Requirement of monovalent cations in the acrosome reaction of guinea pig spermatozoa

The majority of the spermatozoa precapacitated in Ca²⁺-free medium underwent the acrosome raction rapidly when they were transferred to Ca²⁺-containing medium. The presence of Na⁺ and Ca²⁺ in the medium was essential for the acrosome reaction. The vast majority of spermatozoa failed to undergo the reaction in Ca²⁺ medium lacking monovalent ions, although they remained motile. At the concentration of 140 mM, Na⁺, K⁺, Rb⁺, and Cs⁺ all supported the reaction at the maximum level, but at 50 mM the latter three ions were not as effective as Na⁺. Li⁺ was least effective in supporting the reaction. Virtually no acrosome reactions took place when precapacitated spermatozoa were first exposed to Na⁺ medium (no Ca²⁺) and then to Ca²⁺ medium (no Na⁺). On the other hand, a considerably higher proportion of spermatozoa acrosome reacted when they were exposed to these media in the reverse order. The most efficient acrosome reactions took place when the medium contained both a monovalent ion (Na⁺) and Ca²⁺ simultaneously. Possible mechanisms by which monovalent and divalent cations participate in the acrosome reaction are discussed.     

Role of B-ring of colchicine in its binding to Zn(II)-induced tubulin-sheets

Colchicine-tubulin dimer comPlex, a Potent inhibitor of normal microtubule assembly undergoes extensive self-assembly in the Presence of 1 X 10^-4 M zinc sulPhate. Polymers assembled from colchicine-tubulin dimer comPlexes are sensitive to cold. Although colchicine can be accomodated within the Polymeric structure, the drug cannot bind to tubulin subunits in the intact Polymers. This is evidenced by the fact that (a) the colchicine binding activity of tubulin is lost when allowed to Polymerize with zinc sulPhate, (b) the loss in colchicine binding could be Prevented by Preincubation of tubulin with 1 X 10^-3 M CaCl₂ or 1 X 10^-5 M vinblastine sulPhate and finally (c) no loss in colchicine binding activity is found when tubulin is kePt at a concentration far below the critical concentration for Polymerization. Unlike colchicine, its B-ring analogues desacetamido colchicine (devoid of the B-ring subtituent) and 2-methoxy-5-(2′, 3′, 4′-trimethoxyPhenyl) troPone (devoid of the B-ring) can bind to tubulin subunits in the intact Polymers. Thus we conclude that the colchicine binding domain on the tubulin molecule is mostly (if not comPletely) exPosed in the Zn(II) -induced Polymers and the B-ring substituent Plays a major role in determining the binding ability of a colchicine analogue to tubulin in the intact Zn(II) -induced sheets.     

S100 is present in developing chicken neurons and Schwann cells and promotes motor neuron survival in vivo.

We used polyclonal antisera recognizing S100, a small acidic protein highly enriched in nervous tissue, to stain sections of embryonic chicken lumbosacral spinal cord and hindlimb. S100 immunoreactivity was detected in developing sensory neurons of the dorsal root ganglia (DRG) and motor neurons of the ventral spinal cord as early as embryonic day (E) 5, and staining persisted through hatching. In contrast, expression of S100 first became apparent in Schwann cells at E13, just before myelination, and was not detected in developing skin or muscle. Since S100 beta was present in motor and sensory neurons and is known to promote neuronal survival and neurite extension in vitro (Winningham-Major, Staecker, Barger, Coats, and Van Eldik, 1989), we tested the ability of S100 to promote neuron survival in an in ovo survival assay. Addition of S100 to chick embryos in ovo during the period of naturally occurring motor neuron cell death resulted in a significant increase in motor neuron survival, but had no effect on the in vivo survival of sensory neurons in the DRG. The findings that S100 is present in spinal motor neurons and that the addition of S100 enhances the survival of these cells in vivo are consistent with the possibility that S100 may act as a naturally occurring neuron survival factor during development.     

Terminal oxydation pattern of a soil Pseudomonad (PL-strain)

Summary The organism grown on ¹-p-menthene was found to grow without any lag on methyl isopropyl ketone, isobutyrate, succinate, malate, lactate and acetate. Isobutyrate or acetate grown cells grew on ¹-p-menthene after a lag and showed comparatively little growth on -isopropyl pimelic acid.¹-p-menthene grown cells oxidized readily isobutyrate, acetate, succinate, malate, -ketoglutarate and methacrylate. Methylmalonate, methyl isopropyl ketone and -isopropyl pimelic acid were rather oxidized at slow rates. Isobutyrate grown cells, on the other hand, showed from very good to very fair oxidation rates with succinate, isobutyrate, acetate, malate, methacrylate, -ketoglutarate. Methylmalonate was oxidized much better and methyl isopropyl ketone was oxidized slowly.¹-p-menthene and isobutyrate grown cells were used under resting conditions with different substrates in the presence of arsenite. Analysis of the reaction products indicated the accumulation of a keto acid. Qualitative analysis of the keto acid formed by TLC showed pyruvate as the major ketocarboxylic acid with one or two other minor components. The major component had been isolated and identified as pyruvic acid. Similar results had been obtained by working with crude cell-free enzyme preparations.Based on these results two possible mechanisms of degradation of isobutyrate have been suggested. A plausible pathway has been outlined for the terminal oxidation pattern in the Pseudomonad (PL-strain).Abbreviations NAD Nicotinamide adenine dinucleotide - FAD Flavine adenine dinucleotide - -KGA -keto-glutaric acid - CFE cell-free extract - CoA coenzyme A in its reduced state Communication number 1426 from the National Chemical Laboratory.     

