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R Patiño

Publications and source records attributed to R Patiño.

At least 19 recordsLinked to original sources
PubMed2001

Localization of estrogen receptor alpha and beta RNA in germinal and nongerminal epithelia of the channel catfish testis.

The germinal epithelium of the anterior region of the channel catfish testis is the site of spermatogenesis, whereas the nongerminal epithelium of the posterior region (seminal vesicle) may play a role in the regulation of seminal fluid composition. The available information indicates that estrogens play a physiological role in the regulation of spermatogenesis and seminal fluid composition in vertebrates. However, the cellular distribution of estrogen receptor (ER) gene expression in the teleost testis is poorly understood. Therefore, the objective of this study was to determine the presence and cellular distribution of ERalpha and ERbeta transcripts in germinal and nongerminal epithelia of the mature testis of channel catfish. RT-PCR of whole-testis RNA extracts showed that ERalpha and ERbeta RNAs are present in the mature testis. In situ hybridization of histological sections of the germinal epithelium showed that primary spermatocytes contain little or no ERalpha or ERbeta RNA. However, both ER transcripts were present in secondary spermatocytes and spermatids and their levels were relatively high in mature sperm. The columnar epithelium of the seminal vesicle also contained ERalpha and ERbeta RNA. The ER RNAs in epithelial cells of the seminal vesicle were not evenly distributed throughout the cytoplasm but seemed to concentrate in their apical region, near the nucleus. In conclusion, ERalpha and ERbeta genes are coexpressed in germinal and nongerminal epithelia of the mature testis of channel catfish and seem to be developmentally regulated in spermatocytes. These observations are consistent with the concept that estrogens, via interaction with ERalpha and ERbeta, participate in the regulation of male gamete development and fertility.

Animals↗
PubMed2001

Effects of maturation-inducing hormone on heterologous gap junctional coupling in ovarian follicles of Atlantic croaker.

A previous ultrastructural study of heterologous (granulosa cell-oocyte) gap junction (GJ) contacts in ovarian follicles of Atlantic croaker suggested that these contacts disappear late during the process of resumption of oocyte meiosis. This observation suggested that, unlike scenarios proposed for a number of other species, uncoupling of GJ is not necessary for the onset of meiotic resumption in croaker follicles. However, the functionality of heterologous GJ contacts and the temporal association between maturation-inducing hormone (MIH)-induced changes in heterologous coupling and resumption of oocyte meiosis have not been examined in Atlantic croaker. These questions were addressed with a cell-cell coupling assay that is based on the transfer of a GJ marker, Lucifer Yellow, from oocytes to granulosa cells. Follicle-enclosed oocytes injected with Lucifer Yellow allowed transfer of the dye into the follicle cell layer, thus confirming that there is functional heterologous coupling between the oocyte and the granulosa cells. Dye transfer was observed in vitellogenic, full-grown/maturation-incompetent, and full-grown/maturation-competent follicles. Treatment of maturation-competent follicles with MIH caused a time-dependent decline in the number of follicles transferring dye. However, although GJ uncoupling in some of the follicles was observed before germinal vesicle breakdown (GVBD, index of meiotic resumption), about 50% of the follicles maintained the ability to transfer dye even after GVBD had occurred. Further, a known GJ inhibitor (phorbol 12-myristate 13-acetate) blocked heterologous GJ within a time frame similar to that seen with MIH but without inducing any of the morphological changes (including GVBD) associated with follicular maturation. In conclusion, uncoupling of heterologous GJ seems insufficient and unnecessary for the onset of meiotic resumption in ovarian follicles of Atlantic croaker.

Animals↗
PubMed2001

Gonadotropic control of ovarian follicle maturation: the two-stage concept and its mechanisms.

