Insulin-like growth factor-I activates KiSS-1 gene expression in the brain of the prepubertal female rat

KiSS-1 gene expression has been shown to increase as puberty approaches, and its peptide products, kisspeptins, are involved in LHRH secretion at puberty. Factors contributing to increased KiSS-1 expression, however, have not been identified; thus, the purpose of this study was to assess whether IGF-I could induce transcription of this gene in prepubertal female rats. IGF-I or saline was centrally administered to immature rats that were killed 2, 4, and 6 h later. Real-time PCR revealed that IGF-I induced (P < 0.01) KiSS-1 gene expression at 6 h in a tissue fragment that contained both the anteroventral periventricular (AVPV) and arcuate (ARC) nuclei. Subsequently, the AVPV and ARC nuclei were separated to assess whether region-specific effects could be identified. IGF-I stimulated (P < 0.01) KiSS-1 gene expression in the AVPV nucleus at 6 h after injection, with no change observed in the ARC nucleus. Serum estradiol (E2) levels were not altered at any time point after IGF-I, demonstrating that the increased KiSS-1 expression observed was not caused by an elevation in E2. Additionally, the IGF-I action to induce KiSS-1 gene expression in the AVPV nucleus was further demonstrated when the IGF-I was administered systemically. E2 appears to play an important permissive role because 1-d ovariectomized rats responded to IGF-I with increased (P < 0.01) KiSS-1 expression, whereas, 20 d after ovariectomy, when the E2 levels had fallen below assay sensitivity, the IGF-I was unable to induce KiSS-1 expression. The IGF-I effect was further demonstrated by showing that the IGF-I receptor antagonist, JB-1, blocked the IGF-I-induced increase in KiSS-1 expression. Collectively, these data indicate that IGF-I is an activator of the KiSS-1 gene in the prepubertal female rat.

Determination of quantitative trait loci (QTL) for early maturation in rainbow trout (Oncorhynchus mykiss)

To identify quantitative trait loci (QTL) influencing early maturation (EM) in rainbow trout (Oncorhynchus mykiss), a genome scan was performed using 100 microsatellite loci across 29 linkage groups. Six inter-strain paternal half-sib families using three inter-strain F(1) brothers (approximately 50 progeny in each family) derived from two strains that differ in the propensity for EM were used in the study. Alleles derived from both parental sources were observed to contribute to the expression of EM in the progeny of the brothers. Four genome-wide significant QTL regions (i.e., RT-8, -17, -24, and -30) were observed. EM QTL detected on RT-8 and -24 demonstrated significant and suggestive QTL effects in both male and female progeny. Furthermore, within both male and female full-sib groupings, QTL on RT-8 and -24 were detected in two or more of the five parents used. Significant genome-wide and several strong chromosome-wide QTL for EM localized to different regions in males and females, suggesting some sex-specific control. Namely, QTL detected on RT-13, -15, -21, and -30 were associated with EM only in females, and those on RT-3, -17, and -19 were associated with EM only in males. Within the QTL regions identified, a comparison of syntenic EST markers from the rainbow trout linkage map with the zebrafish (Danio rerio) genome identified several putative candidate genes that may influence EM.

Gonadotrophin-inhibitory hormone receptor expression in the chicken pituitary gland: potential influence of sexual maturation and ovarian steroids

Gonadotrophin-inhibitory hormone (GnIH), a hypothalamic RFamide, has been found to inhibit gonadotrophin secretion from the anterior pituitary gland originally in birds and, subsequently, in mammalian species. The gene encoding a transmembrane receptor for GnIH (GnIHR) was recently identified in the brain, pituitary gland and gonads of song bird, chicken and Japanese quail. The objectives of the present study are to characterise the expression of GnIHR mRNA and protein in the chicken pituitary gland, and to determine whether sexual maturation and gonadal steroids influence pituitary GnIHR mRNA abundance. GnIHR mRNA quantity was found to be significantly higher in diencephalon compared to either anterior pituitary gland or ovaries. GnIHR mRNA quantity was significantly higher in the pituitaries of sexually immature chickens relative to sexually mature chickens. Oestradiol or a combination of oestradiol and progesterone treatment caused a significant decrease in pituitary GnIHR mRNA quantity relative to vehicle controls. GnIHR-immunoreactive (ir) cells were identified in the chicken pituitary gland cephalic and caudal lobes. Furthermore, GnIHR-ir cells were found to be colocalised with luteinising hormone (LH)beta mRNA-, or follicle-stimulating hormone (FSH)beta mRNA-containing cells. GnIH treatment significantly decreased LH release from anterior pituitary gland slices collected from sexually immature, but not from sexually mature chickens. Taken together, GnIHR gene expression is possibly down regulated in response to a surge in circulating oestradiol and progesterone levels as the chicken undergoes sexual maturation to allow gonadotrophin secretion. Furthermore, GnIHR protein expressed in FSHbeta or LHbeta mRNA-containing cells is likely to mediate the inhibitory effect of GnIH on LH and FSH secretion.

