Scanning and transmission electron microscopy evidence of the cytological effect of pyrrolnitrin on ‘Microsporon audouinii’ Gruby CBS 313-54 ‘in vitro’

Scanning and transmission electron microscopy showed that a ceiling quantity (1.56 mcg) of antifungal antibiotic Pyrrolnitrin caused heavy damage to dermathophyteMicrosporon audouinii Gruby CBS 313-54in vitro. Suitable preparation technique made it clear that the changes involved consisted of hyphal collapse on the edge of the culture, with loss of euplasmic organelles identity and cell autolysis. The cell wall, however, was apparently undamaged. These findings fit in with the suggestion that the mode of action of the antibiotic leads to generalised lipoproteic membranes damage. They must, however, be considered as representing the result of the terminal phase of cell distress.     

Synteny on mouse chromosome 5 of homologs for human DNA loci linked to the Huntington disease gene

Comparative mapping in man and mouse has revealed frequent conservation of chromosomal segments, offering a potential approach to human disease genes via their murine homologs. Using DNA markers near the Huntington disease gene on the short arm of chromosome 4, we defined a conserved linkage group on mouse chromosome 5. Linkage analyses using recombinant inbred strains, a standard outcross, and an interspecific backcross were used to assign homologs for five human loci, D4S43, D4S62, QDPR, D4S76, and D4S80, to chromosome 5 and to determine their relationships with previously mapped markers for this autosome. The relative order of the conserved loci was preserved in a linkage group that spanned 13% recombination in the interspecific backcross analysis. The most proximal of the conserved markers on the mouse map, D4S43h, showed no recombination with Emv-1, an endogenous ecotropic virus, in 84 outcross progeny and 19 recombinant inbred strains. Hx, a dominant mutation that causes deformities in limb development, maps approximately 2 cM proximal to Emv-1. Since the human D4S43 locus is less than 1 cM proximal to HD near the telomere of chromosome 4, the murine counterpart of the HD gene might lie between Hx and Emv-1 or D4S43h. Cloning of the region between these markers could generate new probes for conserved human sequences in the vicinity of the HD gene or possibly candidates for the murine counterpart of this human disease locus.     

The cardiac actin locus (Actc-1) is not on mouse chromosome 17 but is linked to beta 2-microglobulin on chromosome 2

A restriction fragment variant and recombinant inbred strains were used to show that the cardiac actin locus (Actc-1) is closely linked to beta 2-microglobulin (B2m) and several other loci on chromosome 2 of the mouse. Close linkage of Actc-1 and B2m in both man and mouse provides another example of a chromosomal segment that has been conserved since the divergence of the lineages leading to these two species.     

Pulsed-field gel analysis of human immunoglobulin heavy-chain constant region gene deletions reveals the extent of unmapped regions within the locus

The human immunoglobulin heavy-chain constant region gene locus is organized in three main gene groups, the physical distances of which are unknown. Different types of gene deletions, originated by unequal crossingover, have been found to encompass one or more genes in the locus. We have analyzed some of these deletions by means of pulsed-field gel electrophoresis, which allows resolution of large DNA fragments. By identifying a fragment containing two of the main gene groups and by observing the size reduction of this fragment in subjects with deletions, we were able to estimate the distance between the two groups and better locate the pseudogene in-between.     

Oestrogens down-regulate type I but not type II adrenal corticoid receptors in rat anterior pituitary

We have studied type I and type II adrenal cortical steroid receptors in the anterior (AL), intermediate (IL) and posterior (PL) lobes of the pituitary and in the hippocampus of ovariectomized-adrenalectomized female rats and in castrated-adrenalectomized male animals, with or without oestrogen treatment. Using [3H]dexamethasone as ligand and conditions suitable for determination of its binding to type I and type II receptors, we found that 4 or 15 days of oestrogen reduced type I receptors in AL by 50-60% without changes in IL, PL or hippocampus, or in type II sites in any of the four neuroendocrine tissues studied. This down-regulatory effect was seen only in female rats and no change was found for males. The reduction in type I sites in AL in oestrogenized female rats was confirmed by labelling type I sites with the synthetic antimineralocorticoid [3H]ZK 91587. Saturation analysis with [3H]ZK 91587 demonstrated that the reduction was due to a reduction in Bmax without change in Kd. We conclude that: (a) type I receptors in the anterior pituitary are under oestrogenic control; (b) there is a sex difference in the response to oestrogen of AL type I sites; and (c) this demonstration may be useful in determining the role of type I receptors in neuroendocrine regulation of the anterior pituitary by hormones derived from the adrenal cortex, and the participation of sex hormones in this process.     

Internal desynchronization of circadian rhythms and tolerance of shift work

Fifteen male subjects including 12 shift workers (oil refinery operators) volunteered to document circadian rhythms in sleep-wake, grip strength of both hands, peak expiratory flow, heart rate, self-rated drowsiness, fatigue and attention. Each of these variables was measured 4 to 6 times/day for 2 to 3 weeks. In addition, both axillary temperature (with a shielded probe) and wrist activity were almost continuously recorded at 15 min intervals during the same time span. Individual time series were analyzed according to several statistical methods (power spectrum, cosinor, chi 2, etc.), in order to estimate the prominent circadian period tau and to evaluate both individual and subgroup differences with regard to tolerance of shift work, age, duration of shift work. The present study confirms for continuously recorded temperature and wrist activity, grip strength of both hands, heart rate and peak expiratory flow that intolerance of shift work is frequently associated with an internal desynchronization. However, this conclusion cannot be extended to circadian rhythms in self-rated drowsiness, fatigue and attention. The internal desynchronization among several circadian rhythms supports the hypothesis that these latter are driven by several oscillators, with presumable differences between right and left hemispheres as suggested by unequal values of tau in rhythms of both hand grip strength. Since an internal desynchronization can be observed in tolerant shift workers having no complaint, it is likely that symptoms of intolerance are related to the subject's sensitivity to internal desynchronization rather than to the desynchronization itself.