Morphological and cytological investigations ofUlothrix zonata and taxonomy of the related species

The present communication deals with the observations made on the morphology, reproduction and cytology ofUlothrix zonata (Weber & Mohr)Kütz. in culture. The alga displays a remarkable phenotypic plasticity in nature as well as in culture. The present study provides additional evidence of karyology in support ofLokhorst andVroman's treatment ofU. zonata which merges a number of earlier described species in it. The cytological details and chromosome number (n = 10) determined for the Indian isolates ofU. zonata agree with those ofSarma for the British material.NBRI Research Publication No. 63 (N.S.)     

In vivo phosphorylation of two myelin basic proteins of developing rabbit brain

Examination of 15-day-old rabbit brain myelin proteins by sodium dodecyl sulfate-slab gel electrophoresis revealed the presence of a basic protein with a molecular weight of 21,000 (21K protein) which was not previously reported in this species. This protein exhibited characteristic bluish green color with amido black and gave an amino acid composition strikingly similar to large basic protein (LBP). It formed a line of identity with LBP when diffused against antiserum to chicken brain basic protein. The concentration of LBP (18.9 micrograms/mg of dry myelin) is 6-fold greater than that of the 21K protein(3.31 micrograms/mg of dry myelin) in rabbit brain myelin. After the intracerebral injection of [32P]orthophosphoric acid, both LBP and 21K protein were found to be phosphorylated. [32P]Phosphate in the purified preparations of these proteins was covalently linked by phosphoester bonds to serine and threonine residues. The specific radioactivity of the 21K protein (84,693 cpm/mg of protein) was not significantly higher than LBP (69,797 cpm/mg of protein).     

Accumulation and turnover of the classical Folch-Lees proteolipid proteins in developing and adult rat brain.

The turnover of classical Folch-Lees proteolipid proteins was studied after administration of [2,3-3H]tryptophan to both developing and adult rat brain. The animals were killed from 2h to 250 days after subcutaneous injections of [3H]tryptophan. The measured specific radioactivity in developing brain attained maximum value 24h after the administration of label, whereas the total radioactivity per brain reached a maximum 21 days after injection. The half-life of proteolipid protein from the measured specific radioactivity was 7-20 days, depending on the time-points used for the calculation, whereas calculation from total radioactivity between 28-77 and 91-257 days gave half-lives of 35-40 and 188 days respectively. In contrast, in animals injected at 40 days of age, the half-life from the whole-brain-radioactivity data was 188 days. The problem of the recycling of radioactivity for the synthesis of myelin proteins from either a general or a discrete amino acid pool is discussed.     

Studies on north indian volvocales-III. Fertilization in Eudorina californica (shaw) goldstein

The present communication deals with the details of sexual reproduction including the process of fusion of gametes in Eudorina californica (Shaw) Goldstein (earlier described as E. indica lyengar). The present observations are compared with those on other species in which the process of fusion was recorded.     

Biochemical maturation of human central nervous system myelin.

—A developmental study of the lipid and protein composition of human CNS myelin was undertaken. The relative concentrations of the major lipid classes, cholesterol, glycolipids and phospholipids exhibited little change except for a modest decrease in the concentration of the phospholipids. In contrast to the total phospholipids, marked variations in the relative concentrations of individual phospholipids were found. Sphingomyelin increased over two-fold, and phosphatidyl choline decreased to almost half its original concentration. While the concentration of total myelin protein remained constant during maturation, variations in the concentrations of individual proteins were observed. Basic protein constituted 8·5 per cent of the total myelin proteins in the newborn brain and increased to about 30 per cent of the protein in the older ages. The concentrations of proteolipid protein and DM-20 seemed to increase with age, while the relative amounts of high molecular weight proteins decreased. The presence of myelin basic protein in newborn human brain was confirmed by electrophoretic studies involving several different polyacrylamide gel systems and by immunodiffusion experiments which showed a reaction of identity between a constituent present in the fraction containing the presumptive myelin basic protein and authentic myelin basic protein isolated from adult human brain.     

