition of Locusta migratoria (Orthoptera: Acrididae) adult females. The methanolic extracts are prepared from the leaves sampled during four phenological growth stages of olive tree: cluster formation (Cf), swelling inflorescence buds (Sib), full flowering (Ff) and endocarp hardening (Eh). When applied to adult females during the pre‐ovipositional phase, the treatment elicites a significant adverse effect on their reproductive potential. Indeed, OLE significantly reduces both fecundity and fertility and affects oocyte growth during the first gonadotrophic cycle, as indicated by measurements of ovarian weight, length of terminal oocytes and ovarian index. Furthermore, OLE is examined with respect to ovarian biochemical components. Biochemical analyses reveal a significant reduction of ovarian contents of proteins, lipids and carbohydrates, suggesting a disruption in the incorporation of the haemolymph metabolites in the oocytes and an interference of OLE with the vitellogenesis process. The antigonadotrophic effect is confirmed by a histological study of the ovaries, which clearly shows a delay in ovarian development and in yolk accumulation in the basal oocytes of treated females. The most effect is noted with the extract prepared from the leaves collected at the swelling inflorescence buds for all measured parameters, which appears to be related to its high content of polyphenols.

Azadirachtin effects on mating success, gametic abnormalities and progeny survival in Drosophila melanogaster (Diptera).

Azadirachtin is a prominent natural pesticide and represents an alternative to conventional insecticides. It has been successfully used against insect pests. However, its effects on reproduction require further analysis. Here we investigated lethal and sublethal effects of azadirachtin, on treated adults in a model insect, Drosophila melanogaster (Meigen). Dose-mortality relationships as well as several parameters of reproduction (mating, spermatogenesis, oogenesis and fertility) were examined. Neem-Azal, a commercial formulation of azadirachtin, applied topically on newly emerged adults, increased mortality with a positive dose-dependent relationship. The LD50 (0.63 μg) was determined 24 h after treatment using a non-linear regression. Adults surviving this dose had a mating success that was divided by 3 and a progeny production reduced by half when males were treated, and even more when females were treated. When combining probability of survival, of mating and reduced progeny, it appeared that LD50 induced a 98% reduction in reproductive rates. Reduced progeny was partially explained by the effect of adult treatment on gametes number and abnormalities. The number of cysts and the apical nuclei positions within the cysts decreased by 29.7% and 20%, respectively, in males. In females, the number of oocytes per ovary and the volume of basal oocytes also decreased by 16.1% and 32.4%, respectively. Azadirachtin causes significant toxic effects in both sexes and decreases the fecundity and fertility of D. melanogaster. Females are more sensitive to azadirachtin. © 2017 Society of Chemical Industry.

Screening and identification of potential biomarkers in triple-negative breast cancer by integrated analysis.

Triple-negative breast cancer (TNBC) has attracted great attention due to its unique biology, poor prognosis, and aggressiveness. TNBC patients are more likely to suffer from metastasis. We screened and identified the TNBC-specific genes as potential biomarkers. A total of 167 breast cancer samples (45TNBC and 122non-TNBC) were used in the integrated analysis. Gene expression microarrays were used to screen the differentially expressed genes. We identified 65core DEGs. According to the GO and KEGG analysis, the gene function enrichment in TNBC was revealed, such as basal cell carcinoma, prostate cancer, oocyte meiosis and choline metabolism in cancer pathways. Moreover, the PPI network reconstruction would benefit the screening of hubs. A RFS analysis of TNBC-specific genes was also conducted. RT-PCR was used to validate the expression pattern of hubs in TNBC. Finally, nine genes were identified and all of them were novel, specific and higher dysregulation expressed genes in TNBC. Such that, these genes will serve as potential biomarkers in TNBC and benefit further research in TNBC.

Anatomical Description of the Reproductive System and Maturation States in Females of Omorgus suberosus (Fabricius) (Coleoptera: Trogidae)

Abstract The female reproductive system of Omorgus suberosus (Fabricius) is described and reproductive states identified and characterized based on the length of the basal oocytes. Using regression tree analysis, three groups were identified: immature females (≤1.29 mm), maturing females (1.30–2.06 mm), and mature females (≥2.07 mm), and differences in basal oocyte length were found among states of maturity. This study provides basic information for future studies on the ecology and reproductive behavior of O. suberosus, useful to understand the population dynamics of this species.

A potential insect growth regulator forcockroach control: design, synthesis andbioactivity of N-terminal-modified allatostatin analogues.