Altered response to metabolic challenges in mice with genetically targeted deletions of galanin-like peptide

Galanin-like peptide (GALP) is expressed in the arcuate nucleus and is implicated in the neuroendocrine regulation of metabolism and reproduction. To investigate the physiological significance of GALP, we generated and characterized a strain of mice with a genetically targeted deletion in the GALP gene [GALP knockout (KO) mice]. We report that GALP KO mice have a subtle, but notable, metabolic phenotype that becomes apparent during adaptation to changes in nutrition. GALP KO mice are indistinguishable from wild-type (WT) controls in virtually all aspects of growth, sexual development, body weight, food and water consumption, and motor behaviors, when they are allowed unlimited access to standard rodent chow. However, GALP KO mice have an altered response to changes in diet. 1) Male GALP KO mice consumed less food during refeeding after a fast than WT controls (P < 0.01). 2) GALP KO mice of both sexes gained less weight on a high-fat diet than WT controls (P < 0.01), despite both genotypes having consumed equal amounts of food. We conclude that although GALP signaling may not be essential for the maintenance of energy homeostasis under steady-state nutritional conditions, GALP may play a role in readjusting energy balance under changing nutritional circumstances.

Identification and characterization of two novel cytosolic sulfotransferases, SULT1 ST7 and SULT1 ST8, from zebrafish

Cytosolic sulfotransferases (SULTs) constitute a family of Phase II detoxification enzymes that are involved in the protection against potentially harmful xenobiotics as well as the regulation and homeostasis of endogenous compounds. Compared with humans and rodents, the zebrafish serves as an excellent model for studying the role of SULTs in the detoxification of environmental pollutants including environmental estrogens. By searching the expressed sequence tag database, two zebrafish cDNAs encoding putative SULTs were identified. Sequence analysis indicated that these two putative zebrafish SULTs belong to the SULT1 gene family. The recombinant form of these two novel zebrafish SULTs, designated SULT1 ST7 and SULT1 ST8, were expressed using the pGEX-2TK glutathione S-transferase (GST) gene fusion system and purified from transformed BL21 (DE3) cells. Purified GST-fusion protein form of SULT1 ST7 and SULT1 ST8 exhibited strong sulfating activities toward environmental estrogens, particularly hydroxylated polychlorinated biphenyls (PCBs), among various endogenous and xenobiotic compounds tested as substrates. pH-dependence experiments showed that SULT1 ST7 and SULT1 ST8 displayed pH optima at 6.5 and 8.0, respectively. Kinetic parameters of the two enzymes in catalyzing the sulfation of catechin and chlorogenic acid as well as 3-chloro-4-biphenylol were determined. Developmental expression experiments revealed distinct patterns of expression of SULT1 ST7 and SULT1 ST8 during embryonic development and throughout the larval stage onto maturity.

Epididymis expresses the highest 5'-deiodinase activity in the male reproductive system: kinetic characterization, distribution, and hormonal regulation

We characterized the enzymes that catalyze the deiodination of T(4) to T(3) in the male reproductive tract. Testis, epididymis (EPI), seminal vesicles, prostate, bulbourethral glands, spermatozoa, and semen were taken from sexually mature rats (300 g). Iodothyronine 5'-deiodinase (5'-D) activity was quantified by the radiolabeled-iodide-release method. 5'-D activity was 10-fold higher in EPI and semen than in the rest of the tissues. In EPI, semen, and prostate, the enzymatic activity was completely inhibited by 1 mm 6-n-propyl-2-thiouracil, whereas in the other tissues the inhibition was partial (50%). The high susceptibility to 6-n-propyl-2-thiouracil inhibition, a ping-pong kinetic pattern, and low cofactor (Michaelis Menten constant for dithiothreitol=0.7 mm) and high substrate (Michaelis Menten constant for reverse T(3)=0.4 microm) requirements indicate that EPI 5'-D corresponds to type 1 deiodinase (D1). Real-time RT-PCR amplification of D1 mRNA in this tissue confirms this conclusion. The highest EPI D1 expression occurred at the onset of puberty and sexual maturity, and in the adult, this activity was more abundant in corpus and caput than in the caudal region. EPI D1 expression was elevated under conditions of hyperthyroidism and with addition of 17beta-estradiol. Our data also showed a direct association between D1 and a functional epididymis marker, the neutral alpha-glucosidase enzyme, suggesting that local generation of T(3) could be associated with the development and function of EPI and/or spermatozoa maturation. Further studies are necessary to analyze the possible physiological relevance of 5'-D in the male reproductive system.