Most research on the control of oocyte maturation by luteinizing hormone (LH) in teleosts and amphibians has focused on the production and action of maturation-inducing hormone (MIH), the follicular hormone that directly triggers the resumption of oocyte meiosis. However, current information indicates that LH regulates maturation in two stages, and that 'oocyte maturation' can be appropriately described within the broader context of 'ovarian follicle maturation'. During the first stage of maturation the follicle (somatic) cells acquire the ability to produce MIH and the oocyte to respond to MIH (i.e. oocyte maturational competence, OMC), whereas in the second stage the follicle cells produce MIH and, consequently, the oocyte is released from meiotic arrest. A number of factors such as insulin-like growth factor-I, serotonin, and others may mediate or modulate the OMC-inducing action of LH. Like the acquisition of MIH-producing ability, the acquisition of OMC requires activation of the protein kinase A pathway. Two major cellular events associated with OMC acquisition are increases in homologous and heterologous gap junction contacts and in oocyte MIH receptor activity. The increased oocyte MIH receptor activity is presumably associated with OMC acquisition, but the significance of changes in gap junction contacts is at present uncertain. To eliminate inconsistency and ambiguity associated with current terminology we propose that the term, ovarian follicle (or oocyte) maturation be used for teleosts without qualifiers such as 'final' to define the first and second stages of follicular maturation.

Animals↗
PubMed2001

Expression of connexin 43 mRNA and protein in developing follicles of prepubertal porcine ovaries.

A major form of cell-cell communication is mediated by gap junctions, aggregations of intercellular channels composed of connexins (Cxs), which are responsible for exchange of low molecular weight (<1200 Da) cytosolic materials. These channels are a growing family of related proteins. This study was designed to determine the ontogeny of connexin 43 (Cx43) during early stages of follicular development in prepubertal porcine ovaries. A partial-length (412 base) cDNA clone was obtained from mature porcine ovaries and determined to have 98% identity with published porcine Cx43. Northern blot analysis demonstrated a 4.3-kb mRNA in total RNA isolated from prepubertal and adult porcine ovaries. In-situ hybridization revealed that Cx43 mRNA was detectable in granulosa cells of primary follicles but undetectable in dormant primordial follicles. The intensity of the signal increased with follicular growth and was greatest in the large antral follicles. Immunohistochemical evaluation indicated that Cx43 protein expression correlated with the presence of Cx43 mRNA. These results indicate that substantial amounts of Cx43 are first expressed in granulosa cells following activation of follicular development and that this expression increases throughout follicular growth and maturation. These findings suggest an association between the enhancement of intercellular gap-junctional communication and onset of follicular growth.

Age Factors↗
PubMed2000

Circulating monocytes in patients with diabetes mellitus, arterial disease, and increased CD14 expression.

Low serum concentrations of high-density lipoprotein (HDL) cholesterol and elevated levels of acute-phase reactans are frequently found in patients with non-insulin-dependent diabetes mellitus (NIDDM) and cardiovascular disease. Changes in the phenotype of circulating monocytes have been reported with both of these circumstances in nondiabetic subjects. In the present study, we explored the possibility that similar changes may occur in circulating monocytes of patients with NIDDM and arterial disease. Two groups of subjects with NIDDM were studied: patients with cardiovascular disease (n = 25) were compared with a group without cardiovascular disease (n = 26); both groups were age- and sex-matched, had the same length of diabetes duration, and degree of glycemic control. Healthy nondiabetic volunteers of comparable age and sex (n = 35) formed the control group. There was no significant difference in the numbers of the CD14+/CD16+ monocyte subpopulations between the 3 groups. However, a significant graded increase of the mCD14 intensity expression values was observed among the groups, with the highest levels in patients with NIDDM patients and the lowest in nondiabetic subjects. The serum C-reactive protein concentrations were significantly higher in the group with arterial disease compared with those without arterial disease or healthy controls. In the group of patients as a whole, relative mCD14 intensity expression was significantly correlated with HDL cholesterol levels (inversely) and with serum concentrations of C-reactive protein. Serum HDL cholesterol levels and the C-reactive protein concentrations were also significantly correlated. We concluded that the increased mCD14 intensity expression on circulating monocytes may be an important contributor to the increased inflammatory response observed in patients with NIDDM and arterial disease, and eventually, to atherogenesis.

Aged↗
PubMed2000

Phylogenetic sequence analysis, recombinant expression, and tissue distribution of a channel catfish estrogen receptor beta.

