Biomedical subjects

A J Conley

Publications and source records attributed to A J Conley.

At least 37 records · Page 2Linked to original sources

PubMed2001

Endocrine relationships of Meishan and White composite females after weaning and during the luteal phase of the estrous cycle.

Endocrine differences between European crossbred and Chinese Meishan females have been somewhat modest. Indwelling jugular cannulas were placed in Meishan (n = 7) and White composite (n = 6) multiparous sows before weaning, and blood was sampled from 4 h before to 240 h after removal of litters. Temporal changes in FSH, triiodothyronine (T3), and tetraiodothyronine (T4) after weaning differed between Meishan and White composite sows. Plasma cortisol concentrations were higher in Meishan sows than in White composite sows (P < 0.01), but there were no temporal differences between breeds after weaning. Other hormones monitored (prolactin, GH, IGF-I, and inhibin) were not different between breeds. In the second experiment, Meishan gilts (n = 7) and sows (n = 7) and White composite sows (n = 9) were cannulated during the luteal phase of the estrous cycle and sampled after treatments consisting of GnRH (15 and 150 ng/kg BW), ovariectomy, estradiol cypionate challenge after ovariectomy (10 microg/kg BW), and GnRH antagonist. In response to GnRH challenge, White composite sows had elevated (P < 0.05) concentrations of gonadotropins compared with Meishan. Cortisol concentrations were elevated in Meishan as compared with White composite females (P < 0.01) but unaffected by GnRH treatment. After ovariectomy, LH concentrations increased 3 h sooner in White composite than in Meishan females. After GnRH antagonist, declines in gonadotropins were comparable in both breeds, but LH increased in Meishan females by 20 h but not until after 54 h in White composite females. White composite females demonstrated only a short decline in FSH in response to the GnRH antagonist, but Meishan females had a prolonged decline in FSH concentrations. Consistently elevated cortisol concentrations in Meishan females may positively impact ovarian function; thus, the assumption that high plasma cortisol concentration as an index of stress that impairs reproductive function should be reevaluated in swine. There were few endocrine differences that would relate to or explain increased ovulation rates found in the Meishan breed; thus, other mechanisms must exist to explain the increase in ovarian function in the Meishan breed.

Animals↗

PubMed2001

Influence of epidermal growth factor on mammalian oocyte maturation via tyrosine-kinase pathway.

Epidermal growth factor (EGF) has been reported to promote different functions in mammalian ovaries, including oocyte maturation. The aim of the present study was to establish: that EGF influences oocyte maturation in ovine and equine, that a tyrosine kinase-dependent intracellular mechanism mediates EGF effect and, that EGF-R receptor is detectable in ovarian follicles by immunohistochemistry methods. Selected ovine and equine oocytes were aspirated from 2-5 mm (ovine) or 25 mm (equine) follicles and cultured in TCM 199 for 22 (ovine) or 36 hours (equine). They are then subjected to culture with EGF and two specific tyrosine-kinase inhibitors (TKIs, tyrphostins A-23 y A-47). Maturation was determined as the percentage of oocytes at metaphase II stage after culture. Treatments with EGF significantly increased incidences of metaphase II stage compared to controls (86.2% vs. 55% and 70.4% vs. 22.5% in ovine and equine oocytes, respectively). Tyrphostins A-23 and A-47 were effective in suppressing EGF-effect on oocytes. EGF-receptor was localized in follicles, being more prominent in cumulus and granulosa cells. These results confirm that EGF has a physiological role in the regulation of oocyte maturation via tyrosine-kinase pathway.

Animals↗

PubMed2001

Influence of epidermal growth factor on mammalian oocyte maturation via tyrosine-kinase pathway.

Animals↗

PubMed2000

Bluetongue and equine viral arteritis viruses as models of virus-induced fetal injury and abortion.