Gene injections of vascular endothelial growth factor and growth differentiation factor-9 stimulate ovarian follicular development in immature female rats

OBJECTIVE

To examine the effect of vascular endothelial growth factor (VEGF) and growth differentiation factor-9 (GDF-9) on follicular development of the ovaries in immature female rats.

DESIGN

Superovulation and gene injection.

SETTING

Animal reproduction laboratory in Tohoku University, Sendai, Japan.

ANIMAL(S)

Wister-Imamichi female rats.

INTERVENTION(S)

The ovulated oocytes from rats with injected VEGF and GDF-9 gene fragments were counted, and the ovaries removed from those rats were used in the histologic observation.

MAIN OUTCOME MEASURE(S)

Follicular dynamics and angiogenesis after VEGF and GDF-9 gene fragments injection.

RESULT(S)

A single injection of the VEGF gene led to the production of a large number of oocytes (approximately 110 oocytes) from an individual animal that was injected with the gene at 21 days after birth, and after mating most of the oocytes were fertilized. Direct ovarian injection of GDF-9 stimulated the development of medium-sized antral follicles. The number of ovulated oocytes after injection of the VEGF plus GDF-9 gene fragments was the same as with a single injection of the VEGF gene.

CONCLUSION(S)

A single injection of the VEGF or GDF-9 gene stimulated follicular development, and injection of both genes did increase the number of ovulated oocytes from individual animals. An exogenous gene fragments injection promoted the maximum potential of ovarian function in immature female rats.

Expression of steroidogenic enzymes and synthesis of steroid hormones during development of ovarian follicles in prepubertal goats

Expression of mRNAs encoding cytochrome P450 side-chain cleavage (P450scc), cytochrome P450 17 alpha-hydroxylase (P450c17), and cytochrome P450 aromatase (P450arom) were characterized by the RT-PCR technique and concentrations of progesterone (P4), testosterone (T0) and estradiol (E2) were measured by radioimmunoassay during follicular development of prepubertal goats. Synthesis of mRNAs encoding P450scc and P450c17 began in preantral follicles, but mRNA encoding P450arom was not detectable until early antral formation. While mRNA for P450scc was expressed in both theca and granulosa cells, mRNA for P450c17 was expressed only in theca cells while P450arom mRNA only in granulosa cells. In nonatretic follicles from prepubertal ovaries, the relative quantity of mRNA expression of all the three enzymes increased with follicle size; however, while the concentration of P4 and E2 increased, that of T0 decreased with follicle size. While expression of mRNA encoding P450scc was unaffected, that of P450c17 mRNA decreased to the lowest level and mRNA for P450arom became undetectable following atresia; accordingly, while the concentration of P4 increased in the atretic medium follicles, that of T0 and E2 decreased to the lowest level after atresia. While the adult follicular stage follicles showed a similar cytochrome expression as the nonatretic follicles of prepubertal goats, the former contained higher levels of E2 and P4 than the latter. The presence of corpus luteum in an ovary decreased expression of P450scc, significantly in large follicles while it increased concentration of P4. These findings indicated that (1) similar to other species, changes in follicular steroid production in goats were explained in large measure by changes in steroidogenic enzyme expression; (2) while mRNA expression was similar, activities of some of the steroidogenic enzymes may differ between sexually mature and immature goats.

GPR54 and rGnRH I gene expression during the onset of puberty in Nile tilapia

The Kiss1/GPR54 system has recently been shown to play a key role in the onset of puberty in mammals. Growing evidence suggests that this system is also conserved across vertebrates although very few studies so far have been performed in lower vertebrates. The aims of this study were firstly in the teleost Nile tilapia to screen tissues for GPR54 expression levels, secondly to measure the expression patterns of GPR54 and GnRH I receptor (rGnRH I) in whole brains during the onset of puberty and finally to determine the effects of continuous illumination (LL) on receptor expression levels. Results confirmed that GPR54 was predominantly expressed in the brain and pituitary of adult tilapia. Furthermore, a significant increase of GPR54 gene expression was found in tilapia brains at 11 weeks post hatch (wph) followed by rGnRH I at 13 wph just prior to the histological observation of vitellogenic oocytes and active spermatogenesis in ova and testes at 17 wph. These results suggest a correlation between the increase of GPR54 expression in the brain and the onset of puberty. Finally, a significant effect of LL was observed on GPR54 expression levels which were characterized by a delayed surge with significantly lower levels than those of control fish. The current study not only suggests a link between the Kiss1/GPR54 system and the onset of puberty in a tropical batch spawning teleost that would be a highly conserved feature across vertebrates but also that the transcriptional mechanisms regulating GPR54 expression could be directly or indirectly influenced by light.