Induction of a high affinity binding site for auxin in Avena root membrane

A membrane preparation from Avena sativa root has been found to contain only one low-affinity IAA-binding site having a K_d value of 8.4 ×     

Survey of the essential oil in Spartina cynosuroides

The essential oil of the giant cordgrass, Spartina cynosuroides, was isolated in 0.02”/ yield by steam distillation. Analysis by GLC-MS showed the     

Distribution and structure of the adrenocortical homologue in the garpike

The microanatomy of the yellow corpuscles (adrenocortical homologue, AH) in the holostean fish, Lepisosteus spp. was studied by serial sectioning, steroid histochemistry, and electron microscopy. The modification of this tissue to short-term ACTH treatment was also observed. The distribution of the AH within the renal tissue of the garpike phylogenetically represents a more advanced condition than that seen in its closest holostean relative, the bowfin, and appears to approximate that in teleosts. The homology of this tissue of vertebrate adrenocortical tissue was established by the positive identification of the enzyme, gamma 5-3 beta-hydroxysteroid dehydrogenase, and by the ultrastructural features of the cells before and after ACTH administration. The AH cells possess fine structural features characteristic of steroidogenic cells, namely, polymorphic mitochondria with tubular cristae, abundant tubules of smooth endoplasmic reticulum, a prominent Golgi complex, and lipid droplets. Other interesting features include the presence of annulate lamellae and a variety of dense bodies. Digitonin perfusion results in the deposition of presumed, cholesterol-digitonide crystalline spicules on the surface microplicae of the cells and as dense accumulations in association with smooth endoplasmic reticulum. ACTH administration results in swelling of mitochondria, a loss of their cristae, and a smooth decrease in electron density of their matrices. Alterations also occur in the smooth and rough endoplasmic reticulum, and large osmiophilic inclusions of irregular profile appear. Some of the ACTH-induced modifications are similar to those observed in the adrenocortical cells of other vertebrate groups following comparable stimulation.     

Cloning of ribosomal RNA genes from an Indian isolate ofGiardia lamblia and the use of intergenic nontranscribing spacer regions in the differentiation ofGiardia from other enteric pathogens

The ribosomal RNA genes from an Indian isolate ofGiardia lamblia have been cloned and characterized with respect to size, composition and copy number. Southern blotting and rDNA cloning ofGiardia lamblia revealed that genes coding for ribosomal RNA (rRNA) are exceptionally small and are encoded within a 5.6 kb genome fragment repeat. The rDNA repeat unit of this isolate was found to be highly G-C rich like other human isolates and the physical map showed severalSmaI sites. There are 132 copies of the rDNA repeat unit per cell in a head to tail arrangement. Two fragments corresponding to intergenic (0.2 kb and 0.3 kb) region and one (0.8 kb) containing both an intergenic region and a small part of the small subunit ribosomal RNA (SS rRNA) have been identified within the rDNA. These were used in heterogeneity studies ofGiardia isolated from two geographic locations as well as in the analysis of cross reactivity with other enteric organisms. In Southern blots, all the three fragments were found to be highly specific for the differential diagnosis ofGiardia spp. from the other enteric pathogens. These findings should help in developing a sensitive and more specific method for the diagnosis of giardiasis over currently available techniques.     

Spray reagent for the detection of amino acids on thin layer chromatography plates

Summary A spray reagent for easy identification of amino acids on thin-layer chromatography plates has been introduced. The reagent is capable of developing various distinguishable colours with many of them. A probable mechanism for such colour formation has also been proposed.     

Optimization of tannase biosynthesis by a newly isolated Rhizopus oryzae

A strain isolated locally and identified as Rhizopus oryzae (RO, IIT KGP) was found to synthesise an extracellular enzyme, tanin acyl hydrolase, showing its degradability of tannic acid to gallic acid. For maximizing the enzyme secretion in the fermented broth, the influencing parameters were optimized in shake flask culture. Experiments showed that modified Czapek dox medium with 2% tannic acid, 1% glucose, 0.05% sodium nitrate incubated for 4 days with 2 days old inoculum was the optimum for the synthesis of tannase by Rhizopus oryzae (RO, IIT KGP). Maximum enzyme activity was found to be 6.12 U/ml.