Low molecular weight factor in bovine caudal epididymal fluid that stimulates calcium uptake in caput spermatozoa

Secretions from the mammalian epididymis contain proteins that bind to developing sperm and are presumed to play a role in sperm maturation. The biochemical functions in sperm of most of these proteins are not known. In this report we describe the presence of a low molecular weight compound in bovine caudal epididymal luminal fluid (CF) that has a potent stimulatory effect on calcium (⁴⁵Ca²⁺) uptake in immature caput epididymal spermatozoa. The studies were initially undertaken to characterize the effect of the protein caltrin, present in bovine seminal plasma (BSP), on calcium uptake into caput spermatozoa. Caltrin is known to block calcium influx into mature bovine sperm. Unexpectedly, the kinetics of calcium uptake into caput sperm showed a biphasic response when treated with BSP, namely, a stimulation of uptake at 1 to 5 min and inhibition of uptake after this time. Since caudal sperm do not show this biphasic response, we reasoned that BSP contained a factor derived from CF that must interact with developing sperm before the binding of caltrin to sperm can prevent further calcium uptake. We first demonstrated that preincubation of caput sperm with CF eliminated the biphasic calcium uptake effect induced in caput sperm by BSP and that caudal fluid alone had a potent stimulatory effect on calcium uptake in caput sperm. Half-maximal stimulation (fivefold over control) occurred at a caudal fluid protein concentration of 0.27 mg/ml. Partial purification of the factor indicates that it is of low molecular weight (MW ～ 1,000), but further chemical characterization has not been carried out and its epididymal site of origin is not known. The results indicate that the regulation of intracellular calcium levels in sperm differs in immature and mature bovine sperm in that an epididymal factor promotes calcium uptake during epididymal maturation, and the seminal fluid protein caltrin prevents it at ejaculation.     

Bound auxin metabolism in cultured crown-gall tissues of tobacco

Bound auxin metabolism in cultured crown-gall tumor cells and pith callus of tobacco was examined by feeding radiolabeled auxins and auxin conjugates. In all tissues fed [¹⁴C]indoleacetic acid (IAA), at least one-third of the IAA was decarboxylated, and most of the remaining radiolabel occurred in a compound(s) which did not release IAA with alkaline hydrolysis. In cells transformed by the A6 strain of Agrobacterium tumefaciens, the only detectable IAA conjugate was indole-3-acetylaspartic acid (IAAsp), whereas cells transformed by the gene 2 mutant strain A66 produced an unidentified amide conjugate but no IAAsp. By contrast, cells fed [¹⁴C]naphthaleneacetic acid (NAA) accumulated several amide and ester conjugates. The major NAA metabolite in A6-transformed cells was naphthaleneacetylaspartic acid (NAAsp), whereas the major metabolites in A66-transformed cells were NAA esters. In addition, A66-transformed cells produced an amide conjugate of NAA which was not found in A6-transformed cells and which showed chromatographic properties similar to the unknown IAA conjugate. Pith callus fed [¹⁴C] NAA differed from both tumor lines in that it preferentially accumulated amide conjugates other than NAAsp. Differences in the accumulation of IAA and NAA conjugates were attributed in part to the high capacity of tobacco cells to oxidize IAA and in part to the specificity of bound auxin hydrolases. All tissues readily metabolized IAAsp and indole-3-acetyl-myo-inositol, but hydrolyzed NAAsp very slowly. Indirect evidence is provided which suggests that ester conjugates of NAA are poorly hydrolyzed as well. Analysis of tissues fed [¹⁴C]NAA together with high concentrations of unlabeled IAA or NAA indicates that tissue-specific differences in NAA metabolism were not the result of variation in endogenous auxin levels. Our results support the view that bound auxin hydrolysis is highly specific and an important factor controlling bound auxin accumulation.     

Design of peptides with branched beta-carbon dehydro-residues: syntheses, crystal structures and molecular conformations of two peptides, (I) N-Carbobenzoxy-DeltaVal-Ala-Leu-OCH3 and (II) N-Carbobenzoxy-DeltaIle-Ala-Leu-OCH3.

