The relationship between plasma progesterone and the timing of ovulation and early embryonic development in the marmoset monkey (Callithrix jacchus)

Levels of progesterone in peripheral plasma samples showed a mean (± S.E.M.) ovarian cycle length of 28 ·63 ± 1·01 days ( n = 19).
The preovulatory, or follicular phase (mean ± S.E.M. length: 8·25 ± 0·30 days, n = 56) was defined as that period of the cycle during which progesterone levels remained below 10 ng/ml. The postovulatory, or luteal phase (mean ± S.E.M. length: 19·22 ± 0·63 days, n = 48) was defined as the remaining period of the cycle during which levels remained between 10 ng/ml and 150 ng/ml.
The day of ovulation (day 0) was defined as that preceding the day on which progesterone levels first exceeded 10 ng/ml (day l), at the onset of the luteal phase. Oocytes and preim-plantation embryos recovered from the reproductive tract provided supporting evidence for the timing of ovulation.
The short follicular phase indicated that follicular growth may be initiated during the previous luteal phase. The long luteal phase may be related to the extended period of preim-plantation development.     

Ultrastructural localization of the high molecular weight proteins associated with in vitro-assembled brain microtubules

Microtubules isolated from brain extracts by in vitro assembly (1, 19, 23) are composed principally of two tubulins and two high molecular weight proteins (microtubule-associated proteins [MAPS] 1 and 2) (2,5,7,20). Recently, it was demonstrated that in vitro-assembled brain microtubules (neurotubules) are coated with filaments (5, 7) which are similar to the filaments attached to neurotubules in situ (4, 15, 21, 24, 25), and it was suggested that the filaments are composed of the higher molecular weight MAPs (5, 7, 12). In this study, microtubules were assembled in the presence and absence of the MAPs, and thin sections of the microtubules were examined by electron microscopy. The results show that the filaments only occur on microtubules assembled in the presence of the MAPs and it is therefore concluded that the filaments are composed of the high molecular weight MAP's.     

Electron microscopic localization of chromogranin A in osmium-fixed neuroendocrine cells with a protein A-gold technique

An antibody (LK2H10) to chromogranin A has been recommended for use in ultrastructural identification of neuroendocrine secretory granules. Previous studies have demonstrated immunoreactive chromogranin A in specimens prepared for electron microscopy by glutaraldehyde fixation only. In this study, the effect of specimen post-fixation by osmium tetroxide on post-embedding localization of chromogranin A was evaluated. Human tissues from benign endocrine glands, neuroendocrine tumors, and non-neuroendocrine tumors were post-fixed in osmium, embedded in epoxy resin, and the sample thin sections immunolabeled using a protein A-gold technique. Chromogranin A-positive neurosecretory granules were detected in pancreatic islets, adrenal medulla, stomach, ileum, anterior pituitary, and parathyroid. Mid-gut carcinoids, bronchial carcinoids, pheochromocytomas, paragangliomas, carotid body tumors, and thyroid medullary carcinomas contained immunoreactive granules. Cytoplasmic granules in non-neuroendocrine tumors did not react for chromogranin A. Tissues post-fixed in osmium tetroxide had optimally preserved ultrastructural features, and use of this fixative is compatible with postembedding localization of chromogranin A in neurosecretory granules.     

A proton-nuclear-magnetic-resonance study of human somatotropin (growth hormone). Assignment and properties of the histidine residues.

The 1H-n.m.r. spectra of human somatotropin (growth hormone) show perturbed peaks from individual aromatic and aliphatic apolar residues, characteristic of a specifically folded globular structure. The imidazole C-2-H resonances of the histidine residues (at positions 18, 21 and 151 in the somatotropin sequence) were individually resolved, and their titration behaviour in the pH range 1.2-11.5 was investigated. The imidazole C-2-H resonance of histidine-151 is assigned, by comparison of its titration behaviour in human somatotropin and desamido-somatotropin (Asn-152 leads to Asp-152). The C-2-H resonances of all three histidine residues are assigned, by comparison of their relative deuterium-exchange rates (determined by n.m.r.) and the relative tritium-exchange rates of the histidine residues (determined by tryptic digestion of tritiated human somatotropin and reversed-phase high-pressure liquid-chromatographic separation of the histidine-containing tryptic peptides). There is evidence that histidine-18 forms an ion-pair bond with a glutamic acid or aspartic acid residue. The globular structure does not appear to change from pH3 to 11.5, though there is evidence for an unfolding of a region of the structure (involving histidine-21 and a tyrosine residue) below pH3.     