An estrogen receptor beta (ERbeta) cDNA fragment was amplified by RT-PCR of total RNA extracted from liver and ovary of immature channel catfish. This cDNA fragment was used to screen an ovarian cDNA library made from an immature female fish. A clone was obtained that contained an open reading frame encoding a 575-amino-acid protein with a deduced molecular weight of 63.9 kDa. Maximum parsimony and Neighbor Joining analyses were used to generate a phylogenetic classification of channel catfish ERbeta on the basis of 25 full-length teleost and tetrapod ER sequences. The consensus tree obtained indicated the existence of two major vertebrate ER subtypes, alpha and beta. Within each subtype, and in accordance with established phylogenetic relationships, teleost and tetrapod ER were monophyletic confirming the results of a previous analysis (Z. Xia et al., 1999, Gen. Comp. Endocrinol. 113, 360-368). Extracts of COS-7 cells transfected with channel catfish ERbeta cDNA bound estrogen with high affinity (K(d) = 0.21 nM) and specificity. The affinity of channel catfish ERbeta for estrogen was higher than previously reported for channel catfish ERalpha. As determined by qualitative RT-PCR, the tissue distributions of ERalpha and ERbeta were similar but not identical. Both ER subtypes were present in ovary and testis. ERalpha was found in all other tissues examined from juvenile and mature fish of both sexes. ERbeta was also found in most tissues except, in most cases, whole blood and head kidney. Interestingly, the pattern of expression of ER subtypes in head kidney always corresponded to the pattern in whole blood. In conclusion, we isolated a channel catfish ERbeta with ligand-binding affinity and tissue expression patterns different from ERalpha. Also, we confirmed the validity of our previously proposed general classification scheme for vertebrate ER into alpha and beta subtypes and within each subtype, into teleost and tetrapod clades.

Amino Acid Sequence↗
PubMed2000

Hormonal regulation and cellular distribution of connexin 32.2 and connexin 32.7 RNAs in the ovary of Atlantic croaker.

The in vitro effects of human chorionic gonadotropin (hCG) on ovarian connexin (Cx) 32.2 and 32.7 RNA levels and ovarian follicle maturation were assessed, and the cellular distribution of Cx transcripts in the ovary was determined. hCG caused a concentration-dependent induction of Cx32.2 RNA, which peaked coincidentally with the appearance of morphological indices of oocyte maturational competence (OMC). Cx32.2 RNA levels declined thereafter in all treatment groups, although this decline was not accompanied by the onset of germinal vesicle breakdown (GVBD) at the lowest hCG concentration used. The levels of Cx32.7 RNA initially declined and subsequently increased to preincubation values after hCG treatment, but these changes were not dependent on hCG concentration. In a separate experiment, the decline in Cx32.7 RNA occurred in the presence or absence of hCG and was prevented by low (physiological) concentrations of estradiol-17beta (E2) or by protein kinase C (PKC) inhibitor, but was enhanced in the presence of high E2 concentrations or of PKC activator. These changes in Cx32. 7 RNA abundance were not associated with any indices of oocyte maturation. In situ hybridization of tissue sections showed the presence of Cx32.2 and Cx32.7 RNA in somatic cells of the ovarian follicle but not in oocytes. Cx32.2 RNA seemed to be present in granulosa and thecal cells, but the assay resolution was insufficient to reliably determine the distribution of Cx32.7 transcript by somatic cell type. In view of earlier findings that Cx32.2-based (but not Cx32.7-based) connexons can form functional homotypic channels, these results indicate that Cx32.2 gene expression in granulosa cells is sufficient for the formation of homologous gap junctions (GJ). Northern blot of RNA extracts from ovulated eggs, which are free of follicle cells, showed the presence of relatively low levels of both Cx RNAs. Thus, it is possible that Cx32.2 is present in oocytes and that it participates in heterologous (homotypic) GJ formation between the oocyte and the granulosa cells. In conclusion, Cx32.2 RNA levels in somatic cells of the ovarian follicle correlated positively with morphological indices of OMC acquisition, but subsequently declined during GVBD. These changes in Cx32.2 RNA may function in the regulation of GJ contacts during follicular maturation.

Animals↗
PubMed2000

Novel transcripts of the estrogen receptor alpha gene in channel catfish.