The FGLa-allatostatins (ASTs) are a family of neuropeptides that can inhibit juvenile hormone biosynthesis by the corpora allata (CA) in vitro, and therefore they are regarded as insect growth regulator (IGR) candidates for pest control. In our previous studies, an AST mimic, H17, was found to have a significant effect on JH biosynthesis by cockroach CA, both invitro and in vivo. To discover new potential mimics and explore the substituent effect on the inhibition of JH biosynthesis, 30 analogues, modified with various substituents on the benzene ring at the N-terminus of lead compound H17, were designed and synthesised. Their bioactivity in inhibiting JH biosynthesis by the CA of Diploptera punctata and the potency of M9, M10 and M11 in activation of Dippu-AstR were evaluated. All the analogues showed an effect on JH biosynthesis by CA in vitro. M9, M10 and M11 can activate the Dippu-AstR, albeit with much lower potency than that of AST 1. M11 also exhibited improved in vitro activity (IC50 6.98 nm) in comparison with the lead compound H17 (IC50 29.5 nm). In particular, M11 displayed good in vivo activity in inhibiting JH biosynthesis and basal oocyte growth. The structure-activity relationship studies suggest that different positions of substituents on the benzene ring of the cinnamic acid can lead to different activities. The para-substitution on the benzene ring plays an important role in inhibiting JH biosynthesis in vitro. Moreover, M11 is considered to be a potential IGR for cockroach control. © 2016 Society of Chemical Industry.

Adult pollen diet essential for egg maturation by a solitary Osmia bee

Reproduction is a nutritionally costly activity for many insects, as their eggs are rich in lipids and proteins. That cost seems especially acute for non-social bees, which for their size, lay enormous eggs. All adult female bees visit flowers, most of them to collect pollen and nectar, or sometimes oils, to feed their progeny. For adult bees, the need for pollen feeding has only been detailed for the honey bee, Apis mellifera. To experimentally test for the reproductive value of adult pollen feeding by a non-social bee, Osmia californica (Hymenoptera: Apiformes: Megachilidae), young female bees plus males were released into large glasshouse cages provided with either a male-fertile sunflower cultivar or a pollen-less one. Females regularly visited and drank nectar from flowers of both cultivars. Abundant orange pollen was seen regularly in guts of females confined with the male-fertile sunflowers, indicative of active pollen ingestion. All females’ terminal oocytes (next egg to be laid) were small at emergence. Oocytes of females confined with the pollen-less sunflowers remained small, despite frequent nectaring and exposure to other floral stimuli. In contrast, the basal oocytes of female O. californica with access to pollen had swelled to full size within ten days following emergence, enabling them to lay eggs in provided nest tubes. Adult females of this solitary bee required dietary pollen to reproduce; nitrogen stores acquired as larvae were inadequate. Early and regular pollen feeding in part paces the onset and maximum tempo of solitary bees’ lifetime reproductive output.

S6 protein kinase activates Juvenile Hormone and vitellogenin production in the cockroach Blattella germanica

AbstractNutritional status regulates different processes, such as growth and development, through TOR (target of rapamycin) and insulin receptor signalling pathways. The ribosomal S6 protein kinase (S6K) is a downstream element of both pathways. Using cDNA from the German cockroach Blattella germanica (L.), two S6K isoform sequences (BgS6K) are cloned. The long isoform differs from the short one by the insertion of a 22‐amino acid duplication, involving the key phosphorylation position Thr390. As a result of this, the long isoform presents a new, potentially regulatory phosphorylation site. RNA interference knockdown of both BgS6K isoforms induces an increase in the length of the last nymphal instar, together with a reduction in the mRNA levels of a number of enzymes of the Juvenile Hormone biosynthetic pathway in the corpora allata, vitellogenin mRNA levels in the fat body and basal oocyte length. Thus, BgS6K is important for nymphal development and is necessary for the full induction of Juvenile Hormone synthesis and vitellogenin production in adult females.

Sequential oogenesis is controlled by an oviduct factor in the locusts Locusta migratoria and Schistocerca gregaria: Overcoming the doctrine that patency in follicle cells is induced by juvenile hormone

In insects that lay eggs in large clutches, yolk accumulation in each of the many ovarioles is restricted to the basal (terminal) oocyte, the one closest to the lateral oviduct. All succeeding (subterminal) oocytes remain small until the terminal oocytes finished their development and were ovulated into the oviduct. The major step regulating yolk uptake by terminal oocytes is the formation of gaps between cells of the follicle layer, a process termed patency. In the migratory as well as in the desert locust, patency is induced by a Patency Inducing Factor (PIF) produced by the lateral oviducts. PIF is secreted in all regions of the lateral oviducts and interacts with the basal follicle cells via the pedicel, a fine duct that connects an ovariole with the oviduct. By this mechanism, patency is triggered in the follicle cells of the terminal oocyte only, restricting yolk accumulation to the oocytes next to ovulation. In contrast to the previous hypothesis, juvenile hormone (JH) is not necessary to induce patency, rather JH amplifies the effect of PIF.