The preparation and partial characterization of antigenic fractions obtained from the mycelial walls of several Aspergillus species

Extracts with immunological activity were prepared from Aspergillus fumigatus, A. flavus, A. terreus, A. niger and A. nidulans. In each case crude mycelial wall was extracted with an aqueous solution of Triton X-100 giving detergent-soluble material. Further fractionation was achieved by removing the detergent from this solution; the resultant precipitate was removed by centrifugation, and the aqueous supernatant was used as a source of soluble antigens. The sensitivity of these preparations was compared with that of water-soluble antigenic material, prepared from whole macerated mycelium, by double diffusion and counterimmunoelectrophoresis using homologous antisera and sera from patients suffering from aspergilloma and allergic bronchopulmonary aspergillosis. The selectivity of these antigenic preparations was monitored with heterologous antisera raised in rabbits. Batch variability was analysed for one strain of A. fumigatus using chemical and immunological methods. The nature of the antigenic sites involved in these reactions was investigated by studying the susceptibility of the preparations to proteolytic hydrolysis, periodate oxidation and concanavalin A treatment. The total protein and carbohydrate content of each fraction was determined and the constituent sugars analysed in an attempt to correlate chemical composition with antigenic activity.     

Chorionic gonadotrophin and embryo-maternal recognition during the peri-implantation period in primates

Genes for chorionic gonadotrophin (CG) are transcribed by the 16-cell embryo stage in humans, but there is no clear evidence of CG secretion as a bioactive dimer before attachment and trophoblast outgrowth stages of implantation. The studies summarized question the timing of CG expression and secretion, the possible roles of CG for intraembryonic differentiation and at the implantation site, and the recognition of this primate embryo-derived signal in support of the corpus luteum. The data suggest that the implantation window in primates may be broader than in non-primate species, where a closer synchrony between embryonic, tubal and uterine events appears to be necessary for embryonic survival. Some preliminary data concerning an association between peripheral thrombocytopenia, ovarian inhibin secretion and peri-implantation stages of embryo development indicate that an unknown embryonic signal may be secreted before bioactive CG can be detected.     

Duchenne muscular dystrophy and dystrophin: Sequence homology observations

Duchenne muscular dystrophy (DMD) is a genetically transmitted disease characterized by progressive muscle weakness and usually leads to death. DMD results from the absence, deficiency or dysfunction of the protein dystrophin. Analysis of protein data bases, including homology alignments and domain recognition patterns, have located highly significant correlations between dystrophin and other calcium regulating proteins. In particular, a major portion of the dystrophin sequence has been found to contain repeating units of approximately 100 amino acid residues. These repeating units were found to exhibit significant homology to troponin I. Troponin I has been found to bind to the calcium binding proteins calmodulin and troponin C. The regions of highest homology were characterized by patterns of high localization of charged amino acids and thus could represent a possible calmodulin or troponin C surface accessible binding site. Since subcellular localization studies have indicated that dystrophin is associated with the triadic junction, these findings imply that dystrophin could be involved in controlling intracellular calcium homeostasis.Special issue dedicated to Dr. Lawrence Austin.     

Guardians of Culture: The Controversial Heritage of Senegalese Griots1

The low‐caste Griots of Senegal's Wolof community, traditionally employed as singers of histories and praises, earn their keep today by playing sabar drums at private women's dance parties. Although these gatherings are publicly scorned for the sexually expressive dances they involve, they are nevertheless immensely popular behind closed doors. Many Griot drummers justify their participation in sabar performances by linking the activity with the work of their historically marginalised ancestors, though this connection is disputed by elderly Griots, who view it as departure from their occupational tradition. While sabar is criticised for subverting both Griot heritage and public standards of decency, the ethnographic data suggest that it nevertheless reproduces traditional patronage relationships based on the interdependence and mutual benefit of the low‐status (caste) and high‐status (noble) sectors. Research is based on eleven months of participant observation in Senegal in 1996 and 1997, during which time the author trained as a sabar drummer in Dakar and Saint‐Louis.