Interaction of granulosa and theca layers in the control of progesterone secretion in the domestic hen

The ovulatory cycle of the domestic hen is approximately 26 h in length. The hen ovulates an egg each day at a progressively later time until she finally skips a day, resets her "clock" and a new sequence is started. The ovarian component of this unique timing mechanism is the focus of this report. In Experiment 1, we asked whether there was a difference in luteinizing hormone (LH)-stimulated progesterone (P4) secretion by the granulosa layer removed from the largest follicle (F1) that had been the F1 follicle for 8, 12, or 32 h. In Experiment 2, our objective was to determine whether the theca layer of an F1 follicle influenced P4 secretion by the granulosa layer of that follicle and whether such an interaction depended on the maturity of the F1 follicle (had been a F1 follicle for 8 h or 32 h). Results from Experiment 1 revealed that there was no significant difference in LH-stimulated P4 secretion by the granulosa layer in a perifusion system regardless of the length of time the follicle had been the largest follicle. In contrast, in Experiment 2, when granulosa and theca layers from the same follicle were co-incubated in a perifusion system, P4 secretion from the more mature F1 follicle (32 h) increased in response to LH, whereas P4 secretion from the less mature F1 follicle (8 h) was not elevated by LH.(ABSTRACT TRUNCATED AT 250 WORDS)     

Current utilization and further development of the palmyra palm (Borassus flabellifer L., Arecaceae) in Tamil Nadu state,India

The palmyra palm Borassus flabellifer,), a multipurpose tree of great utility, occurs extensively in Tamil Nadu state, India. Figuring in history, literature, and folklore of the state, it is exploited for food from the fruit and tuberous seedlings; beverage and sugar from the sap; fiber from the leaf and leafbase for brushes, cordage, weaving, and plaiting; trunk wood for construction and fuel; and numerous minor products. Increasing exploitation of the palmyra threatens the future supply of palm raw materials so important to rural populations. Integrated development of palmyra products for local and export markets, as well as management/conservation measures, are needed both to maximize the economic value of the products and to assure sustained yield from native stands.     

Linkage Relationships Reflecting Ancestral Tetraploidy in Salmonid Fish

Fifteen classical linkage groups were identified in two salmonid species (Salmo trutta and Salmo gairdneri) and three fertile, interspecific hybrids (S. gairdneri X Salmo clarki, Salvelinus fontinalis X Salvelinus namaycush and S. fontinalis X Salvelinus alpinus) by backcrossing multiply heterozygous individuals. These linkage relationships of electrophoretically detected, protein coding loci were highly conserved among species. The loci encoding the enzymes appeared to be randomly distributed among the salmonid chromosomes. Recombination frequencies were generally greater in females than in males. In males, certain linkage groups were pseudolinked with other linkage groups, presumably because of facultative multivalent pairing and directed disjunction of chromosomes. Five such pseudolinkage groups were identified and they also appeared to be common among species and hybrids. Duplicate loci were never classically linked with each other, although some exhibited pseudolinkage and some showed evidence of exchanging alleles. Gene-centromere recombination frequencies estimated from genotypic distributions of gynogenetic offspring were consistent with map locations inferred from female intergenic recombination frequencies. These linkage relationships support the contention that all extant salmonids arose from a common tetraploid progenitor and that this progenitor may have been a segmental allotetraploid.     

Mouse protamine 2 is synthesized as a precursor whereas mouse protamine 1 is not.

The nuclei of mouse spermatozoa contain two protamine variants, mouse protamine 1 (mP1) and mouse protamine 2 (mP2). The amino acid sequence predicted from mP1 cDNAs demonstrates that mP1 is a 50-amino-acid protein with strong homology to other mammalian P1 protamines. Nucleotide sequence analysis of independently isolated, overlapping cDNA clones indicated that mP2 is initially synthesized as a precursor protein which is subsequently processed into the spermatozoan form of mP2. The existence of the mP2 precursor was confirmed by amino acid composition and sequence analysis of the largest of a set of four basic proteins isolated from late-step spermatids whose synthesis is coincident with that of mP1. The sequence of the first 10 amino acids of this protein, mP2 precursor 1, exactly matches that predicted from the nucleotide sequence of cDNA and genomic mP2 clones. The amino acid composition of isolated mP2 precursor 1 very closely matches that predicted from the mP2 cDNA nucleotide sequence. Sequence analysis of the amino terminus of isolated mature mP2 identified the final processing point within the mP2 precursor. These studies demonstrated that mP2 is synthesized as a precursor containing 106 amino acids which is processed into the mature, 63-amino-acid form found in spermatozoa.     

Metallothionein gene expression is regulated by serum factors and activators of protein kinase C.

The exact physiological role of metallothionein (MT) is not clear. It has been suggested that these low-molecular-weight, highly inducible, heavy-metal-binding proteins serve in the regulation of intracellular Zn metabolism. Among the Zn-requiring systems are several enzymes involved in DNA replication and repair. Therefore, during periods of active DNA synthesis there is likely to be an increased demand for Zn, which could be met by elevated MT synthesis. For that reason, we examined whether stimulation of cellular proliferation leads to increased expression of MT. We report here that treatment of cultured mammalian cells with serum growth factors and activators of protein kinase C, all of which are known to have growth stimulatory activity, led to induction of MT mRNA. One of the required steps in the signal transduction pathways triggered by these agents, ending in MT induction, appears to be the activation of protein kinase C.     

