Hermaphroditism in icerya zeteki cockerell,and the mechanism of gonial reduction in iceryine coccids (coccoidea: Margarodidae morrison)

In the Panamanian iceryine coccid Icerya zeteki Cockerell (Family Margarodidae Morrison) all females become hermaphroditic early in the first instar; occasional males arise from unfertilized eggs, but self-fertilization is assured by the protandry of the hermaphrodite. In the development of the ovotestis, initiation of the male phase is brought about by haploidization of those germ cells destined for spermatogenesis. In both Icerya zeteki and Icerya purchasi this gonial reduction results from the degeneration and elimination of one genome during prophase. Except for minor variations in the coiling cycle of spermatocytes, the chromosomes (n=2) of I. zeteki correspond closely to those of all other haplo-diploid iceryines known. The present status of the species Icerya zeteki Cockerell is reviewed, and on both taxonomicand cytological grounds is judged to be uncertain.Supported in part by National Science Foundation Grant GB — 1922.     

The elimination and differentiation of chromosomes in the germ line of sciara

The germ line chromosomes of S. coprophila have been followed from the time of origin of the germ cells up to the time of meiosis in the male and up to first larval molt in the female. The mechanism which prevents the accumulation of L (limited) chromosomes in the germ line is a unique process of chromosome elimination: it occurs in male and female embryos after the germ cells have migrated from the pole plasm to the definitive gonad site, and it involves the movement of whole L chromosomes through the nuclear membrane into the cytoplasm. The extra paternal X chromosome is eliminated from the germ cells at the same time and in the same manner. Following this elimination there is a cytological differentiation of the chromosomes remaining inside the nucleus. First, the 4 paternal homologues of the regular complement undergo a loosening of coils and become light-staining whereas the maternal homologues remain condensed like the L's. Next, the L chromosomes undergo a process of extreme attenuation and dispersion following which they return to the condensed state. H³-thymidine autoradiography on gonial and premeiotic cells in the testis reveals that the L chromosomes undergo DNA replication at the end of the S period, also that there are asynchronies in DNA synthesis among the regular chromosomes. The phenomena of differential chromosome staining and asynchronous DNA replication are considered in the light of current theory regarding heterochromatization and gene inactivation, also in relation to the phenomenon of chromosome imprinting encountered in this genus.The studies reported here were supported by the National Science Foundation grants GB-42 and GB-2857, and in part by Contract No. AT-(40-1)-2690 under the Division of Biology and Medicine, U.S. Atomic Energy Commission.Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, in the Faculty of Pure Science, Department of Botany, Columbia University. This work was carried out in the laboratory of Professor J. Herbert Taylor and has been supported in part by U.S. Public Health Training Grant No. 2 T 1-GM-216-05. Grateful acknowledgement is made to Professor Spencer W. Brown, Department of Genetics, University of California, Berkeley, in whose laboratory the final studies were completed.     

A rapid method for the detection of potentially viable Mycobacterium leprae in human biopsies: a novel application of PCR

Abstract A simple procedure based on the polymerase chain reaction has been developed to detect Mycobacterium leprae , rapidly and unambiguously, in biological samples. Its application to small numbers of M. leprae cells (∼ 10²) isolated from armadillo liver, mouse footpads or human biopsies is discussed.     

Variability of entrainment of cohesive sediments in freshwater

Estimates of sediment entrainment are required for models of particle transport in lakes and estuaries but are difficult to make because of the multiplicity of factors affecting cohesiveness of surficial sediments. We present results of sediment resuspension studies performed in an annular flume calibrated with laser-Doppler velocimetry. In our experiments, using sediments collected from two sites in the R. Raisin which flows into L. Erie and from one site in the western basin of L. Erie near the mouth of the R. Raisin, we applied shear stresses at the sediment-water interface in steps from 2 to 12 dyne/cm². Percent water content at the surface of the sediments was either 77 or 74%, and trials were run with and without oxygenating the water overlying the sediments. Entrainment rates as a function of shear stress at the sediment-water interface were best described by a power-law relationship. All but 14% of the variability in the power law expression was due to shear stress and percent water content; the variability not accounted for was due to differences in particle size distributions, chemical properties, and biological activity in the sediments.     