Highly specific structures can be designed by inserting dehydro-residues into peptide sequences. The conformational preferences of branched beta-carbon residues are known to be different from other residues. As an implication it was expected that the branched beta-carbon dehydro-residues would also induce different conformations when substituted in peptides. So far, the design of peptides with branched beta-carbon dehydro-residues at (i + 1) position has not been reported. It may be recalled that the nonbranched beta-carbon residues induced beta-turn II conformation when placed at (i + 2) position while branched beta-carbon residues induced beta-turn III conformation. However, the conformation of a peptide with a nonbranched beta-carbon residue when placed at (i + 1) position was not found to be unique as it depended on the stereochemical nature of its neighbouring residues. Therefore, in order to induce predictably unique structures with dehydro-residues at (i + 1) position, we have introduced branched beta-carbon dehydro-residues instead of nonbranched beta-carbon residues and synthesized two peptides: (I) N-Carbobenzoxy-DeltaVal-Ala-Leu-OCH3 and (II) N-Carbobenzoxy-DeltaIle-Ala-Leu-OCH3 with DeltaVal and DeltaIle, respectively. The crystal structures of peptides (I) and (II) have been determined and refined to R-factors of 0.065 and 0.063, respectively. The structures of both peptides were essentially similar. Both peptides adopted type II beta-turn conformations with torsion angles; (I): phi1 = -38.7 (4) degrees, psi1 = 126.0 (3) degrees; phi2 = 91.6 (3) degrees, psi2 = -9.5 (4) degrees and (II): phi1 = -37.0 (6) degrees, psi1 = 123.6 (4) degrees, phi2 = 93.4 (4), psi2 = -11.0(4) degrees respectively. Both peptide structures were stabilized by intramolecular 4-->1 hydrogen bonds. The molecular packing in both crystal structures were stabilized in each by two identical hydrogen bonds N1...O1' (-x, y + 1/2, -z) and N2...O2' (-x + 1, y + 1/2, -z) and van der Waals interactions.     

Induced Stress on Red Blood Cell Promotes Red Blood Cell-Endothelial Adhesion

Cell and Tissue Biology - Besides disease condition, very few stress stimulants were determined to provoke red blood cell (RBC) adhesion to endothelial cells (EC). However, the possible role of...     

An Extracellullar Nuclease from Bacillus Firmus VKPACU-1: Specificity and Mode of Action

An extracellular nuclease from Bacillus firmus VKPACU-1 was multifunctional enzyme, this nuclease hydrolyzed poly U rapidly and more preferentially than the other homopolyribonucleotides. Hydrolysis of RNA this enzyme released mononucleotides in the order 5′UMP > 5′AMP > 5′GMP where as in hydrolysis of DNA the mononucleotides in the order of 5′dAMP > 5′dGMP > 5′dTMP and oligonucleotides. Uridylic linkages in RNA and adenylic linkages in DNA were preferentially cleaved by the nuclease. Nuclease produced oligonucleotides having only 3’ hydroxyl and 5’ phosphate termini. Present nuclease hydrolyzed RNA and DNA released oligonucleotides as major end products and mononucleotides, suggesting an endo mode of action.     

Trends in inulinase production – a review

This article highlights the research work carried out in the production of inulinases from various inulin substrates using strains of bacteria, yeast and fungi. Inulin is one of the numerous polysaccharides of plant origin that contains glucose or fructose. It is used as a substrate in industrial fermentation processes and in food industries due to its relatively cheap and abundant source for the microbiological production of high-fructose syrups, ethanol and acetone–butanol. The various oligosaccharides derived from inulin also find their application in the medical and dietary sector. The inulinase acts on the β-(2,1)-D-fructoside links in inulin releasing D-fructose. Hence, this article illustrates the capability of various microbes in hydrolyzing the carbon at its optimum nutrient concentration and operating condition towards inulinase production.     

The contribution of endophytic bacteria to Albizia lebbeck-mediated phytoremediation of tannery effluent contaminated soil

Toxicity of chromium often impairs the remediation capacity of plants used in phytoremediation of polluted soils. In this study, we have identified Albizia lebbeck as a prospective chromium hyperaccumulator and examined cultivable diversity of endophytes present in chromium-treated and control saplings. High numbers (22–100%) of endophytic bacteria, isolated from root, stem, and leaf tissues, could tolerate elevated (1–3 mM) concentrations of K₂CrO₇. 16S rRNA gene sequence-based phylogenetic analysis showed that the 118 isolates obtained comprised of 17 operational taxonomic units affiliated with the proteobacterial genera Rhizobium (18%), Marinomonas (1%), Pseudomonas (16%), and Xanthomonas (7%) but also with members of Firmicutes genera, such as Bacillus (35%) and Salinococcus (3%). The novel isolates belonging to Salinococcus and Bacillus could tolerate high K₂CrO₇ concentrations (3 mM) and also showed elevated activity of chromate reductase. In addition, majority (%) of the endophytic isolates also showed production of indole-3-acetic acid. Taken together, our results indicate that the innate endophytic bacterial community assists plants in reducing heavy metal toxicity.