Synthesis, bioactivity and functional evaluation of linker-modified allatostatin analogs as potential insect growth regulators

Abstract Insect growth regulators play an important role in integrated pest management strategies. The FGLa–allatostatins (ASTs) are a family of neuropeptides that can inhibit juvenile hormone (JH) biosynthesis by the corpora allata (CA) of Diploptera punctata in vitro, are regarded as insect growth regulator candidates. In the search for new potential mimics and to explore the effect of linker length on inhibiting JH biosynthesis, a series of AST analogs were synthesized by modifying the linker of K24, which was found to have a significant effect on JH biosynthesis in vitro in our previous study. Functional evaluation demonstrated that all the target compounds can activate the Dippu-AstR, albeit with different potencies. Analog L6 with the longest linker (n = 5), exhibited not only a promising effect on inhibition of JH biosynthesis both in vitro and in vivo, but also good activity in inhibiting basal oocyte growth. Structure–activity relationships (SAR) studies showed that longer linkers provided greater contribution to activity.

Effects of foraging distance on macronutrient balancing and performance in the German cockroach Blattella germanica.

The German cockroach (Blattella germanica) is an excellent model omnivore for studying the effect of foraging effort on nutrient balancing behavior and physiology, and its consequences for performance. We investigated the effect of foraging distance on individual German cockroaches by providing two foods differing in protein-to-carbohydrate ratio at opposite ends of long containers or adjacent to each other in short containers. Each food was nutritionally imbalanced, but the two foods were nutritionally complementary, allowing optimal foraging by selective feeding from both foods. We measured nutrient-specific consumption in fifth instar nymphs and newly eclosed females foraging at the two distances, hypothesizing that individuals foraging over longer distance would select more carbohydrate-biased diets to compensate for the energetic cost of locomotion. We then determined dry mass growth and lipid accumulation in the nymphs as well as mass gain and the length of basal oocytes in the adult females as an estimate of sexual maturation. Nymphs foraging over longer distance accumulated less lipid relative to total dry mass growth, but contrary to our predictions, their protein intake was higher and they accumulated more structural mass. In concordance, adult females foraging over longer distance gained more body mass and matured their oocytes faster. Our results show a positive effect of foraging distance on fitness-related parameters at two life stages, in both cases involving increased consumption of specific nutrients corresponding to requirements at the respective life stage.

Optimal cutoff value of basal anti-mullerian hormone in iranian infertile women for prediction of ovarian hyper-stimulation syndrome and poor response to stimulation

AimWe intended to establish the threshold of Anti-Mullerian Hormone (AMH) for detection of Ovarian Hyper-Stimulation Syndrome (OHSS) and poor response to treatment in Iranian infertile women.MethodsPre-stimulation menstrual cycle day-3 hormonal indices including basal AMH values were measured in 105 infertile women aged 32.5 ± 4.3 years. Patients underwent long GnRH agonist Controlled Ovarian Hyperstimulation (COH) in a referral infertility center (Tehran, Iran). The gonadotropin dose was determined based on the age and basal serum Follicular Stimulating Hormone (FSH) level. The IVF/ICSI cycles were followed and the clinical and sonographic data were recorded.ResultsSixteen cases developed OHSS. The prevalence of PCOS was higher in subjects with OHSS [62.5 % (38.8-86.2) vs. 17 % (9.2-24.9)]. The patients with OHSS had higher ovarian follicular count [23.7 (3.2) vs. 9.1 (0.5); p < 0.05], collected oocytes [13.5 (1.9) vs. 6.9 (0.5); p < 0.05] and AMH level [7.9 (0.7) vs. 3.6 (0.3); p < 0.05]. Basal AMH level and oocyte yields (but not age, BMI, and PCOS) correlated with occurrence of OHSS; and only the AMH levels were associated with poor ovarian response (oocytes yield ≤ 4). The optimal cutoff value for the prediction of OHSS was 6.95 ng/ml (area under the receiver operating characteristics curve: 0.86; CI: 0.78-0.95; sensitivity: 75 %; specificity: 84 %; odds ratio for occurrence of OHSS: 9 and p < 0.001). The optimal cut point to discriminate poor response (oocytes ≤4) was 1.65 ng/ml ( AUC : 0.8; CI: 0.69-0.91; sensitivity: 89 % specificity : 71 %; and OR = 23.8 and P value <0.001).ConclusionsIranian women with basal AMH level > 6.95 ng/ml are at high risk of developing OHSS and those with AMH level < 1.65 ng/ml are poor responders.

