Isolation and characterization of a highly polymorphic human locus (DXS455) in proximal Xq28

Human Xq28 is highly gene dense with over 27 loci. Because most of these genes have been mapped by linkage to polymorphic loci, only one of which (DXS52) is informative in most families, a search was conducted for new, highly polymorphic Xq28 markers. From a cosmid library constructed using a somatic cell hybrid containing human Xq27.3----qter as the sole human DNA, a human-insert cosmid (c346) was identified and found to reveal variation on Southern blot analyses with female DNA digested with any of several different restriction endonucleases. Two subclones of c346, p346.8 and p346.T, that respectively identify a multiallelic VNTR locus and a frequent two-allele TaqI polymorphism were isolated. Examination of 21 unrelated females showed heterozygosity of 76 and 57%, respectively. These two markers appeared to be in linkage equilibrium, and a combined analysis revealed heterozygosity in 91% of unrelated females. Families segregating the fragile X syndrome with key Xq28 crossovers position this locus (designated DXS455) between the proximal Xq28 locus DXS296 (VK21) and the more distal locus DXS374 (1A1), which is proximal to DXS52. DXS455 is therefore the most polymorphic locus identified in Xq28 and will be useful in the genetic analysis of this gene dense region, including the diagnosis of nearby genetic disease loci by linkage.     

Chromosome banding and genome compartmentalization in fishes

The diploid chromosome number of the Chinese raccoon dog varies from 54 (no B chromosomes) to 58 (4 B chromosomes). The B chromosomes are totally heterochromatic. An electron microscopic study was made of the synaptonemal complexes (SC) in spermatocytes of these animals. The SC karyotype consists of 27 regular chromosome pairs (autosomes and the sex chromosomes) plus the B chromosomes. The Bs pair effectively with one another at pachytene, but the SC axes of the B chromosomes are much denser than those of the A chromosomes. Depending on the number of Bs, both bivalents and multivalents have been observed. When three B chromosomes are present in a cell, parallel alignment of all three SCs can be seen. Formation of multivalents indicates high homology among these supernumerary heterochromatic chromosomes. Fusiform bulges are found along unpaired regions of all chromosomes which are particularly pronounced in diplotene.     

Studies on the Bohr Effect of Sheep Hemoglobin

A simple method is described for the measurement of pH changes in hemoglobin solutions on oxygenation and reduction. Data are presented establishing the absence of a Bohr effect in p-chloromercuribenzoate [PCMB] treated hemoglobin. The influence of a number of sulfhydryl inhibitors on the Bohr effect of a hemoglobin solution is reported and an interpretation based on steric factors in the protein is proposed.     

A new enzymatic route to the synthesis of 12-ketoursodeoxycholic acid

Summary Cholic acid (3,7,12-trihydroxy-5-cholanoic acid) was completely and selectively transformed into 12-ketoursodeoxycholic acid (3,7-dihydroxy-12-oxo-5-cholanoic acid) by means of two consecutive enzymatic steps catalyzed, the first, by 7- and 12-hydroxysteroid dehydrogenase and, the second, by 7-hydroxysteroid dehydrogenase. Coenzyme regeneration was carried out with -ketoglutarate-glutamate dehydrogenase and glucose-glucose dehydrogenase, respectively.     

Distribution patterns of the paraneuronal endocrine cells in the skin, gills and the airways of fishes as determined by immunohistochemical and histological methods

Summary The neuro-endocrine cells of fish skin and respiratory surfaces, and their bioactive secretion as far as is known, are reviewed, and compared with similar elements in tetrapods, particularly amphibians. In the skin of teleost fish, immunohistochemistry has shown that Merkel cells react for serotonin, neuron-specific enolase and enkephalins. The pharmacology is not established in dipnoans or lampreys. In some teleosts, neuromasts react for substance P and leu-enkephalins; substance P is also reported from some ampullary organs (electroreceptors). Taste buds of teleosts may react for enkephalin and substance P. Basal cells of taste buds react for serotonin and neuron-specific enolase. Some unicellular skin glands of teleosts express bioactive compounds, including serotonin and some peptides; this ectopic expression is paralleled in amphibian skin glands. The dipnoan Protopterus has innervated pulmonary neuro-endocrine cells in the pneumatic duct region with dense-cored vesicles. In Polypterus and Amia the lungs have serotonin-positive neuro-endocrine cells that are apparently not innervated. In fish gills, a closed type of neuro-endocrine cell reacts for serotonin, an open type for enkephalins and some calcium-binding proteins (calbindin, calmodulin and S-100 protein). The functions of neuro-endocrine cells in fishes await investigation, but it is assumed they are regulatory.     