Transition of leptin receptor expression during pubertal development in female rat pituitary

Leptin is thought to play important roles in pubertal development and reproductive function in the female. Leptin receptor is expressed in various tissues including the pituitary and hypothalamus. We investigated the transition of leptin receptor (Ob-R) expression in female rat pituitary during pubertal development. Real-time RT-PCR was performed for long-form leptin receptor (Ob-Rb) and short-form leptin receptor (Ob-Ra) in the pituitary and cerebrum of the rats aged 4 (juvenile), 6 (pubertal), and 8 weeks (adult). Double immunohistochemical colocalization of Ob-R and luteinizing hormone (LH) was performed in pituitaries from 4-week-old female rats. Serum leptin concentrations of 4-, 6-, and 8-week-old rats were measured by radioimmunoassay. In the pituitary, expression of Ob-Rb mRNA in 4-week-old rats (1.00 +/- 0.16) was significantly higher than in 8-week-old rats (0.61 +/- 0.07, p<0.05), although expression of Ob-Ra mRNA did not differ among 4-, 6-, and 8-week-old rats. In cerebrum, Ob-Ra and Ob-Rb mRNA expressions did not differ significantly among 4-, 6-, and 8-week-old rats. Intense staining of Ob-R and colocalization of Ob-R and LH were seen in 4-week-old rat pituitary. On the other hand, serum concentrations of leptin in 6- and 8-week-old rats were significantly higher than those in 4-week-old rats (p<0.05, p<0.01, respectively). In conclusion, since the pituitary gonadotroph is a potential target of leptin, the juvenile rat pituitary might prepare for a subsequent increase of serum leptin concentration by expressing Ob-Rb.

Molecular cloning of FSH and LH beta subunits and their regulation by estrogen in Atlantic croaker

The cDNAs of FSH and LH beta subunits were isolated from Atlantic croaker pituitary. The isolated genes in croaker showed 35-75% and 60-75% identities with FSH and LH beta of other teleosts, and 41% and 45% with human FSH and LH beta, respectively. The homology models of croaker FSH and LH beta were constructed using the currently known X-ray crystallography structures of human FSH beta and chorionic gonadotropin as templates. Real-time quantitative RT-PCR protocols were developed and validated to measure FSH and LH mRNAs. The FSH mRNA was higher in the pituitaries of early-pubertal croaker than that in late-maturing/mature individuals, whereas LH mRNA showed an opposite trend with substantially higher expression in late-maturing/mature fish. Administration of 17beta-estradiol (E(2); 1 and 5mug/g body weight) in early-pubertal fish significantly decreased FSH but increased LH mRNA expression in the pituitary. In late-maturing/mature females, gonadectomy significantly increased FSH mRNA while E(2) replacement suppressed the elevated expression. On the other hand, E(2) or gonadectomy with E(2) replacement did not significantly alter LH mRNA in the same experiment consistent with similar lack of effect on circulating LH levels in croaker described previously. This finding together with the existing evidence for estrogen negative feedback on GnRH-induced LH secretion in late-maturing/mature croaker suggests that the negative feedback mechanism does not involve inhibition of LH mRNA or protein and may be limited to the blockage of GnRH-induced LH release.

Direct glucocorticoid receptor-Stat5 interaction in hepatocytes controls body size and maturation-related gene expression

The glucocorticoid receptor regulates transcription through DNA binding as well as through cross-talk with other transcription factors. In hepatocytes, the glucocorticoid receptor is critical for normal postnatal growth. Using hepatocyte-specific and domain-selective mutations in the mouse we show that Stat5 in hepatocytes is essential for normal postnatal growth and that it mediates the growth-promoting effect of the glucocorticoid receptor through a direct interaction involving the N-terminal tetramerization domain of Stat5b. This interaction mediates a selective and unexpectedly extensive part of the transcriptional actions of these molecules since it controls the expression of gene sets involved in growth and sexual maturation.

NELL2, a neuron-specific EGF-like protein, is selectively expressed in glutamatergic neurons and contributes to the glutamatergic control of GnRH neurons at puberty

NELL2, a protein containing EGF-like repeats, is almost exclusively expressed in the nervous system. In the mammalian brain, NELL2 expression is mostly neuronal. NELL2 was previously found to be a secreted protein that functions during embryonic development as a neuronal differentiation and survival factor. We now show that the Nell2 gene is selectively expressed in the two major subtypes of glutamatergic neurons described in the postnatal brain: those containing the vesicular glutamate transporter 1 and those expressing vesicular glutamate transporter 2. No Nell2 mRNA is detected in GABAergic neurons. Likewise, GnRH neurons are devoid of NELL2. During prepubertal development of the female rat, Nell2 mRNA abundance increases selectively in the medial basal hypothalamus, reaching maximal values at the end of the juvenile period, to decline at the time of puberty to intermediate levels. Similar, but less pronounced changes are observed in the preoptic area, but they are absent in the cerebral cortex. A well-established glutamatergic function in the neuroendocrine brain is to enhance release of GnRH, the neurohormone controlling sexual development and the time of puberty. In vivo disruption of NELL2 synthesis via intraventricular administration of antisense oligodeoxynucleotides reduced GnRH release from the medial basal hypothalamus and delayed the initiation of female puberty. These results identify NELL2 as a new component of glutamatergic neurons and provide evidence for its physiological involvement in a major, glutamate-dependent, process of neuroendocrine regulation.