Complementary DNA libraries from liver and ovary of an immature female channel catfish were screened with a homologous ERalpha cDNA probe. The hepatic library yielded two new channel catfish ER cDNAs that encode N-terminal ERalpha variants of different sizes. Relative to the catfish ERalpha (medium size; 581 residues) previously reported, these new cDNAs encode Long-ERalpha (36 residues longer) and Short-ERalpha (389 residues shorter). The 5'-end of Long-ERalpha cDNA is identical to that of Medium-ERalpha but has an additional 503-bp segment with an upstream, in-frame translation-start codon. Recombinant Long-ERalpha binds estrogen with high affinity (K(d) = 3. 4 nM), similar to that previously reported for Medium-ERalpha but lower than reported for catfish ERbeta. Short-ERalpha cDNA encodes a protein that lacks most of the receptor protein and does not bind estrogen. Northern hybridization confirmed the existence of multiple hepatic ERalpha RNAs that include the size range of the ERalpha cDNAs obtained from the libraries as well as additional sizes. Using primers for RT-PCR that target locations internal to the protein-coding sequence, we also established the presence of several ERalpha cDNA variants with in-frame insertions in the ligand-binding and DNA-binding domains and in-frame or out-of-frame deletions in the ligand-binding domain. These internal variants showed patterns of expression that differed between the ovary and liver. Further, the ovarian library yielded a full-length, ERalpha antisense cDNA containing a poly(A) signal and tail. A limited survey of histological preparations from juvenile catfish by in situ hybridization using directionally synthesized cRNA probes also suggested the expression of ERalpha antisense RNA in a tissue-specific manner. In conclusion, channel catfish seemingly have three broad classes of ERalpha mRNA variants: those encoding N-terminal truncated variants, those encoding internal variants (including C-terminal truncated variants), and antisense mRNA. The sense variants may encode functional ERalpha or related proteins that modulate ERalpha or ERbeta activity. The existence of ER antisense mRNA is reported in this study for the first time. Its role may be to participate in the regulation of ER gene expression.

3' Untranslated Regions↗
PubMed2000

Structural Organization of the Atlantic Croaker Connexin 32.2 Gene and Its 5' Flanking Region.

Gonadotropic hormone stimulates the accumulation of connexin (Cx) 32.2 messenger RNA in ovaries of the marine teleost Atlantic croaker. This effect can be mimicked by protein kinase A (PKA) activators and blocked by PKA inhibitors as well as protein kinase C (PKC) stimulators. However, the mechanisms of Cx32.2 gene regulation are unknown. In this study, we determined the structure of the Cx32.2 gene as a first step toward characterizing the regulatory mechanisms of Cx32.2 gene expression. A cosmid library of croaker genomic DNA was screened with a Cx32.2 complementary DNA probe. One positive clone was subcloned and sequenced. The Cx32.2 gene contained two exons and one intron. The first exon contained a portion of the 5' untranslated region (UTR), and the second exon contained the remaining 5' UTR, the amino acid coding region, and the 3' UTR. The distal 5' flanking region also contained a sequence homologous to a different croaker Cx gene, Cx32.7, but it is unclear if this sequence constitutes a pseudogene or an exon of the Cx32.7 gene. The 5' flanking region of the Cx32.2 gene contained two core cyclic AMP response elements (CRE, CGTCA) and one full-consensus activating protein- (AP)-1 binding site (AGTCAG). The distal core CRE was associated with a sequence that enhances CRE activity (GAGC). A third core CRE site was present in the intron. These findings are consistent with the following hypotheses: the induction of ovarian Cx32.2 mRNA levels by gonadotropic hormone is at least partly mediated by CRE-dependent activation of the Cx32.2 gene, and the inhibition of basal and gonadotropic-hormone-stimulated ovarian Cx32.2 mRNA by PKC is due to negative effects on transcription via the AP-1 transcription factor complex. This study is the first to characterize the structure and putative response elements of the 5' flanking region of fish Cx genes.

Journal Article↗
PubMed1999

Cloning, in vitro expression, and novel phylogenetic classification of a channel catfish estrogen receptor.

