Mutations in neuromusculin,a gene encoding a cell adhesion molecule,cause nervous system defects

The Drosophila neuromusculin (nrm) gene encodes an immunoglobulin-like (Ig-like) cell adhesion molecule expressed in the precursors of the embryonic peripheral nervous system (PNS), in the midline precursors of the central nervous system (CNS), and in muscles. During the initial phases of CNS axonogenesis, nrm is expressed in cells involved in the development of commissures and longitudinal tracts. Mutations which alter expression of nrm mRNAs cause aberrant development of commissures and longitudinal axon pathways. Defects in the PNS and muscles of nrm mutants are also observed. In most nrm embryos, abnormal development can be detected in a subset of abdominal segments; however, in approximately 1 of 10 nrm embryos, the defects extend to all segments. Herein, we present evidence that nrm plays an important role in early morphogenesis, possibly by mediating or facilitating inductive cell contacts and movements.     

Calcium and glucose uptake in rat small intestinal brush-border membrane vesicles. Modulation by exogenous hypercortisolism and 1.25-dihydroxyvitamin D-3

The effect of exogenous hypercortisolism and 1,25-dihydroxyvitamin D-3 on small-intestinal calcium and glucose transport in the rat was studied at the level of brush-border membrane vesicles generated from isolated villous cells by a freeze-thaw procedure. At 5 · 10^?5 M extravesicular calcium, initial uptake rates in vesicles prepared from triamcinolone-treated adult rats were decreased by 30% after 5 days. Since calcium ionophore A23187 virtually abolished the difference in calcium uptake, triamcinolone appeared to affect calcium channel density or activity rather than intravesicular binding capacity. Kinetic analysis showed that a decrease in V_max of a saturable calcium transport system could entirely account for the diminished rate of vesicular calcium uptake. Calcium transport rates could be partially restored by in vivo administration of 1,25-dihydroxyvitamin D-3 at a dosage which did not affect vesicular calcium uptake in control animals. Conversely, sodium-driven glucose accumulation in brush-border vesicles from triamcinolone-treated rats was stimulated by 50–70% after 36 h and appeared insensitive to vitamin D. A specific triamcinolone action on the glucose carrier itself rather than on the driving force of the sodium gradient was indicated by (i) a similar stimulation of glucose transport under equilibrium exchange conditions and (ii) an opposite effect of triamcinolone on sodium-driven alanine transport. The triamcinolone-induced changes in calcium and glucose uptake were not accompanied by a gross alteration of membrane integrity in vitro or by major alterations in vesicular protein composition, intravesicular glucose space and sucrase or alkaline phosphatase activity. The modification of vesicular transport properties is discussed in relation to the vitamin D-antagonized inhibition of intestinal calcium uptake and the stimulation of glucose absorption in response to supraphysiologic amounts of glucocorticoids observed in intact epithelium.     

Abdominally entrained periodicities of testis and vas deferens activity in the Mediterranean flour moth

In a light-dark (LD) regimen, sperm, first apyrene and then eupyrene, start moving out of the fused testes of the Mediterranean flour moth, Anagasta kuehniella, toward the beginning of the scotophase. At 27° ± 2°C, the sperm mass remains in the proximal part of the vasa deferentia for 10 to 12 hr and then passes rapidly into the seminal vesicles, remains in these organs for about 5 hr, and is then transported to the ductus ejaculatoris duplex where it becomes available for ejaculation. The phases of sperm movement appear to be closely related to sperm development, and the reproductive activity of the moths. In isolated abdomens there is a significant reduction in the amount of sperm released from the testes, but normal periodicity of sperm release and movement continues in either LD or continuous dark (DD) regimens, and rapid phase shifting occurs when a LD regimen is reversed. All stages of sperm movement are disrupted in continuous light (LL), but normal periodicity is usually resumed when isolated abdomens of the LL moths are placed in LD or DD regimens. Normal periodicity also occurs in moths paralyzed with tetrodotoxin or procaine. Removal of any one of the four abdominal ganglia from LL moths does not prevent increased sperm release when the moths are placed in LD, though with each ganglion there is some disruption of the normal pattern of movement down the vasa deferentia. It is thought that the testes and vasa deferentia down to at least the seminal vesicles represent a semiautonomous complex in which periodicity is maintained by endogenous circadian activity in cells of the testes (and possibly the vasa deferentia) or more probably in a peripheral control center.     