Woloszynskia stoschii andGymnodinium indicum,two new freshwater dinoflagellates from India: Morphology,reproduction and cytology

The distinctive morphological and karyological features of the two new species, collected from freshwater habitats in North India, are presented and compared with those of related taxa of the generaWoloszynskia andGymnodinium. Asexual reproduction takes place through zoospore formation and sexual reproduction through planozygotes inWoloszynskia stoschii.     

Zinc finger nucleases: custom-designed molecular scissors for genome engineering of plant and mammalian cells

Custom-designed zinc finger nucleases (ZFNs), proteins designed to cut at specific DNA sequences, are becoming powerful tools in gene targeting—the process of replacing a gene within a genome by homologous recombination (HR). ZFNs that combine the non-specific cleavage domain (N) of FokI endonuclease with zinc finger proteins (ZFPs) offer a general way to deliver a site-specific double-strand break (DSB) to the genome. The development of ZFN-mediated gene targeting provides molecular biologists with the ability to site-specifically and permanently modify plant and mammalian genomes including the human genome via homology-directed repair of a targeted genomic DSB. The creation of designer ZFNs that cleave DNA at a pre-determined site depends on the reliable creation of ZFPs that can specifically recognize the chosen target site within a genome. The (Cys₂His₂) ZFPs offer the best framework for developing custom ZFN molecules with new sequence-specificities. Here, we explore the different approaches for generating the desired custom ZFNs with high sequence-specificity and affinity. We also discuss the potential of ZFN-mediated gene targeting for ‘directed mutagenesis’ and targeted ‘gene editing’ of the plant and mammalian genome as well as the potential of ZFN-based strategies as a form of gene therapy for human therapeutics in the future.     

Movement of the decoding region of the 16 S ribosomal RNA accompanies tRNA translocation

The ribosome undergoes pronounced periodic conformational changes during protein synthesis. Of particular importance are those occurring around the decoding site, the region of the 16 S rRNA interacting with the mRNA-(tRNA)(2) complex. We have incorporated structural information from X-ray crystallography and nuclear magnetic resonance into cryo-electron microscopic maps of ribosomal complexes designed to capture structural changes at the translocation step of the polypeptide elongation cycle. The A-site region of the decoding site actively participates in the translocation of the tRNA from the A to the P-site upon GTP hydrolysis by elongation factor G, shifting approximately 8 A toward the P-site. This implies that elongation factor G actively pushes both the decoding site and the mRNA/tRNA complex during translocation.     

Doppler ultrasound scoring to predict chemotherapeutic response in advanced breast cancer

Background

Von Hippel-Lindau (VHL) disease is an autosomal dominant inherited disease. It is relatively recent that type 2C was identified as a separate group solely presenting with pheochromocytomas. As an illustration, an interesting case is presented of a pregnant woman with refractory hypertension. It proved to be the first manifestation of bilateral pheochromocytomas. The family history may indicate the diagnosis, but only identification of a germ line mutation in the DNA of a patient will confirm carriership.

Case presentation

A 27 year pregnant patient with intra uterine growth retardation presented with hypertension and pre-eclampsia. Magnetic resonance imaging revealed bilateral adrenal pheochromocytoma. She underwent laparoscopic adrenelectomy and a missense mutation (Gly93Ser) in exon 1 of the VHL gene on chromosome 3 (p25 - p26) was shown in the patient, her father and her daughter confirming the diagnosis of VHL.

Conclusion

In almost all VHL families molecular genetic analysis of DNA will demonstrate an inherited mutation. Because of the involvement in several organs, periodic clinical evaluation should take place in a well coordinated, multidisciplinary setting. VHL disease can be classified into several subtypes. VHL type 2C patients present with pheochromocytomas without evidence of haemangioblastomas in the central nervous system and/or retina and a low risk of renal cell carcinoma. Therefore, in such families, periodic clinical screening can be focussed on pheochromocytomas.