We obtained two channel catfish estrogen receptor (ccER) cDNA from liver of female fish using RT-PCR. The two fragments were identical in sequence except that the smaller one had an out-of-frame deletion in the E domain, suggesting the existence of ccER splice variants. The larger fragment was used to screen a cDNA library from liver of a prepubescent female. A cDNA was obtained that encoded a 581-amino-acid ER with a deduced molecular weight of 63.8 kDa. Extracts of COS-7 cells transfected with ccER cDNA bound estrogen with high affinity (Kd = 4.7 nM) and specificity. Maximum parsimony and Neighbor Joining analyses were used to generate a phylogenetic classification of ccER on the basis of 18 full-length ER sequences. The tree suggested the existence of two major ER branches. One branch contained two clearly divergent clades which included all piscine ER (except Japanese eel ER) and all tetrapod ERalpha, respectively. The second major branch contained the eel ER and the mammalian ERbeta. The high degree of divergence between the eel ER and mammalian ERbeta suggested that they also represent distinct piscine and tetrapod ER. These data suggest that ERalpha and ERbeta are present throughout vertebrates and that these two major ER types evolved by duplication of an ancestral ER gene. Sequence alignments with other members of the nuclear hormone receptor superfamily indicated the presence of 8 amino acids in the E domain that align exclusively among ER. Four of these amino acids have not received prior research attention and their function is unknown. The novel finding of putative ER splice variants in a nonmammalian vertebrate and the novel phylogenetic classification of ER offer new perspectives in understanding the diversification and function of ER.

Amino Acid Sequence↗
PubMed1999

Developmental and protein kinase-dependent regulation of ovarian connexin mRNA and oocyte maturational competence in Atlantic croaker.

The acquisition of oocyte maturational competence (OMC) in ovarian follicles of Atlantic croaker is associated with increased gap junction (GJ) contacts and increased levels of ovarian connexin (Cx) 32.2 mRNA. However, the developmental control of ovarian Cx gene expression and the mechanisms of OMC acquisition are unknown. Ovarian Cx32.2 and Cx32.7 mRNA levels were determined in fish with gonadosomatic indices (GSI; gonad weight-to-body weight ratio) ranging from 0.1 to 13%. The mRNA level for both Cx increased from a low level in previtellogenic ovaries (GSI, <1%) to a peak level during the midstage of ovarian growth (GSI, 6-7%). Levels of Cx32.2 mRNA, but not Cx32.7 mRNA, declined markedly during late ovarian vitellogenic growth (GSI, 7-13%), and increased again upon stimulation of OMC by human chorionic gonadotropin (hCG). These changes in ovarian Cx32.2 mRNA seem to parallel previously reported changes in the incidence of oocyte-granulosa cell GJ during follicular growth and early maturation. In vitro treatment with hCG and protein kinase A (PKA) activators (dbcAMP and forskolin) induced ovarian Cx32.2 mRNA levels and OMC. The effects of hCG were blocked by PKA inhibitors (H89, H7). Protein kinase C (PKC) inhibitors (GF 109207X) had little effect on hCG-induced Cx32.2 mRNA or OMC, whereas PKC activators (PMA) blocked both events. There was no association between changes in Cx32.7 mRNA levels and OMC status in these experiments. In conclusion, changes in Cx32.2 gene expression seem to be involved in the regulation of oocyte-granulosa cell GJ during growth and differentiation of the croaker ovarian follicle. Also, the stimulation of OMC and Cx32.2 mRNA levels by hCG is mediated by PKA-dependent pathways and antagonized by PKC-dependent mechanisms.

Animals↗
PubMed1999

Regulation of gap junctions and oocyte maturational competence by gonadotropin and insulin-like growth factor-I in ovarian follicles of red seabream.