Analysis of HLA and Disease Susceptibility: Chromosome 6 Genes and Sex Influence Long-QT Phenotype

The long-QT (LQT) syndrome is a genetically complex disorder that is characterized by syncope and fatal ventricular arrhythmias. LQT syndrome, as defined by a prolonged electrocardiographic QT interval, has a higher incidence in females than in males and does not exhibit Mendelian transmission patterns in all families. Among those families that are nearly consistent with Mendelian transmission, linkage between a locus for LQT syndrome and the H-ras-1 locus on the short arm of chromosome 11 has been reported in some families but not in others. Earlier analyses suggesting that LQT syndrome might be caused by a gene in the HLA region of chromosome 6 were not confirmed by standard linkage analyses. Here, we present an analysis of HLA haplotype sharing among affected pedigree members, showing an excess of haplotype sharing in a previously published Japanese pedigree and possibly also in 15 families of European descent. The haplotypes shared by affected individuals derive from both affected and unaffected parents. In an analysis of independent (unrelated) HLA haplotypes, we also found a nonrandom distribution of HLA-DR genes in LQT syndrome patients compared with controls, suggesting an association between the LQT phenotype and specific HLA-DR genes. Our data indicate that DR2 has a protective effect and, particularly in males, that DR7 may increase susceptibility to the LQT syndrome. Thus, LQT syndrome may be influenced by genes on chromosomes 11 and 6, possibly with a sex-specific effect. These results provide a model for an effect of HLA-region genes inherited from either parent on the expression of an illness that may be determined principally by alleles at loci not linked to HLA.     

Chiral HPLC with carbohydrate carbamates: Influence of support structure on enantioselectivity

The effect of particle size and pore size of the aminopropylated silica support for cellulose tris(phenylcarbamate) and tris(3,5-dimethylphenylcarbamate) chiral HPLC phases was investigated. It was necessary to reduce phase loading below 20% w/w as pore size and particle size were reduced, but high efficiency columns could be prepared at a 15% w/w loading on 5 and 2.5 μm supports with 120-Å-diameter pores. The 2.5 μm phase permits the use of relatively high flow rates and very efficient enantioselective separations of a range of chiral compounds could be achieved in less than 3 min. © 1994 Wiley-Liss, Inc.     

Genetic disruption of mammalian endoplasmic reticulum-associated protein degradation: Human phenotypes and animal and cellular disease models

Endoplasmic reticulum-associated protein degradation (ERAD) is a stringent quality control mechanism through which misfolded, unassembled and some native proteins are targeted for degradation to maintain appropriate cellular and organelle homeostasis. Several in vitro and in vivo ERAD-related studies have provided mechanistic insights into ERAD pathway activation and its consequent events; however, a majority of these have investigated the effect of ERAD substrates and their consequent diseases affecting the degradation process. In this review, we present all reported human single-gene disorders caused by genetic variation in genes that encode ERAD components rather than their substrates. Additionally, after extensive literature survey, we present various genetically manipulated higher cellular and mammalian animal models that lack specific components involved in various stages of the ERAD pathway.     

Isolation and culture of rat superior mesenteric artery smooth muscle cells

Summary The structure and function of vascular smooth muscle cells have been extensively investigated with the aid of in vitro culture techniques. The majority of studies have utilized aortic tissue as the source of cells. We present here a method for isolating and culturing smooth muscle cells of the rat superior mesenteric artery, an elasto-muscular vessel that is structurally and functionally different from the aorta. Cells were isolated from partially digested explants and characterized by immunochemical and biochemical techniques. Unlike cultured fibroblasts, the cultured cells stained positive for smooth muscle specific actin. The cells also produced laminin and type IV collagen in culture. This method provides a means for the isolation of large numbers of viable smooth muscle cells from the superior mesenteric artery which can be propagated in culture for in vitro study.     

On the cytotaxonomy of phasmids (Phasmatodea)

Summary A wide diversity in chromosome complement is found in two species of phasmids of the primitive group Prisopini—Prisopus ariadne Hebard and Prisopus berosus Westwood. P. ariadne has a diploid male complement of 28, comprising 13 pairs of relatively large mediokinetic autosomes and Neo XY sex chromosomes. P. berosus, 2n =49, has relatively small autosomes most of which are mediokinetic, and retains the XO—XX sex mechanism. Chromosomal polymorphism in this species is suggested by the presence of an unequal pair of autosomes and a structural differentiation in the X in one of two males studied.The relative amount of DNA per nucleus in male germ cells (Peulgen cytophotometry) shows a significant difference in total chromosomal content between the complements of the two species.These data are discussed with reference to the cytotaxonomy of phasmids.Supported in part by research grant G-4370 from the National Institutes of Health, Public Health Service.     

Feminine Matters: Women's Religious Practices in a Portuguese Town.

Feminine Matters: Women's Religious Practices in. Portuguese Town. Lena Gemzöe. Berlin: Walter de Gruyter, 2000. 273 pp.