A number of viruses have the capacity to cross the placenta and infect the fetus to cause, among other potential outcomes, developmental defects (teratogenesis), fetal death and abortion. Bluetongue virus (BTV) infection of fetal ruminants provides an excellent model for the study of virus-induced teratogenesis. This model has shown that only viruses modified by passage in cell culture, such as modified live virus vaccine strains, readily cross the ruminant placenta, and that the timing of fetal infection determines the outcome. Thus, cerebral malformations only occur after fetal infection at critical stages during development and the precise timing of fetal BTV infection determines the severity of the malformation present at birth. Fetal BTV infection also can result in fetal death, followed by abortion or resorption, growth retardation, or no obvious abnormalities, depending on age of the conceptus at infection. Equine arteritis virus (EAV) infection of the equine fetus causes fetal death and abortion but not teratogenesis. These two fetal viral infections are useful not only for the study of teratogenesis and fetal disease, but also to further characterize and compare the complex process that is responsible for normal induction of parturition in ruminants and horses.

Abortion, Veterinary↗

PubMed2000

2,3,7,8-tetrachlorodibenzo-p-dioxin decreases estradiol production without altering the enzyme activity of cytochrome P450 aromatase of human luteinized granulosa cells in vitro.

This study was designed to examine the in vitro effects of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) on steroid production in human luteinizing granulosa cells (hLGC). TCDD (10 nM) or its solvent was added at the time of changing medium, directly to the cells, every 48 h for 8 days. To test the hypothesis that TCDD reduces estradiol (E(2)) synthesis by an effect on cytochrome P450 aromatase, aromatase protein and aromatase activity were evaluated. E(2) decreased without changing either aromatase protein or its enzyme activity, suggesting that the target of toxicity of TCDD is upstream of aromatase in the steroidogenic pathway. When hLGC were incubated in the presence of labeled E(2), no changes in the metabolism of E(2) by treatment were observed. Since TCDD did not change progesterone or 17alpha-hydroxyprogesterone, the inhibition of E(2) synthesis by TCDD would seem not to involve steps such as cholesterol transport. Furthermore, the TCDD effect on E(2) concentration in these cells disappeared in the presence of excess androgens. We conclude that the inhibition of E(2) secretion by TCDD involves intermediate steps, specifically, the provision of androgens for aromatization.

17-alpha-Hydroxyprogesterone↗

PubMed2000

Tissue-specific localization of cytochrome P450 aromatase in the equine embryo by in situ hybridization and immunocytochemistry.

Estrogen production by the preimplantation equine embryo is presumed to be important in maternal-conceptus communication in the mare. The synthesis of C(18) estrogens from C(19) androgens requires cytochrome P450 aromatase (P450(arom)) in the conceptus, but little information is available on the specific tissue location or potential developmental patterns of expression for the horse. The goal of this research was to localize P450(arom) in the equine conceptus by immunocytochemistry and in situ hybridization. Intact blastocyst-stage embryos were collected by nonsurgical flush on Days 12-15 of pregnancy, fixed in 4% paraformaldehyde, and paraffin-embedded. Aromatase protein was localized using rabbit anti-human placental aromatase antiserum with a detection system utilizing peroxidase and 3-amino-9-ethylcarbazole. For in situ hybridization, tissue sections were incubated with sense or antisense [(35)S]UTP-labeled cRNA probes prepared from equine aromatase cDNA. Aromatase protein and transcript were abundant in the extraembryonic trophectoderm but absent from embryonic ectoderm. No P450(arom) expression was detected in abembryonic endoderm or mesoderm. Aromatase expression was demonstrated in the endoderm beneath the disc (hypoblast). This pattern of P450(arom) expression in the equine blastocyst closely resembles that seen transiently in the porcine embryo, suggesting that regulatory mechanisms conferring tissue specificity may be conserved.

Animals↗

PubMed2000

The localization of DHEA sulfotransferase in steroidogenic and steroid metabolizing tissues of the adult rhesus macaque monkey.