Vasoactive Intestinal Peptide and Forskolin Stimulate Interleukin 6 Production by Rat Cortical Astrocytes in Culture via a Cyclic AMP-Dependent, Prostaglandin-Independent Mechanism

Abstract: In this study we analyzed the involvement of the cyclic AMP (cAMP)-protein kinase A system in the regulation of interleukin 6 production by cultured cortical astrocytes. Vasoactive intestinal peptide strongly increased, in a dose-dependent manner, interleukin 6 production. This effect was reduced when protein kinase A was blocked by KT-5720; it was not affected by calphostin C, a protein kinase C inhibitor. Forskolin caused a concentration-dependent increase in interleukin 6 release that was also inhibited by KT-5720. Because prostaglandins are believed to play a role in interleukin 6 production, we tried to determine whether the stimulatory effects of vasoactive intestinal peptide and forskolin on cytokine release might be mediated by stimulation of prostaglandin production in cortical astrocytes. Vasoactive intestinal peptide did not increase the production of either prostaglandin E₂ or F_2α. Conversely, forskolin concentration-dependently stimulated the production of both prostaglandins, an effect that was blocked by indomethacin. Indomethacin did not affect either vasoactive intestinal peptide- or forskolin-stimulated interleukin 6 production. To exclude the possibility that prostaglandins participate in interleukin 6 production induced by forskolin, we tested prostaglandins E₂ and F_2α. The former was completely ineffective in eliciting the cytokine production, whereas prostaglandin F_2α slightly increased interleukin 6 production only at the highest concentrations. 8-Bromo-cAMP and dibutyryl-cAMP stimulated interleukin 6 production to a lesser extent than vasoactive intestinal peptide and forskolin. In conclusion, we provide evidence that vasoactive intestinal peptide increases interleukin 6 production by astrocytes through the stimulation of the cAMP-protein kinase A pathway, an effect that is reproduced by cAMP analogues. In addition, we point out that prostaglandins are not involved in vasoactive intestinal peptide- and forskolin-mediated induction of interleukin 6 production in cultured astrocytes.     

Rhythmical timing and spatial scattering of foraging in a homer limpet {Patella rustica)

Homing to a more or less permanent scar after each foragingexcursion is a common movement pattern among intertidal gastropodsand chitons; however, details of the timing and spacing of foragingactivity have been investigated only in a few species. The presentstudy analyzes the short-term behavior of the limpet Patellarustica along the Tyrrhenian coast, Italy, using a motographictechnique to assess the fine organization of its foraging duringfavorable periods of sea roughness. P. rustica becomes activeonce the upper midlittoral is well splashed. It alternates foragingexcursions and resting at home with a periodicity slightly longerthan 12 h, suggesting a tidal-diel pattern. However, periodogramanalysis of the sea level oscillations during the study periodsrevealed no such rhythmicity because tidal oscillations werehidden by irregular variations caused by waves. As a resultof this time partitioning, limpets move, on average, less than50% of their potential activity time. Time partitioning maybe highly adaptive in reducing potential risks. Nevertheless,in the absence of clear external driving cues, the significanceof a very regular and apparently tidal pattern, fairly synchronousamong the different specimens, remains to be explained. Theactivity of P. rustica during each excursion is organized intothree parts: the outgoing journey during which grazing activityprogressively increases, a central part characterized by intensegrazing, and the return characterized by fast displacement anda more or less consistent trail following. Limpets head forrandom directions to reach foraging grounds in successive excursions,showing only a slight avoidance of the direction taken duringthe previous outward journey. This pattern produces a spatialscattering of grazing activity, allowing efficient exploitationof grazing areas distributed radially around home during subsequentexcursions.     

Effect of acetyl-l-carnitine on lipid peroxidation and xanthine oxidase activity in rat skeletal muscle

It has been reported that acetyl-l-carnitine (AcCn) can reduce the degenerative processes in the central nervous system of rats, modify the fluidity of membranes and decrease the accumulation of lipofuscins in neurones. In light of these considerations we have assayed the in vitro effect of acetyl-l-carnitine on spontaneous and induced lipoperoxidation in rat skeletal muscle; in addition, the effect of AcCn on XD/XO ratio was evaluated. The presence of AcCn (10–40 mM) in incubation medium significantly reduced MDA and conjugated diene formation in rat skeletal muscle; moreover, a significant decrease in induced MDA levels was observed when microsomal preparation where incubated in the presence of 10–40 mM AcCn. Since a significant reduction of XO activity was detected in the presence of 10–80 mM AcCn, the reduced lipid peroxidation by AcCn seems to be due to an inhibition of XO activity.     

The relationships between brain, serum, and whole blood ChE activity in the wood mouse (Apodemus sylvaticus) and the common shrew (Sorex araneus) after acute sublethal exposure to dimethoate

Inhibition of cholinesterase (ChE) activity produced by a single acute intraperitoneal administration of dimethoate was studied in the wood mouse, Apodemus sylvaticus, and the common shrew, Sorex araneus, under laboratory conditions. ChE values from serum and whole blood were compared with those obtained from brain in order to obtain a non-destructive tool for predicting the severity of brain acetylcholinesterase (AChE) inhibition. In addition, serum and brain inhibition following oral exposure to dimethoate was also measured in the wood mouse. Normal ChE activity was higher in the brain and whole blood of the shrews than in wood mice. There was no difference between species in serum ChE activity. Exposure to dimethoate caused a dose-dependent reduction in ChE activity and there was a significant recovery in activity with increasing time after administration. In both species, serum and whole blood were more sensitive than brain for revealing organophosphate-induced ChE inhibition and serum was more sensitive than whole blood. Statistically significant relationships were defined between whole blood and brain ChE activity and between serum and brain ChE activity. Compared with serum, whole blood ChE activity was the more accurate predictor of brain AChE levels. The relationships between brain and serum ChE activity did not appear to be affected by the route of administration of the pesticide.