The in vitro effects of human chorionic gonadotropin (hCG) and human insulin-like growth factor-I (IGF-I) on the formation of oocyte-granulosa cell (heterologous) and granulosa cell-granulosa cell (homologous) gap junctions (GJ) were determined during the course of development of oocyte maturational competence (OMC) in ovarian follicles of red seabream. Incompetent, full-grown follicles were incubated in hCG (10 IU/ml), IGF-I (10 nM), or hormone-free medium for 0, 6, and 12 h and examined by electron microscopy. Qualitative analysis indicated that homologous and heterologous GJ were relatively rare in incompetent follicles and remained rare if they were maintained in control medium. However, both types of GJ were readily observed in follicles treated with hCG or IGF-I. For quantitative analysis, we measured changes in the combined numbers of both GJ types, since discrimination between the two was not always possible. The numbers of GJ along 125 micrometer of granulosa cell-zona radiata border were counted in three follicles/treatment. GJ markedly increased with time in the presence of hCG or IGF-I but not in control medium (Duncan's multiple range test; P < 0.05). Functional assays confirmed that the hormonal treatments also induced OMC. Naturally competent follicles sampled at the appropriate stage of the reproductive cycle contained high levels of both types of GJ suggesting that the OMC-associated increase in GJ is physiologically relevant. In view of similar, earlier results with the Atlantic croaker, the present results support the concept that an increase in homologous and heterologous GJ is a general developmental event associated with the acquisition of OMC in teleost ovarian follicles. Also, a novel finding of this study is that IGF-I can regulate heterologous and homologous GJ in intact ovarian follicles.

Animals↗
PubMed1996

Increased serum levels of IgA antibodies to hsp70 protein in patients with diabetes mellitus: their relationship with vascular complications.

We measured class-specific antibodies to the mycobacterial hsp70 protein in 67 patients with diabetes mellitus (27 type 1 and 40 type 2) with or without vascular complications. Using ELISA, the levels of IgG and IgM antibodies in the sera of diabetic patients did not significantly differ either from those of healthy control subjects or between both types of diabetes, regardless of gender, disease duration, HbA1 level, or type of vascular complication. In patients with type 2 diabetes, the mean serum IgA levels were significantly higher than those in their matched controls [274(71) mg/dl vs 208(88) mg/dl; P < 0.01]. In this group of patients, the IgA antibody titer was significantly correlated to the serum IgA level (r = 0.334; P < 0.01). Serological autoimmunity (IgG or IgM type) to hsp70 protein is common in both the normal and the diabetic population. The increased IgA levels and anti-hsp70 IgA titers in the sera of diabetics suggest a possible role of IgA in the pathogenesis of the vascular complications of diabetes mellitus.

Adult↗
PubMed1995

Intercellular channels in teleosts: functional characterization of two connexins from Atlantic croaker.

Gap junction channels, composed of protein subunits termed connexins, are believed to play a critical role in the process of oocyte differentiation and maturation. We have used the paired Xenopus oocyte assay to characterize functionally two connexin genes, connexin-32.2 and connexin-32.7, recently cloned from the ovary of the Atlantic croaker (Micropogonia undulatus), a species that has emerged as a useful model to study the process of maturation of the ovarian follicle. We have found that, while both connexin proteins were expressed at comparable levels in Xenopus oocytes, only one, connexin-32.2, was functionally competent to induce the formation of intercellular channels. Connexin-32.2 channels exhibited voltage-dependent closure that was similar to, but distinct from that of previously characterized mammalian connexins. In addition, the silent connexin-32.7 was unable to functionally interact with connexin-32.2, either in heterotypic channels or as dominant negative inhibitor. Because connexin-32.2 expression is strikingly regulated during oocyte maturation, these data provide further evidence for a role of intercellular channels in the control of oocyte-follicular cell interactions.

Animals↗
PubMed1995

Molecular cloning, tissue distribution, and hormonal control in the ovary of Cx41 mRNA, a novel Xenopus connexin gene transcript.