LHR splicing variants and gene expression in the marmoset monkey

In the marmoset monkey, the LHR type II, lacking exon 10, is the native receptor type. We characterised the LHR splicing pattern in marmoset testes and the adrenals during puberty and in pre- and postpubertal ovaries and quantified mRNA LHR expression in the testis. We detected 11 LHR splicing variants expressed at similar levels and generated by exon skipping and/or usage of cryptic splice sites. No preferred splicing variant during pubertal maturation was observed in both sexes. Testicular and adrenal LHR expression levels did not significantly change with age. However, a significant increase during pubertal maturation for the serum testosterone/LHR ratio indicated that testosterone secretion increases in the presence of constant LHR mRNA expression levels. We conclude that LHR splicing in the marmoset displays a homogenous pattern and that the main function of the LHR is established in the testis, reaching its highest efficiency during pubertal maturation.

Expression of a tumor-related gene network increases in the mammalian hypothalamus at the time of female puberty

Much has been learned in recent years about the central mechanisms controlling the initiation of mammalian puberty. It is now clear that this process requires the interactive participation of several genes. Using a combination of high throughput, molecular, and bioinformatics strategies, in combination with a system biology approach, we singled out from the hypothalamus of nonhuman primates and rats a group of related genes whose expression increases at the time of female puberty. Although these genes [henceforth termed tumor-related genes (TRGs)] have diverse cellular functions, they share the common feature of having been earlier identified as involved in tumor suppression/tumor formation. A prominent member of this group is KiSS1, a gene recently shown to be essential for the occurrence of puberty. Cis-regulatory analysis revealed the presence of a hierarchically arranged gene set containing five major hubs (CDP/CUTL1, MAF, p53, YY1, and USF2) controlling the network at the transcriptional level. In turn, these hubs are heavily connected to non-TRGs involved in the transcriptional regulation of the pubertal process. TRGs may be expressed in the mammalian hypothalamus as components of a regulatory gene network that facilitates and integrates cellular and cell-cell communication programs required for the acquisition of female reproductive competence.

Growth and pubertal development of F1 bulls from Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu sires1,2

The objective of the study was to characterize body growth, testicular development, and puberty from 8 to 14 mo of age in bulls (n = 120) produced by mating sires from Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu breeds to MARC III ((1/4) Hereford, (1/4) Angus, (1/4) Red Poll, and (1/4) Pinzgauer) cows. Traits evaluated were birth weight, weaning weight (at 215 d), yearling weight, ADG from 8 to 14 mo of age, paired testicular volume growth from 8 to 14 mo of age, age at puberty (determined by production of 50 x 10(6) sperm with 10% motility), age at freezable semen (determined by production of 500 x 10(6) sperm with 50% motility), and, at 15 mo of age, paired testicular weight and daily sperm production per testis pair. There was an effect of sire breed (P = 0.03) for age at puberty; animals with Wagyu and Swedish Red and White inheritance reached puberty at a later date (302 and 302 d of age, respectively) compared with Angus-sired bulls (268 d). Age at puberty for Hereford-, Norwegian Red-, and Friesian-sired bulls was 270, 271, and 278 d, respectively. Differences in BW were observed (P = 0.03) at birth; bulls with Hereford and Friesian were heavier at birth (43 and 41 kg, respectively) compared with those with Norwegian Red, Swedish Red and White, and Wagyu inheritance (39, 38, and 38 kg, respectively). Differences in BW were also observed at 1 yr of age (P = 0.001), where the heaviest animals were those sired by Angus (450 kg), whereas the lightest animals were those sired by Wagyu (403 kg). Bulls with Wagyu inheritance had the lowest (P = 0.04) ADG (1.12 kg/d) compared with bulls with inheritance from Hereford (1.22 kg/d), Angus (1.28 kg/d), Norwegian Red (1.24 kg/d), Swedish Red and White (1.25 kg/d), and Friesian (1.27 kg/d). Differences in scrotal growth rate were not significant (P = 0.99). They ranged from 1.95 in Angus-sired to 1.66 cm3/d in Wagyu-sired bulls. There were no differences (P = 0.80) for age at freezable semen (335 +/- 10 d). At slaughter (15 mo of age), there were no differences (P = 0.62) for paired testicular weight (603 +/- 28 g) and daily sperm production (10.6 x 10(9) +/- 0.9 x 10(9) per testis pair). Growth of bulls with Wagyu inheritance was slower, and bulls with Wagyu or Scandinavian inheritance reach puberty at an older age than bulls with Angus inheritance.