Suboptimal nutrient balancing despite dietary choice in glucose-averse German cockroaches, Blattella germanica

Insects have evolved fine-tuned gustatory and post-ingestive physiological mechanisms that enable them to self-select an optimal composition of macronutrients. Their ability to forage optimally among multiple food sources and maximize fitness parameters depends on their ability not only to taste and perceive the nutritional value of potential foods but also to avoid deleterious components; the strength of such avoidance should reflect the severity of the perceived hazard. In German cockroaches (Blattella germanica), glucose aversion has evolved in some populations in response to anthropogenic selection with glucose-containing insecticidal baits. In four feeding treatments, we gave newly eclosed glucose-averse female cockroaches free choice to feed from two artificial, nutritionally complementary foods varying in protein and carbohydrate composition, with glucose or fructose as the sole carbohydrate source in either food. After 6days of feeding, we measured diet consumption and the length of basal oocytes as an estimate of sexual maturation. The females did not compromise on their aversion to glucose in order to balance their protein and carbohydrate intake, and experienced lower sexual maturation rates as a consequence. Nutrient specific hunger via feedback mechanisms, and adjustments to gustatory sensitivity thus do not override the deterrence of glucose, likely due to strong selection against ingesting even small amounts of toxin associated with glucose in baits. In the absence of baits, glucose aversion would be expected to incur a fitness cost compared to wild-type individuals due to lower overall food availability but also to larger difficulty in attaining a nutritionally balanced diet.

Adaptive contraction of diet breadth affects sexual maturation and specific nutrient consumption in an extreme generalist omnivore.

Animals balance their intake of specific nutrients, but little is known about how they do so when foraging in an environment with toxic resources and whether toxic foods promote adaptations that affect life history traits. In German cockroach (Blattella germanica) populations, glucose aversion has evolved in response to glucose-containing insecticidal baits. We restricted newly eclosed glucose-averse (GA) and wild-type (WT) female cockroaches to nutritionally defined diets varying in protein-to-carbohydrate (P:C) ratio (3:1, 1:1, or 1:3) or gave them free choice of the 3:1 and 1:3 diets, with either glucose or fructose as the sole carbohydrate source. We measured consumption of each diet over 6days and then dissected the females to measure the length of basal oocytes in their ovaries. Our results showed significantly lower consumption by GA compared to WT cockroaches when restricted to glucose-containing diets, but also lower fructose intake by GA compared to WT cockroaches when restricted to high fructose diets or given choice of fructose-containing diets. Protein intake was regulated tightly regardless of carbohydrate intake, except by GA cockroaches restricted to glucose-containing diets. Oocyte growth was completely suppressed in GA females restricted to glucose-containing diets, but also significantly slower in GA than in WT females restricted to fructose-containing diets. Our findings suggest that GA cockroaches have adapted to reduced diet breadth through endocrine adjustments which reduce requirements for energetic fuels. Our study illustrates how an evolutionary change in the chemosensory system may affect the evolution of other traits that govern animal life histories.

Identification and characterization of the NMDA receptor and its role in regulating reproduction in the cockroach Diploptera punctata.

The NMDA receptor (NMDAR) plays important roles in excitatory neurotransmission and in the regulation of reproduction in mammals. NMDAR in insects comprises two subunits, NR1 and NR2. In this study, we identified two NR1 paralogs and eleven NR2 alternatively spliced variants in the cockroach Diploptera punctata. This is the first report of NR1 paralogs in insects. The tissue distributions and expression profiles of DpNR1A, DpNR1B and DpNR2 in different tissues were also investigated. Previous studies have demonstrated NMDA-stimulated biosynthesis of juvenile hormone (JH) in the corpora allata through the influx of extracellular Ca(2+) in Diploptera punctata. However, our data show that the transcript levels of DpNR1A, DpNR1B and DpNR2 were low in the corpora allata. MK-801, a high-affinity antagonist of NMDAR, did not show any effect on JH biosynthesis in vitro. In addition, neither partial knockdown of DpNR2 nor in vivo treatment with a physiologically relevant dose of MK-801 resulted in any significant change in JH biosynthesis or basal oocyte growth. Injection of animals with a high dose of MK-801 (30 µg per animal per injection), which paralyzed the animals for 4-5 h, resulted in a significant decrease in JH biosynthesis on days 4 and 5. However, the reproductive events during the first gonadotrophic cycle in female D. punctata were unaffected. Thus, NMDAR does not appear to play important roles in the regulation of JH biosynthesis or mediate reproduction of female D. punctata.