Early effects of 1,25 dihydroxyvitamin D on bone calcium in vitamin D-deficient rats

The early effects of 1,25 dihydroxyvitamin D [1,25 (OH)2D] on calcium transfer in and out of the skeleton were studied in rats to determine whether mobilized bone calcium was reutilized during new bone mineralization. Vitamin-D deficient rats were labeled with 45calcium 10 to 14 days prior to treatment (experiment 1) or at the same time (experiment 2) they were injected with 0.125 microgram of 1,25 (OH)2D. Blood and bone samples were collected from 30 min to 24 h following 1,25 (OH)2D injection. Stable and radioactive calcium were determined in serum, and caudal vertebrae were subjected to histomorphometric and autoradiographic studies. In the rats of experiment 1, serum specific radioactivity peaked from 1 to 3 h after 1,25 (OH)2D injection, while there was no change in control rats receiving the vehicle alone. In the untreated vitamin D-deficient rats of experiment 2, the rate of 45calcium loss in serum was higher than normal but returned to normal after 1,25 (OH)2D injection. Serum calcium and osteoclast number remained initially unchanged, suggesting that 1,25 (OH)2D acted by increasing the efflux of calcium from bone and/or by stimulating the activity of existing osteoclasts. The rapid mobilization of 45calcium, accompanied by an increase in the extent of actively mineralizing surfaces, was followed by an increase in the extent of endosteal surface with osteoblasts and by specific incorporation of radioactive calcium at sites of new bone calcification. This study indicates that in vitamin D-deficient rats, the initial promotion of bone mineralization by 1,25 (OH)2D resulted in part from the rapid mobilization of calcium from old mineralized bone.     

Brain endocast asymmetry in pongids and hominids: Some preliminary findings on the paleontology of cerebral dominance

Observations on petalial asymmetry for 190 hominoid endocasts are reported, and their statistical differences assessed. While all taxa of hominoids show asymmetries to various degrees, the patterns or combinations of petalial asymmetries are very different, with fossil hominids and modern Homo sapiens showing an identical pattern of left-occipital, right-frontal petalias, which contrasts with those found normally in pongids. Of the pongids, Gorilla shows the greater degree of asymmetry in left-occipital petalias. Only modern Homo and hominids (Australopithecus, Homo erectus, Neandertals) show a distinct left-occipital, right-frontal petalial pattern. Analysis by x² statistics shows the differences to be highly significant. Due to small sample size and incompleteness of endocasts, small-brained hominids, i.e., Australopithecus, are problematical. To the degree that gross petalial patterns are correlated with cognitive task specialization, we speculate that human cognitive patterns evolved early in hominid evolution and were related to selection pressures operating on both symbolic and spatiovisual integration, and that these faculties are corroborated in the archaeological record.     

The preparation of biotinyl-epsilon-aminocaproylated forms of the vasoactive intestinal polypeptide (VIP) as probes for the VIP receptor.

Vasoactive intestinal polypeptide (VIP) was biotinyl-epsilon-aminocaproylated using sulfosuccinimidyl-6-(biotinamido) hexanoate thereby producing a series of products that were separated by high performance liquid chromatography (HPLC). Seven VIP-derivatives were isolated and the number and location of biotinyl-epsilon-aminocaproylation was determined by a combination of enzymatic degradation and plasma desorption mass spectrometry (PDMS). Receptor binding experiments with the VIP biotinyl-epsilon-aminocaproylated derivatives revealed IC50 values for the monobiotinyl-epsilon-aminocaproylated peptides that were 1.3-3.2 times higher than for natural VIP. All isolated biotinyl-epsilon-aminocaproylated derivatives possess VIP-like bioactivity as shown by an assay measuring pancreatic juice secretion in cat, VIP biotinyl-epsilon-aminocaproylated in position lysine being almost equipotent with natural VIP.     

Genomic Effects of Cold and Isolation Stress on Magnocellular Vasopressin mRNA-Containing Cells in the Hypothalamus of the Rat

We assessed the effects of cold and isolation stress on arginine vasopressin (AVP) mRNA in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. Vasopressin mRNA levels were determined by in situ hybridization histochemistry at the cellular level. In posterior magnocellular neurons of the PVN isolation stress for 7 or 14 days increased vasopressin mRNA levels 28 and 29%, respectively, compared to group-housed controls. No significant alterations in vasopressin gene expression were observed in the SON after 7 or 14 days of isolation stress. Scattered magnocellular AVP mRNA-expressing cells of the medial parvocellular PVN showed increases of 19 and 34% after 7 and 14 days of isolation, respectively. We also studied the effect of cold or combined cold and isolation stress on vasopressin gene expression in the PVN and SON. Cold stress for 3 h daily for 4 consecutive days increased AVP mRNA levels in the posterior magnocellular PVN by 15%. Cold-isolated animals showed an increase of 21%. No significant effect on AVP mRNA levels in the SON was observed. In contrast to the posterior magnocellular PVN, cold or cold-isolation stress increased AVP mRNA in magnocellular neurons of the medial parvocellular region of the PVN by 25 and 43%, respectively, relative to control rats. These results suggest that psychological and metabolic stress may be added to the list of stressors that activate the hypothalamo-neurohypophysial system.     