Enhanced at puberty 1 (EAP1) is a new transcriptional regulator of the female neuroendocrine reproductive axis

The initiation of mammalian puberty and the maintenance of female reproductive cycles are events controlled by hypothalamic neurons that secrete the decapeptide gonadotropin-releasing hormone (GnRH). GnRH secretion is, in turn, controlled by changes in neuronal and glial inputs to GnRH-producing neurons. The hierarchical control of the process is unknown, but it requires coordinated regulation of these cell-cell interactions. Here we report the functional characterization of a gene (termed enhanced at puberty 1 [EAP1]) that appears to act as an upstream transcriptional regulator of neuronal networks controlling female reproductive function. EAP1 expression increased selectively at puberty in both the nonhuman primate and rodent hypothalamus. EAP1 encoded a nuclear protein expressed in neurons involved in the inhibitory and facilitatory control of reproduction. EAP1 transactivated genes required for reproductive function, such as GNRH1, and repressed inhibitory genes, such as preproenkephalin. It contained a RING finger domain of the C3HC4 subclass required for this dual transcriptional activity. Inhibition of EAP1 expression, targeted to the rodent hypothalamus via lentivirus-mediated delivery of EAP1 siRNAs, delayed puberty, disrupted estrous cyclicity, and resulted in ovarian abnormalities. These results suggest that EAP1 is a transcriptional regulator that, acting within the neuroendocrine brain, contributes to controlling female reproductive function.

20 beta-hydroxysteroid dehydrogenase and CYP19A1 are differentially expressed during maturation in Atlantic cod (Gadus morhua)

In order to better quantify the molecular mechanisms regulating final oocyte maturation and spawning, complete coding sequences with partially or fully untranslated regions for the steroidogenic enzymes, cytochrome P450 aromatase and 20 beta-hydroxysteroid dehydrogenase, were cloned from ovaries of Atlantic cod (Gadus morhua). The nucleotide and amino acid sequences showed high homologies with the corresponding sequences of other fish species, and conserved features important for functionality were identified in both predicted proteins. The sequences of the corresponding genomic loci were also determined, allowing the design of mRNA-specific quantitative PCR assays. As a reference gene for the real-time RT-PCR assays, eukaryotic elongation factor 1 alpha was chosen, and the mRNA as well as the genomic sequence was determined. In addition, a real-time quantitative PCR assay for the 18S rRNA was adapted to be used in cod. Analysis of immature and maturing female cod from July to January respectively showed that the enzyme genes showed the expected quantitative changes associated with physiological regulation. However, mRNA for eukaryotic elongation factor 1 alpha, and to a lesser extent even 18S rRNA, showed variable expression in these samples as well. To find accurate standards for real-time PCR in such a dynamic organ as the cod ovary is not an easy task, and several possible solutions are discussed.

Noncoding RNAs of the mammalian testis: the meiotic transcripts Nct1 and Nct2 encode piRNAs

In eukaryotic cells, the vast majority of transcribed sequences are extragenic with no known functions. Translin is a DNA/RNA-binding protein involved in mRNA transport and translation in postmeiotic male germ cells. In an effort to identify meiotic target RNAs of Translin, reversible RNA protein cross-linking and immunoprecipitations with an affinity purified antibody to Translin were performed. Four new meiotically expressed mRNAs and one noncoding RNA with Translin binding sites were identified. Following sequencing, the noncoding RNA, Nct1, was 100% identical to a site on mouse chromosome 2. A second partially homologous sequence, Nct2, was detected nearby. Nct 1 and 2 contained sequences identical to piRNAs. Nct1 and 2 appear to be male germ cell-specific transcripts and are predominantly detected in pachytene spermatocytes. Focusing on the abundant single-copy PIWI-interacting RNA (piRNA), germline small RNA (gsRNA10) (the gsRNA10 sequence is identical to 29 nt in Nct1), we find that gsRNA10 increases greatly as spermatogenesis proceeds with concomitant decreases in Nct1 and 2. The piRNA gsRNA10 binds to the germ cell-specific Y-box protein, MSY2, but not to Translin. Although the size of the primary transcript(s) encoding the piRNAs in the locus on chromosome 2 is not known, we propose that Nct1 and 2 are part of a piRNA precursor.