Dehydroepiandrosterone sulfate is a major secretory product of the human adrenal cortex during intrauterine development as well as during adulthood. There are few animal experimental models that share this characteristic pattern of adrenal cortical steroidogenesis, which probably accounts for the relative paucity of information about the control of development and function of the adrenal androgen secretory apparatus. Adrenal androgen production in the rhesus macaque shares many similarities with that of the human. We sought to determine the tissue distribution of the enzyme DHEA sulfotransferase (DST) in the rhesus. Tissues were harvested at the time of autopsy from 7 adult monkeys (5 M, 2 F) ranging from 8-15 yrs old, and were fixed in 4% paraformaldehyde, embedded in paraffin, and sectioned at 5 mu thickness. Tissue sections were immunostained for DST with an anti-human liver DST antibody. DST was not detected in the testis or ovary. In the liver, immunoreactive DST was detected only in hepatocytes and in the kidney, DST was found only in the epithelial cells lining the collecting tubules. In the adrenal, DST was present in the cells of the zona reticularis but was not found in the cells of the medulla, zona fasciculata or in the very prominent zona glomerulosa. DST was most prominent in cells that were closest to the reticularis-medullary border. In most adrenals evaluated, the immunopositive cells were scattered, rather than forming a continuous band of cells around the medulla. The tissue distribution of DST in the adult rhesus macaque is qualitatively similar that observed in the adult human. These data aresuggestive that the rhesus might be an excellent model for the exploration of factors that regulate adrenal androgen production during development, aging, and in response to illness and stress, all of which have been found to be associated with variations in DHEA and DHEA sulfate production in the human.

Adrenal Glands↗

PubMed1999

Studies on the origin of ovarian interstitial tissue and the incidence of endometrial hyperplasia in domestic and feral cats.

Ovarian interstitial cells (OICs) are a common feature of mammalian gonads but little is understood concerning their origin or functional significance. This study investigated the development and steroidogenic potential of OIC in feral and colony-reared feline queens. Reproductive tracts, collected from a total of 50 female colony and feral cats, were fixed and analyzed by morphometry. Ovarian sections were also immuno-stained for the expression of the steroidogenic enzymes 17alpha-hydroxylase/17,20 lyase cytochrome P450 (P450c17), 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase (3beta-HSD), and aromatase. These findings were related to serum estradiol and testosterone concentrations and to the degree of existing cystic endometrial hyperplasia (CEH). Feral cats had three times as many OICs as colony-reared queens (2713 +/- 855 vs 744 +/- 494 cells/mm(2), P < 0.01). These cells were lipid laden and expressed both P450c17 and 3beta-HSD at levels that were higher than those seen in the theca interna of adjacent follicles. Aromatase expression was undetectable. The pattern of enzyme expression was consistent with development of interstitial tissue from atretic follicles and the potential for continued steroid secretion during the anestrum. The incidence of CEH was higher in older (>5 years old; 88.2%) than in younger (2-4 years; 30%) colony queens (P < 0. 01), whereas no such disease was evident in any of the feral cats. Estradiol levels were higher in colony-reared than in feral cats, but testosterone levels were not different. These data are consistent with the transformation of the theca interna of atretic follicles in cats into OICs that retain a similar, or even enhanced, steroidogenic phenotype. Colony-reared cats exhibit a predisposition to CEH compared with feral queens that is associated with elevated serum estradiol concentrations. Whether or not OICs somehow prevent the development of uterine disease or otherwise reflect a gonadal response to reduced negative feedback on the hypothalamic-pituitary axis remains to be determined.

3-Hydroxysteroid Dehydrogenases↗

PubMed1999

Development and differentiation of the interstitial and tubular compartments of fetal porcine testes.

Male differentiation is initiated by fetal testicular androgen synthesis, catalyzed by the enzyme 17alpha-hydroxylase/17,20 lyase cytochrome P450 (P450c17). This study was an investigation of testicular development and differentiation in porcine fetuses recovered on Days 30-42 of gestation. The expression of P450c17 was localized in fetal gonads by in situ hybridization and immunocytochemistry and related to cellular proliferation through expression of the proliferating cell nuclear antigen (PCNA). Gonadal P450c17 expression was quantified by Western immunoblot analysis and related to testosterone secretion by cultured explants of fetal gonads. P450c17 transcripts were detected in the interstitium surrounding testicular cords preceding the appearance of the enzyme protein. The intensity of both P450c17 hybridization and staining was greater in Yorkshire fetal gonads, which also exhibited more advanced tubular development. PCNA staining was prominent within tubular primordia and was higher in testes from Yorkshire than from Meishan fetuses on all days examined. P450c17 expression paralleled testosterone secretion, which decreased by Day 42, and was generally less in cultures of Meishan than of Yorkshire fetal gonads. These data demonstrate that the expression of P450c17 in porcine fetal testes coincides with differentiation of central medullary cells and androgen secretion during gonadal development between Days 30 and 42 of gestation. This occurs as medullary cords organize and is associated with changes in cellular proliferation within the tubular compartment.