Urinary but Not Brain Isatin Levels Are Reduced in Germ-Free Rats

Germ-free rats excreted considerably smaller amounts of the monoamine oxidase-inhibiting compound isatin than the substantially larger output by conventional animals of the same strain, although concentrations in brain and other tissues were similar in the two groups. Thus, isatin is likely to be elaborated both endogenously in rat tissues and "exogenously" by flora inhabiting the lumen of the alimentary tract.     

A partially deficient mutant, recA1730, that fails to form normal nucleoprotein filaments.

Summary The phenotype of the recA1730 mutant is highly dependent on the level of expression of the RecA1730 protein. If the recA1730 gene was expressed from its own promoter, the cells were deficient in recombination and SOS induction. In contrast, when the recA1730 gene was expressed under the control of recAo98, a constitutive operator that increased the RecA1730 concentration 20-fold, cells became proficient in recombination and SOS induction. Likewise, in crude extracts, fivefold more RecA1730 than RecAwt was required to produce full cleavage of LexA protein. The requirement for a high RecA1730 concentration for recombination and LexA cleavage suggests that the recA1730 defect alters a common reaction step. In fact, in vitro data show that the impaired assembly of RecA1730 protein on single-stranded DNA (ssDNA) can account for the mutant phenotype. Purified RecA1730 protein was assayed in vitro for ssDNA binding and ATPase activities. RecA1730, like RecAwt, retained ssDNA equally well on nitrocellulose filters; this activity was specifically inhibited by a monoclonal anti-RecA antibody. However, RecA1730 protein did not form complete filaments on ssDNA, as shown by two observations: (i) most of the protein did not elute with ssDNA during gel filtration; and (ii) binding of RecA1730 to ssDNA did not protect it from being digested by DNaseI. RecA1730 hydrolysed ATP in high salt but was defective in ssDNA-dependent ATP hydrolysis. These results strongly suggest that RecA1730 binds to ATP and ssDNA but does not form normal nucleoprotein filaments.Abbreviations RecAwt RecA wind-type protein - ssDNA singlestranded DNA - dsDNA dmble-stranded DNA     

A new homeobox-leucine zipper gene from Arabidopsis thaliana

We have isolated a homeobox-containing gene from Arabidopsis thaliana using a degenerate oligonucleotide probe corresponding to the most conserved region of the homeodomain. This strategy has been used previously to isolate homeobox-containing genes from Caenorhabditis, and recently from A. thaliana. The Arabidopsis genes have an unusual structure in that they have a leucine zipper motif adjacent to the carboxy terminal region of the homeo domain, a feature not found in homeobox-containing genes isolated from animals. We report the isolation and primary structure of a new member of this Arabidopsis homeobox-leucine zipper gene family. This new member has the homeodomain and leucine-zipper motif similar to the two genes previously identified, but differs from these genes in the part corresponding to the carboxy terminus of the polypeptide, as well as in size and isoelectric point of the protein.     

Bacillus anthracis but not always anthrax

Gram-positive bacilli isolated during epidemiological investigations which, on the basis of conventional tests, resemble Bacillus anthracis but which fail to produce the capsule or to induce anthrax in test animals have long been dismissed in clinical and veterinary laboratories as B. cereus or simply as unidentified Bacillus spp. and thereupon discarded as inconsequential. In this study, the application of newly available DNA probe, polymerase chain reaction and specific toxin antigen detection technology has revealed that a proportion of such strains are B. anthracis which lack the plasmid carrying the capsule gene (pXO2). While these techniques cannot, of course, be used to confirm the identities of strains resembling B. anthracis but which also lack the plasmid carrying the toxin genes (pXO1), the likelihood that these also are bonajide B. anthracis becomes more acceptable. (As yet no naturally occurring pXOl^-/2⁺ strains have been found.) At this point, the significance of the presence of such avirulent forms of B. anthracis in specimens can only be a subject for speculation, but the possibility that they may be indicators of virulent parents somewhere in the system being examined must be considered.     

Disruption of imprinting by memory inhibitors

Several amnestic drugs were administered intracranially to day-old chicks at selected times around a 10-min exposure to an imprinting stimulus. The drugs used were monosodium glutamate, ouabain, cycloheximide and amino-iso-butyrate. The chicks were tested for 10 min in the same apparatus two days later, and the time spent following the stimulu was recorded., The index of memory retention was the difference between the time spent following on test and the time spent following on the initial exposure. When compared with saline-injected control, glutamate administered 5 min before the beginning of the initial exposure was effective in producing a reduction in following times and hence amnesia. Ouabian was effective when injeced before the beginning and immediately after the end of the initial exposure; while cycloheximide was effective when administered as late as 5 min after the initial exposure. The effective times of administration for the drugs to produce a reduction in following times were similar to that observed for amnesia in passive avoidance memory tasks. The increase in following shown by the control chicks was not a developmental effect due to the increae in age on test. Experiments involving a choice of stimuli on test support the invovement of a memoryrelated phenomenon in these experiments.