Neolignans from an Aniba species

The trunk wood of an Amazonian Aniba (Lauraceae) species contains, besides dillapiol and the benzodioxane-type neolignan eusiderin, four bicyclo(3.2.1)octanoid neolignans. These comprise representatives of the canellin-type: the known methoxycanellin-A and the novel compounds characterized as (1R, 3S, 4S, 5S, 6S, 7R)-1-allyl-4-hydroxy-3, 5-dimethoxy-7-methyl-6-(3′-methoxy-4′, 5′-methylenedioxyphenyl)-8-oxo-bicyclo(3.2.1)octane; (1R, 3S, 4S, 5S, 6S, 7R)-1-allyl-4-hydroxy-3, 5-dimethoxy-7-methyl-6-(3′, 4′, 5′-trimethoxyphenyl)-8-oxobicyclo(3.2.1)octane and (1R, 4R, 5R, 6S, 7R, 8S)-1-allyl-4, 8-dihydroxy-5-methoxy-7-methyl-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-3-oxobicyclo(3.2.1)octane.     

Mutagen-induced sister chromatid exchange rate in Bloom syndrome remains unaltered in the presence of Bloom corrective factor

Summary Fibroblasts of a patient with Bloom syndrome (GM-1492) were cultured in the presence of either mitomycin C, ethylmethanesulfonate, or 4-nitroquinoline-1-oxide, (4-NQ1-O) and sister chromatid exchange was determined. The mutagens enhanced the sister chromatid exchange rate to different degrees, 4-NQ1-O being the most potent substance. Bloom corrective factor, which is present in normal cell-conditioned culture medium, reduced the spontaneously increased SCE in Bloom syndrome cells by about 20 SCE per metaphase but failed to reduce the additional mutagen-induced SCE increase. These findings indicate that only spontaneously, but not mutagen-indeuced, SCE in Bloom syndrome fibroblasts can be decreased by the Bloom corrective factor.     

The mucus-trap hypothesis on feeding of aquatic nematodes and implications for biodegradation and sediment texture

Summary Many aquatic nematodes continuously produce with their caudal and pharyngeal glands a slimy trace consisting of sticky, elastic threads which give an acid mucopolysaccharide reaction. Along these traces small particles adhere firmly thus making the traces visible at low magnifications. By creeping repeatedly on their traces the nematodes produce burrows and solid, branched concretions in fine sediments. By these activities soft bottoms acquire a particular framework texture which perhaps may, for instance in the deep sea, enable an interstitial, non-boring microfauna to thrive.The authors suppose that the copious mucus secretion of nematodes is mainly involved in nutrition and they present an hypothesis on the assumed mode of feeding (mucus-trap hypothesis): With their mucus threads these nematodes entrap small detritus particles, bacteria, and macromolecules which subsequently are browsed together with the mucus. The combination of an adhesive mucus thread and the particular mouth construction in nematodes represents a highly elaborated collecting and sorting system for food acquisition. In addition, decomposition processes of organic material coated by the mucus may contribute to a secondary food source which is controlled by nematodes. Feces are embedded within the mucus, and their remaining nutrient content may be subjected to a later re-utilization.     

Nucleosomal distribution of thymine photodimers following far- and near-ultraviolet irradiation

The nucleosomal distribution of cis-syn cyclobutyl-type thymine photodimers was determined in normal human skin fibroblasts following irradiation with low doses of far-ultraviolet light at 254 nm and nearultraviolet light at 313 nm. The thymine photodimer concentrations were determined by high pressure liquid chromatography in acid hydrolysates of total cellular DNA and of nucleosomal core- and chromatosomal-DNA. The lesion concentrations in linker-DNA were calculated from these data. While thymine photodimers were distributed uniformely following 254 nm irradiation they were enriched by a factor of 2.4 – 4.2 in nucleosomal linker DNA after exposure to 313 nm light.     

The baboon model under anesthesia for in vivo cerebral blood flow studies using single photon emission computed tomographic (SPECT) techniques.

Single photon emission computed tomography of the brain can be useful in animal experimentation directed toward cerebral conditions. A well established and understood baboon model, necessarily under anesthesia, could be especially valuable in such investigations. Six normal baboons were studied under various anesthetic agents and their combinations: ketamine, thiopentone, pentobarbitone, and halothane. Cerebral blood flow (CBF) studies were performed with 99mTc-HMPAO. CBF effects from various anesthesia were detected, requiring careful choice of the anesthesia for cerebral investigations.