Estimates of genetic correlations between days to calving and reproductive and weight traits in Nelore cattle

Data comprising 53,181 calving records were analyzed to estimate the genetic correlation between days to calving (DC), and days to first calving (DFC), and the following traits: scrotal circumference (SC), age at first calving (AFC), and weight adjusted for 550 d of age (W550) in a Nelore herd. (Co)variance components were estimated using the REML method fitting bivariate animal models. The fixed effects considered for DC were contemporary group, month of last calving, and age at breeding season (linear and quadratic effects). Contemporary groups were composed by herd, year, season, and management group at birth; herd and management group at weaning; herd, season, and management group at mating; and sex of calf and mating type (multiple sires, single sire, or AI). In DFC analysis, the same fixed effects were considered excluding the month of last calving. For DC, a repeatability animal model was applied. Noncalvers were not considered in analyses because an attempt to include them, attributing a penalty, did not improve the identification of genetic differences between animals. Heritability estimates ranged from 0.04 to 0.06 for DC, from 0.06 to 0.13 for DFC, from 0.42 to 0.44 for SC, from 0.06 to 0.08 for AFC, and was 0.30 for W550. The genetic correlation estimated between DC and SC was low and negative (-0.10), between DC and AFC was high and positive (0.76), and between DC and W550 was almost null (0.07). Similar results were found for genetic correlation estimates between DFC and SC (-0.14), AFC (0.94), and W550 (-0.02). The genetic correlation estimates indicate that the use of DC in the selection of beef cattle may promote favorable correlated responses to age at first mating and, consequently, higher gains in sexual precocity can be expected.

Effects of aroclor 1254 on the expression of the KAP3 gene and reproductive function in rats

The present study investigated the effects of aroclor 1254 (A1254) on the expression of the kinesin superfamily associated protein 3 (KAP3) gene in F1 rat brain during brain sexual differentiation and puberty. In addition, the effects of A1254 on reproductive function were examined. The KAP3 gene is involved in the neurogenesis and synaptogenesis of sexual differentiation in rats and also during puberty. In the present study, pregnant Sprague-Dawley rats each received a daily dose of A1254 (0, 10, 50 mg kg(-1)) dissolved in 1.0 mL corn oil by gavage, from gestational Day (GD) 8 to postnatal Day (PD) 21. The mRNA levels of the KAP3 gene in hypothalamic tissues were analysed by northern blot hybridisation during the critical periods of brain sexual differentiation (GD18 and PD5) and puberty (PD28). Variables affecting reproduction in F1 female rats, such as vaginal opening (VO), vaginal oestrus (VE) and oestrous cyclicity, were recorded. Depending on the sex and A1254 exposure (control or 50 mg kg(-1) day(-1)), F1 rats were divided into three mating groups, namely control male-control female, control male-A1254-treated female and A1254-treated male-control female. During the critical periods of brain sexual differentiation (GD18, PD5) and puberty (PD28), KAP3 mRNA levels were significantly reduced in A1254-treated fetal and pubertal rat brains relative to those of control groups. In A1254-treated F1 female rats, VO and VE were delayed, the percentage of irregular oestrous cycles was increased and the duration of the oestrous cycle was extended in a dose-dependent manner compared with control groups. Treatment with a high dose of A1254 significantly impaired the reproductive function of both male and female F1 rats, including mating and pregnancy indices and the number of live fetuses. These data suggest that A1254 disrupts transcriptional regulation of the KAP3 gene in fetal and pubertal rat brains and that these effects may be related to A1254-induced abnormal brain sexual differentiation and lowered reproductive function in F1 rats.

Consistency of Maturity Rate for Milk Yield Across Countries and Generations

Differences among bulls in maturity rate of their daughters for milk yield were investigated. Milk records for US Holsteins with first-parity calving dates between 1960 and 1998 were used to calculate 3 evaluations for bulls based on daughter records from parity 1, parities 1 and 2, and parities 1, 2, and 3. The 3 evaluations were used to estimate parity-specific evaluations for parities 2 and 3. Maturity rate of Holstein bull daughters in Canada and The Netherlands was compared with that for daughters of the same bulls in the United States by using official November 2004 Canadian and August 2005 Dutch parity-specific evaluations. For bulls with > or = 500 first-parity daughters, correlations among parity-specific evaluations within country and birth year of bull were 0.88 between parities 1 and 2, 0.84 between parities 1 and 3, and 0.96 between parities 2 and 3 for the United States; 0.90, 0.86, and 0.97, respectively, for Canada; and 0.92, 0.89, and 0.98, respectively, for The Netherlands. Correlations between Canada and the United States for within-country differences between evaluations for parities 1 and 2 were 0.72 for bulls with > or = 50 first-parity daughters and 0.89 for bulls with > or = 500 first-parity daughters; corresponding correlations between The Netherlands and the United States were 0.66 and 0.82. Correlations between countries for differences between evaluations for parities 1 and 3 were slightly less, and corresponding correlations between evaluations for parities 2 and 3 were still lower. To establish whether differences between parity-specific evaluations were genetic, comparisons were made across a generation. Coefficients for regression of son on sire within country and birth years of sire and son for parity-specific evaluations and differences between parity-specific evaluations ranged from 0.35 to 0.53, with standard errors of < or = 0.04. Differences in maturity rate of bull daughters were quite consistent across country, and those differences were transmitted to the sons' daughters. Modeling to account for maturity differences should increase the accuracy of US evaluations and reduce fluctuation between evaluations, especially for bulls with daughters that deviate substantially from the population mean for maturity rate for milk yield.