Animals↗

PubMed1999

Changes in testosterone metabolism associated with the evolution of placental and gonadal isozymes of porcine aromatase cytochrome P450.

Differences in the catalytic activity of the placental and gonadal isozymes of porcine aromatase cytochrome P450 (P450arom) were examined in cell lines exhibiting stable expression of recombinant enzyme. Cell lines were selected that expressed high, but similar, immunodetectable levels of each isozyme based on Western analysis. Aromatase activity varied with growth in culture, decreasing at confluence from a peak reached between 50-80% cell density. Cells expressing the placental isozyme had 3-5 times higher catalytic activity (per mg protein) than those expressing the gonadal isozyme. The P450arom inhibitor fadrazole (1 microM) inhibited more than 97% of this activity, whereas another imidazole, etomidate (1 microM), selectively inhibited gonadal P450arom activity by 92%. Estrogen synthesis from androstenedione and testosterone was determined by RIA and confirmed by HPLC analysis, which also identified the accumulation of the 19-hydroxy and 19-oxo intermediates of the respective substrates. There was no evidence of other steroid metabolites accumulating in the media of cell lines expressing either isozyme. Tritiated water formed during aromatization of substrates 3H labeled at the C1 and C2 positions was stereo-selective for the beta orientation, but less so for testosterone than androstenedione during metabolism by the porcine placental (and human) isozyme than the gonadal isozyme. Testosterone showed a higher affinity for the porcine placental P450arom than the gonadal P450arom, but both isozymes had similar affinities for androstenedione. Testosterone was also aromatized more slowly than androstenedione by the porcine gonadal P450arom. These data suggest that catalytic differences have arisen in the substrate binding pocket during the evolution of isozymes of porcine P450arom that affect androgen metabolism, particularly the aromatization of testosterone. The physiological significance of these differences to the reproductive biology of the pig remains to be determined.

Androstenedione↗

PubMed1999

Unique regulation of CYP17 expression in the trophectoderm of the preattachment porcine blastocyst.

Expression of the gene encoding cytochrome P450 17alpha-hydroxylase, CYP17, is necessary for adrenal and gonadal steroidogenesis in most species. However, some animals, such as the pig, express CYP17 in the trophectoderm of the preattachment blastocyst, an event associated with estrogen synthesis and the establishment of pregnancy. How trophoblastic expression of CYP17 is regulated in the porcine blastocyst remains unknown and forms the basis of the following studies. The porcine CYP17 gene, including the complete coding and several kilobases of 5'-flanking regions, was cloned and sequenced. Blastocysts were examined by Northern analysis to verify the level of CYP17 transcript, and tissue-specific expression in the trophectoderm was confirmed by in situ hybridization. Primer extension, S1 nuclease protection, and 5'-rapid amplification of cDNA ends confirmed a common proximal transcription start site in adrenals and gonads (-48 bp) but identified a unique distal start site used in porcine trophectoderm (-182 bp). Additionally, reporter analysis of the CYP17 regulatory region demonstrated that constructs (-27 to -718 bp) were unresponsive to forskolin when expressed in porcine trophoblast cells, suggesting that trophoblast may not be able to respond to cAMP induction of this gene. The identification of this distal, previously undescribed, transcriptional start site suggests that unique mechanisms control the expression of CYP17 in porcine trophectoderm and possibly other genes important in implantation and early placental development.

Adrenal Cortex↗

PubMed1998

Association of antibody reactivity to ELDKWA, a glycoprotein 41 neutralization epitope, with disease progression in children perinatally infected with HIV type 1.

The association between antibody reactivity to the neutralizing epitope ELDKWA in the transmembrane glycoprotein gp41 and disease progression was investigated in 29 children perinatally infected with HIV-1. Levels of antibody reactivity to this epitope, measured over time, were associated with absolute CD4+ lymphocyte numbers and disease status, and inversely associated with the levels of acid-dissociated p24 antigen in the plasma. Early virus isolates from 10 of 12 children with no detectable antibody reactivity to this epitope were sequenced. Only three contained sequences that differed from the consensus, indicating that this epitope is well conserved in this population. None of these three children developed antibodies to the autologous sequences, indicating that at least 80% of children with negative antibody reactivity to this epitope were true nonresponders. Together, these results indicate that the ELDKWA determinant could be an important component in the formulation of a vaccine or for immunotherapeutic approaches to HIV-1 infection.