Gap junctions (GJ) are aggregates of intercellular channels, composed of connexin (Cx) protein, between adjacent cells. The vertebrate ovarian follicle contains homocellular (granulosa cell-granulosa cell) and heterocellular (granulosa cell-oocyte) GJ. However, the function of GJ during final oocyte differentiation (maturation) is controversial. The objectives of this study are to reexamine the number and identity of Cx genes that are expressed in the Xenopus ovary, and to examine the potential role of GJ in oocyte maturation by determining the temporal association between changes in ovarian Cx mRNA content and the process of maturation. We used reverse transcriptase-polymerase chain reaction to amplify ovarian cDNA fragments using degenerate Cx primers. We amplified three Cx-like fragments: one was novel and two corresponded to known Cx of Xenopus ovaries (Cx38 and 43). The novel fragment was used to screen an ovarian cDNA library. One positive clone was identified and its nucleotide sequence determined. Its deduced amino acid sequence showed that it corresponded to a novel Cx, Cx41, belonging to the Group II class of Cx. Xenopus Cx41 showed the highest homology to rat Cx37 (65% identity, 80% similarity). Also, the last 10 C-terminal amino acids of Cx41 were identical to those of rat, mouse, and human Cx37. Cx41 transcripts were detected by riboprobe mapping in ovarian somatic cells, heart, leg muscle, liver and eye, but not in brain or in oocytes of any developmental stage. Full-grown follicles incubated in vitro with human chorionic gonadotropin became committed to mature within 1-4 hr, and physical signs of maturation (germinal vesicle breakdown) were seen at 4-5 hr. Significant reductions in the levels of Cx41 and 43, but not 38 transcripts were seen at 4 hr, after oocytes had committed to mature. Thus, if availability of Cx mRNA determines availability of Cx protein and GJ, our results would suggest that irreversible commitment to maturation occurred prior to major declines in follicular GJ during the periovulatory period. The present study is the first to report the presence of at least two hormone-responsive Cx gene transcripts (Cx41 and 43 in Xenopus) in ovaries of a single animal species.

Amino Acid Sequence↗
PubMed1995

A simulated insect diet as a water source for quail: effects on body mass and reproduction.

Compared with control birds receiving ad libitum free-water, the total water intake of male and female northern bobwhite declined when only mealworms were available as a source of water. Male northern bobwhite sustained tissue mass and reproductive function with mealworms as their only source of water. Female northern bobwhite could not sustain body, ovary, and oviduct mass, and rate of egg production with mealworms as their only source of water. We suggest that, without free-water, breeding females require a diet with a water:dry matter ratio of greater than 1:1.29 (> 44% water).

Animal Feed↗
PubMed1994

Connexin messenger ribonucleic acids in the ovary of Atlantic croaker: molecular cloning and characterization, hormonal control, and correlation with appearance of oocyte maturational competence.

Intercellular gap junction channels are composed of connexin (Cx) protein. In the Atlantic croaker ovary, gonadotropin (GtH)-induced oocyte maturational competence is accompanied by an obligatory synthesis of RNA and protein and by the formation of granulosa cell-oocyte gap junctions. However, the GtH control of Cx gene expression in relation to follicular differentiation (including maturational competence) has not been examined in Atlantic croaker or in any other vertebrate species. Moreover, Cx genes and their products have not been characterized in fishes. Therefore, the objectives of this study were to characterize ovarian Cx mRNAs in Atlantic croaker and to determine their regulation by GtH during the acquisition of maturational competence. Polymerase chain reaction was used to amplify Cx cDNA prepared from maturationally incompetent or competent ovaries. Mixed primers for this reaction were based on the high sequence homology of selected regions of known connexins. One major fragment (Cx1) was amplified from incompetent ovary cDNA, and two major fragments (Cx1' and Cx2) from competent ovary cDNA. Sequence analysis showed that Cx1 and Cx1' are identical and that Cx1 and Cx2 have high sequence homology to other Cx cDNAs. A cDNA library made from competent ovaries was screened with Cx1 or Cx2 used as probes. Two cDNAs were isolated: one (Cx1) encoded 282 amino acids (32,693 daltons; Cx32.7), and the other (Cx2) encoded 285 amino acids (32,169 daltons; Cx32.2). Both amino acid sequences showed all key features of Cx. Northern blot analysis showed a negligible level of Cx32.2 mRNA in incompetent ovaries, but a substantial rise in its levels accompanied the GtH induction of maturational competence. However, Cx32.7 mRNA levels in incompetent and competent ovaries were similar. In conclusion, selective activation of the ovarian Cx32.2 gene by GtH seems to occur during the acquisition of oocyte maturational competence.

Amino Acid Sequence↗