A Comparison of Three Strains of Holstein-Friesian Cows Grazed on Pasture: Growth, Development, and Puberty

With the introduction of a protein milk payment system in New Zealand in 1988, there was an influx of North American (NA) Holstein-Friesian (HF) genetics into New Zealand (NZ) dairy herds, leading to an increase in the average percentage of NA genetics in NZ HF cows--from 2% in 1980 to 38% in 1999. Of interest has been the effect this change has had on farm profitability and on the management required for these animals, as well as the phenotypic changes that have occurred within the national herd under the breeding programs operated in NZ from 1970 to 1990. The objective of this study was to quantify differences in body dimensions, body weights, and puberty-related parameters among 3 strains of HF, representing animals of NZ origin representative of the genetics present in 1970 and 1990 and of NA origin with 1990s genetics. A total of 172 animals born in 1999 were compared. The strains were 1) NZ70, a strain of NZ Friesian (average 7% NA genetics) equivalent to high-genetic-merit (high Breeding Worth) cows farmed in the 1970s; 2) NZ90, a strain of HF of NZ origin (average 24% NA genetics) typical of the animals present in the 1990s; and 3) NA90, a strain of HF of NA origin (average of 91% NA genetics) typical of animals present in the 1990s. The differences in BW among all strains were significant at 6 and 12 mo of age. At 15 and 24 mo, the 2 NZ strains were significantly lighter than the NA90 animals. At 24 mo of age (i.e., prior to first calving), the NA90 strain animals (BW = 515 kg) were 22 and 34 kg heavier than the NZ90 and NZ70 strains. The body length of the NA90 strain was greater than either of the 2 NZ strains; the differences among the NA90 strain and the 2 NZ strains varied from 2 to 6 cm, with the differences generally being greater at older ages. The trend in heart girth difference among strains was similar to that observed for body length. The wither height of the NA90 animals was greater than that of the NZ strains by 1 to 7 cm, although there was no significant difference between the NA90 and NZ90 strains at birth. At puberty the NA90 heifers were 20 d older and 20 kg heavier than the NZ90 heifers, which in turn were 25 kg and 25 d older than the NZ70 heifers. The NA90 strain had a heavier mature body weight, and their older age at puberty suggested either that they mature later or that, under pastoral conditions, their growth rate is limited by their inability to consume sufficient metabolizable energy as grazed pasture, with a consequent delay in puberty. Results from this study will be useful in revising target BW in growing heifers of different germplasm.

Ciliated epithelial-specific and regional-specific expression and regulation of the estrogen receptor-beta2 in the fallopian tubes of immature rats: a possible mechanism for estrogen-mediated transport process in vivo

Several ERbeta isoforms have been identified in human and rodent tissues, but it is unclear whether each isoform has distinctly different cellular targeting characteristics and physiological functions. We have investigated the intracellular localization and regulatory patterns for ERbeta isoforms in rat fallopian tubes. Western blot analysis reveals that two ERbeta isoforms corresponding to ERbeta1 and ERbeta2 are expressed in rat fallopian tubes. However, ERbeta2 is the predominant form of ERbeta in this tissue. High-resolution confocal imaging and immunohistochemical analysis provide ample evidence that ERbeta expression is limited almost exclusively to the ciliated epithelial cells, in contrast to ERalpha, which is widely distributed. Furthermore, within the ciliated epithelial cells, ERbeta is colocalized with beta-tubulin IV at stem portion of the cilia. We show that ERbeta2 protein expression is tightly regulated by E(2) or DPN in a time-dependent manner without changes in ERbeta1 expression. These estrogenic effects are inhibited by an ER antagonist, ICI 182,780. In addition, significant alteration of ERbeta immunoreactivity is detected only histologically in the ampullary region. Since the cilia are considered an essential determinant of tubal transport, we further demonstrate that E(2)- or DPN-induced ERbeta2 activation is associated with alterations in tubal protein expression crucial for the regulation of calcium-dependent ciliary beating. Given the coordinated regulation and interaction of ER and progesterone receptor in the cilia, we hypothesize that tubal ERbeta2 may facilitate the estrogen-mediated transport process by processing protein-protein interaction under physiological and/or pathological conditions. We show for the first time that a previously unrecognized localization of ERbeta isoform in rat fallopian tubes can combine with estrogen to individually control the expression of ER beta-isoforms in normal target tissues.