Amino Acid Sequence↗

PubMed1998

Monitoring pregnancy in twinning pygmy loris (Nycticebus pygmaeus) using fecal estrogen metabolites.

Estrone and estrone conjugates were measured in the feces of three female pygmy lorises (Nycticebus pygmaeus) throughout estrus, pregnancy, and the postpartum period. Two females gave birth to twins, while the third had a single stillborn. A comparison between the hormonal profiles of these three pregnancies with each other and with previously reported pregnancies resulting in singletons or twins [Jurke et al., American Journal of Primatology 41:103-115, 1997] revealed a characteristic pattern of hormonal excretion. This report adds data to and confirms previous claims that monitoring estrone in this species provides a tool to assess gestation length (via determination of estrus period) and to predict the date of parturition and the number of offspring. However, there was an exceptional case of a pregnancy which had the hormonal appearance of a twin pregnancy but resulted in a single stillborn infant. This case prompted us to search for new insights into the characteristics and the origin of the estrogens that are excreted into the feces. Aromatase activity was evaluated in five partial placentae.

Animals↗

PubMed1998

Vaccine protection against a heterologous, non-syncytium-inducing, primary human immunodeficiency virus.

Vaccine-induced protection of chimpanzees against laboratory-adapted and syncytium-inducing, multiply passaged primary human immunodeficiency virus type 1 (HIV-1) isolates, but not against non-syncytium-inducing, minimally passaged ones, has been demonstrated. Following challenge with such an isolate, HIV-15016, we obtained complete protection in one of three chimpanzees previously protected against low- and high-dose HIV-1SF2 exposures after immunization with an adenovirus-HIV-1MN gp160 priming-HIV-1SF2 gp120 boosting regimen. At challenge, the protected chimpanzee exhibited broad humoral immunity, including neutralizing antibody activity. These results demonstrate the potential of this combination vaccine strategy and suggest that vaccine protection against an HIV isolate relevant to infection of people is feasible.

AIDS Vaccines↗

PubMed1997

Anti-human immunodeficiency virus type 1 human monoclonal antibodies that bind discontinuous epitopes in the viral glycoproteins can identify mimotopes from recombinant phage peptide display libraries.

A phage display library screening approach was used to identify peptide sequences that could bind to anti-HIV-1 MAbs whose binding specificities are complex. Most of the antibodies used recognize discontinuous epitopes in gp120 and one recognizes gp41. Both a 15-mer and a 21-mer display library (each with a complexity of greater than 60 x 10[6]) and two constrained, V3 region-biased libraries, all expressed as recombinant pIII protein of filamentous phage, were used. The unmapped anti-gp120 human MAb A32 recognized a set of related linear sequences and repeatedly identified a single phage sequence that could form a cyclic disulfide structure. Selection methods were also developed so that phage could be obtained by competition selection in the presence of antibody bound to native, monomeric gp120 antigen (used with MAb IgG1b12 and the anti-gp120 V3 region MAb 447-52D) or gp120 variable region 3 synthetic peptides (used with anti-gp120 V3 region MAb 19b). The potent, virus-neutralizing MAb IgG1b12 recognized numerous sequences and, when used in competition with gp120, recognized only one sequence. These studies extend the range of antibody determinant studies that can be performed with display phage libraries, demonstrate a workable experimental strategy for use of competition ligands to discriminate among phage mimotopes, and provide a large number of mimotopes that bind potent virus-neutralizing MAbs for HIV-1 vaccine studies.

Amino Acid Sequence↗

PubMed1997

Human monoclonal antibodies to the V3 loop of HIV-1 with intra- and interclade cross-reactivity.

