The hormonal responses to repetitive brief maximal exercise in humans

The responses of nine men and nine women to brief repetitive maximal exercise have been studied. The exercise involved a 6-s sprint on a non-motorised treadmill repeated 10 times with 30 s recovery between each sprint. The total work done during the ten sprints was 37,693 +/- 3,956 J by the men and 26,555 +/- 4,589 J by the women (M greater than F, P less than 0.01). This difference in performance was not associated with higher blood lactate concentrations in the men (13.96 +/- 1.70 mmol.l-1) than the women (13.09 +/- 3.04 mmol.l-1). An 18-fold increase in plasma adrenaline (AD) occurred with the peak concentration observed after five sprints. The peak AD concentration in the men was larger than that seen in the women (9.2 +/- 7.3 and 3.7 +/- 2.4 nmol.l-1 respectively, P less than 0.05). The maximum noradrenaline (NA) concentration occurred after ten sprints in the men (31.6 +/- 10.9 nmol.l-1) and after five sprints in the women (27.4 +/- 20.8 nmol.l-1). Plasma cardiodilatin (CDN) and atrial natriuretic peptide (ANP) concentrations were elevated in response to the exercise. The peak ANP concentration occurred immediately post-exercise and the response of the women (10.8 +/- 4.5 pmol.l-1) was greater than that of the men (5.1 +/- 2.6 pmol.l-1, P less than 0.05). The peak CDN concentrations were 163 +/- 61 pmol.l-1 for the women and 135 +/- 61 pmol.l-1 for the men. No increases in calcitonin gene related peptide (CGRP) were detected in response to the exercise. These results indicate differences between men and women in performance and hormonal responses. There was no evidence for a role of CGRP in the control of the cardiovascular system after brief intermittent maximal exercise.     

Rod opsin cDNA sequence from the sand goby (Pomatoschistus minutus) compared with those of other vertebrates.

The absorbance spectra of rods from the sand goby were measured by using microspectrophotometry. Analysis of the averaged spectra shows that the rod visual pigment has a maximum absorbance (lambda max) at approximately 501 nm. A sand goby retinal cDNA library was constructed and then screened with a partial sand goby rod opsin clone obtained by the polymerase chain reaction (PCR). The screening of the library yielded a full length rod opsin clone. The cDNA sequence and deduced amino acid sequence of this clone are compared with those of other vertebrate rod opsins.     

Activation of a cryptic gene by excision of a DNA fragment.

The cryptic bgl operon in Escherichia coli K-12 strain 1011A contains a 1.4-kilobase-pair fragment of foreign DNA within the bglF structural gene. The active allele found in its descendant strain, MK1, required the precise excision of that insertion for its activation. Molecular and genetic approaches have shown that strain 1011A possessed an active (bglR+) rather than a silent wild-type (bglR0) allele of the regulatory region and that this change was caused by a point mutation. Our model for the retention of cryptic genes (B. G. Hall, S. Yokoyama, and D. H. Calhoun, Mol. Biol. Evol. 1:109-124, 1983) suggested that the insertion might have been selected to silence a disadvantageous bglR+ allele. We examined the genealogy of strain MK1 and found that the insertion of foreign DNA was not selected for that reason, since it preceded the change to bglR+. This means that the change to bglR+ was also not selected, since the presence of the insertion would not allow expression of the operon. We have calculated the probability of isolating a bglR+ mutation by chance alone as less than 10(-8). We suggest that mutation rates estimated under the usual conditions of exponential growth may be irrelevant to the frequencies of these events under natural conditions.     

In nondividing cells, histone H1(0) is synthesized and deposited onto chromatin without accompanying phosphorylation

The phosphorylation of H1 histone subfractions was measured in mouse neuroblastoma cells stopped from dividing by three treatments that block cell division: 5 mM butyrate, 2% dimethyl sulfoxide, and serum withdrawal. H1 histone phosphorylation decreased in response to all three treatments, but the response differed in its timing and its extent for the different H 1 subfractions. The different decreases in phosphorylation correlated well with the differential decreases in biosynthesis of the individual H1 subfractions; however, an exception to this parallel decrease in synthesis and phosphorylation was observed in the case of histone H1(0). Phosphorylation of H1(0) was absent in each of the three treatments after 2 days, despite the continued synthesis and deposit of H1(0) on the chromatin. Thus, despite the fact that H1(0) was being synthesized and that the other newly synthesized H1 subfractions were phosphorylated at this time, the phosphorylation of H1(0) became uncoupled from its synthesis after prolonged treatments blocking cell division.     

Sutural morphogenesis in the mouse calvaria: the role of apoptosis

Sutural morphogenesis was studied in calvariae of fetal and newborn 16- to 26-day postconception C57B1/6J mice. The squamoid pattern characteristic of most calvarial sutures appeared to be established during the phase of approach of the adjacent bone territories as they assumed different ecto/ifendocranial planes within the desmocranium. When this stratification failed, apoptosis, a form of cell death, was seen to occur upon physical contact of the leading osteogenic cells of each heterotopic bone territory. Apoptosis appeared as part of a secondary morphogenetic mechanism preventing physical contact and resultant fusion of adjacent mineralized zones, as well as enhancing appearance of the usual pattern of overlap of calvarial sutures.     

Rationalization of some genetic anticodonic assignments

The genetic code appears to be a logic matrix in which, generally speaking, there is a correlation between the hydrophobicities of amino acids and their anticodonic nucleotides. There are several exceptions to this generality, however, and using previous data on hydrophobicity and binding constants, coupled with new data on reaction rates, we rationalize several of the anticodonic assignments.     

Transient enhancement of serum somatomedin levels prior to weaning of growth-impaired vasopressin-deficient Brattleboro rats

Somatomedin serum levels of congenitally vasopressin-deficient Brattleboro rats were determined postnatally between day 1 and 55, and compared with heterozygous control values. Assays were performed with a radioimmunoassay of insulin-like growth factor 1 (IGF-1). A transient enhancement of immunoreactive IGF-1 levels between day 8 and 21 of age and a reduction in adulthood was found. This observation shows that the early growth impairments of the Brattleboro mutant are not due to a deficiency of IGF-1.     

Plasma esterase polymorphism in the Bank vole, Clethrionomys glareolus, in Britain

Three hundred and eighty-three Clethrionomys glareolus from 20 localities in England, Wales and Scotland were typed for plasma esterase and a genetic polymorphism was discovered. The esterase was named Es-1. Breeding tests suggested that three alleles were segregating: Es-1^o when homozygous results in complete absence of enzyme activity. The active alleles Es-1^f and Es-1^s code for enzyme variants which migrate more rapidly and less rapidly, respectively, under starch gel electrophoresis. Of these active alleles, Es-1^f is morc common in the north of Britain and Es-1⁸ in the south. A 23-month field study on two areas at Wicken Fen, Cambridgeshire, suggested that animals possessing Es-1^s survived less well at high population densities, perhaps through their being more likely to emigrate.