Calcitonin gene-related peptide immunoreactivity in airway epithelial cells of the human fetus and infant

Summary Calcitonin gene-related peptide-immunoreactive cells were identified within the epithelium of distal conducting airways in the human fetus and infant. Several peptides and amines, including calcitonin, have been identified previously within a specific population of airway epithelial cells. These cells, referred to as pulmonary neuroendocrine cells, are postulated to be airway chemoreceptors responsible for changes in ventilation and perfusion in response to changes in airway gas composition. Calcitonin gene-related peptide immunoreactive cells could be identified throughout the period of development studies (20 weeks gestation to 3 months of age), but were present in only limited numbers in less than 50% of individuals (n=23). In contrast, large numbers of calcitonin gene-related peptide immunoreactive cells were identified in 100% of infants (1–3 months, n=5) with bronchopulmonary dysplasia. The differential processing of mRNA transcribed from the calcitonin gene in neural and non-neural tissue suggests that calcitonin, rather than calcitonin gene-related peptide, is the primary product of translation in pulmonary neuroendocrine cells. However, considering the potent vasodilatory and bronchoconstrictive effects of calcitonin gene-related peptide, its presence in pulmonary neuroendocrine cells, even in small amounts, may be important in controlling pulmonary vaso- and/or bronchomotor tone. The presence of large numbers of calcitonin gene-related peptide immunoreactive cells in infants with bronchopulmonary dysplasia suggests that calcitonin gene-related peptide may be one further agent contributing to the pulmonary pathophysiology seen in this disease.     

De novo synthesis of NGF subunits in S-180 mouse sarcoma cell line

It is an accepted hypothesis that the nerve growth factor protein (NGF) plays an important role in the development of vertebrate sympathetic and sensory ganglia and has effects on some central neurons. The best known NGF species is that isolated from the mouse submaxillary gland, MSG-NGF. MSG-NGF can be isolated as a subunit containing protein, 7S-NGF, made up of three dissimilar subunits called alpha-, beta-, and gamma-NGF. Beta-NGF is the biologically active subunit and its synthesis in vivo and in vitro has been demonstrated. Less is known about the synthesis of the alpha- and gamma-NGF or the assembly of the subunits into the 7S complex. In order to develop a clonal model system for the study of NGF synthesis, processing and secretion, affinity chromatography techniques were applied to cell extracts of S180 mouse sarcoma, a cell line known to synthesize NGF. After incubating S180 cells in³⁵S-Methionine, cell extracts were exposed to antibody directed against alpha-NGF, gamma-NGF or beta-NGF covalently bound to Sepharose beads in order to elute and characterize the desired NGF subunits. Parallel experiments using immunoabsorbed [³⁵S]Methionine-beta-NGF were carried out in the presence or absence of excess NGF, in order to demonstrate the specificity of this procedure. Affinity chromatography with a substrate analogue to arginine ester bound to Sepharose beads was also used to isolate de novo synthesized gamma-NGF. We were able to show that the S180 line synthesized alpha-, beta-, and gamma-NGF indistiguishable from alpha-, beta-, and gamma-NGF isolated from mouse submaxillary gland in terms of antigenic and physicochemical properties, and biological and enzymatic activities. These results are consistent with the hypothesis that NGF is synthesized, assembled and secreted by a single cell type.Special Issue dedicated to Dr. E. M. Shooter and Dr. S. Varon.     

An abundant, highly conserved tonoplast protein in seeds

We have isolated the membranes of the protein storage vacuoles (protein bodies) from Phaseolus vulgaris cotyledons and purified an integral membrane protein with M_r 25,000 (TP 25). Antiserum to TP 25 recognizes an abundant polypeptide in the total cell extracts of many different seeds (monocots, dicots, and a gymnosperm), and specifically labels the vacuolar membranes of thin-sectioned soybean embryonic axes and cotyledons. TP 25 was not found in the starchy endosperm of barley and wheat or the seed coats of bean but was present in all seed parts examined that consist of living cells at seed maturity. The abundance of TP 25 was not correlated with the amount of storage protein in seed tissue, and the protein was not found in leaves that accumulate leaf storage protein. On the basis of its abundance, evolutionary conservation, and distribution in the plant, we propose that TP 25 may play a role in maintaining the integrity of the tonoplast during the dehydration/rehydration sequence of seeds.     

Immediate breast reconstruction: reducing the risks

One-hundred and sixty-five consecutive immediate breast reconstructions in 157 patients were reviewed. Reconstructions were performed with tissue expanders (53 percent) or immediate gel prostheses (47 percent). Immediate reconstruction was associated with an 18 percent rate of implant loss. Certain risk factors were identified at the p less than 0.05 level using immediate gel implants: failure to achieve complete muscle coverage of the implant, smoking at the time of surgery, initial gel implants of 400 ml or more volume, and age. Expander loss was increased by detaching the pectoralis major (p less than 0.05) and probably by lack of complete muscle coverage in general. Chemotherapy, history of previous smoking, and clinical stage of the carcinoma did not seem to affect reconstructive success. Smoking and patient age should be considered during patient selection for immediate reconstruction. Muscle coverage of the prosthesis should always be attempted. Muscle coverage is mandatory in the smoker. Gel implants of 400 ml or more volume are to be avoided at the initial operation. This approach should enable all surgeons to achieve lower rates of implant loss.