Five human anti-V3 mAbs were generated from Ab-producing cells derived from the blood of HIV-1-infected individuals from North America and selected using the V3 peptide of a divergent clade B isolate, HIV(RF). The anti-V3(RF) mAbs were mapped to a cluster of three overlapping epitopes present in the KSITKGP sequence located in the hypervariable region on the N-terminal side of the V3 loop. Broad immunochemical cross-reactivity was noted when the mAbs were tested for binding to V3 peptides derived from four clade A viruses, nine clade B viruses, and two clade C viruses. These results demonstrate antigenic relatedness in the V3 regions of these three HIV-1 clades. Affinities determined by surface plasmon resonance were higher for recombinant gp120 than for V3 peptides, suggesting that these mAbs recognize both linear and conformationally dependent epitopes of the V3 loop. Two of the mAbs neutralized four clade B T cell line-adapted and primary isolates with varying degrees of potency. The two neutralizing mAbs were the most cross-reactive with V3 peptides from several clades, had the highest affinity for V3(RF) and V3(MN), and stained HIV-infected cells. The data suggest that cross-reactivity, affinity, cell surface staining, and neutralizing activity are characteristics that describe an optimal fit between Ag and Ab. The results also demonstrate that the V3 peptides representing the sequence of several clade A, B, and C viruses share antigenic features that are recognized by the human immune response, a finding that suggests that cross-clade immunity to HIV-1 may be inducible by HIV-1 vaccines.

Antibodies, Monoclonal↗

PubMed1997

Recombinant human monoclonal antibody IgG1b12 neutralizes diverse human immunodeficiency virus type 1 primary isolates.

The CD4-binding domain of human immunodeficiency virus type 1 (HIV-1) gp120 elicits antibodies that are present in infected human sera. Monoclonal antibodies that recognize the HIV-1 gp120 CD4-binding domain have been isolated. Some of these antibodies can neutralize laboratory-adapted strains of HIV-1 and probably mediate neutralization by interfering with virus binding to its cellular CD4 receptor. However, most anti-CD4 binding domain antibodies do not neutralize primary HIV-1 isolates. We used primary HIV-1 isolates in an infectivity reduction assay to test the uniquely derived anti-CD4 binding domain recombinant human monoclonal antibody, IgG1b12. All of the tested HIV-1 isolates were neutralized by this antibody. Additional studies indicated that neutralization of a primary isolate with MAb IgG1b12 did not require continuous exposure of human peripheral blood mononuclear cell cultures to the antibody. Finally, a complete IgG1 molecule of an in vitro-selected b12 FAb mutant with a > 400-fold increase in affinity was assembled, expressed in mammalian cells, and evaluated in the infectivity reduction assay in comparative studies with the parent IgG1b12 antibody. The mutant did not retain the level of primary isolate neutralization potency that was a property of the parent molecule. Thus, we confirm that recombinant IgG1b12 has a unique specificity, and that it can neutralize all primary isolates tested in human PBMC cultures in vitro.

Antibodies, Monoclonal↗

PubMed1997

Yolk steroids decline during sexual differentiation in the alligator.

The leading explanation of temperature-dependent sex determination (TSD) in reptiles postulates that (1) ovarian differentiation is directed by estrogen and that (2) estrogen is synthesized in the developing gonad following induction of aromatase expression. However, the source of steroid substrate for aromatization has not yet been identified. In addition, sex ratios vary as a function of clutch, but such biases are as yet unexplained. To address these issues, we measured estradiol, testosterone, and androstenedione in yolks of the American alligator (Alligator mississippiensis) before, during, and after the period of gonadal differentiation in this TSD species. Eggs were collected from a wild population in Louisiana and were incubated at male- and female-determining constant temperatures in the lab, as well as at intermediate temperatures that produced both sexes. Steroids were assayed in yolk extracts after celite column chromatography. All three steroids were found to be in the range of nanograms/gram of yolk at stage 16. Androstenedione was the predominant steroid, 2- to 3-fold higher in concentration than estradiol and 15- to 20-fold higher than testosterone. The levels of these steroids declined (5- to 30-fold) between stages 16 and 25, most markedly between stages 21 and 23, regardless of incubation temperature. The chronology of this sharp decline in steroid levels in our study coincides with the timing of gonadal differentiation in this species, between stages 21 to 23 based on previous reports. Estradiol levels in yolks differed by 3-fold in some clutches relative to others, whereas, no clutch differences were apparent for either androstenedione or testosterone. These data demonstrate that alligator yolk contains high concentrations of two steroid substrates utilized for estrogen synthesis, as well as significant quantities of estradiol itself. We hypothesize that estradiol levels in yolk provide a steroid background, variable among and within clutches, on which gonadal development is initiated and proceeds. As a consequence, we suggest that yolk provides an epigenetic maternal contribution that modulates the effect of incubation temperature on hatchling sex.

Alligators and Crocodiles↗