Oligochaeta in Spartina stems: the microdistribution of Enchytraeidae and Tubificidae in a salt marsh,Sapelo Island,USA

The distribution and abundance of Enchytraeidae and Tubificidae in and around Spartina alterniflora plants in a tidal salt marsh on Sapelo Island, Georgia, USA were studied using two different sampling techniques: wet funnel extraction and stem dissection. At least 80% of all worms inhabited leaf sheaths at the bases of S. alterniflora plants, and densities were low in sediment, root and surface debris samples. Oligochaete densities were dependent on the position within the marsh, the height on stems and the stage of sheath decay. Six predominant species were identified and included Marionina appendiculata, Marionina spartinae, Marionina waltersi, Marionina paludis, and Monopylephorus parvus. Individual species were distributed differently on stems and enchytraeids were more common than tubificids on standing-dead and further up S. alterniflora stems. Estimates of oligochaete densities in salt marsh habitats are increased dramatically when the numbers of worms on stems are considered. Possible advantages of the stem microhabitat are discussed in relation to the biology and ecology of oligochaetes.     

The differential expression of lamin epitopes during mouse spermatogenesis

The presence of lamin proteins in mouse spermatogenic cells has been examined by using an anti-lamin AC and an anti-lamin B antisera which recognize somatic lamins A and C, and somatic lamin B, respectively. Anti-lamin B binds to the nuclear periphery of all cell types examined, including Sertoli cells, primitive type A spermatogonia, preleptotene, leptotene, zygotene and pachytene spermatocytes, and round spermatids. In sperm nuclei, the antigenic determinants are localized to a narrow domain of the nucleus. However, after removing the perinuclear theca, anti-lamin B localizes to the entire nuclear periphery in a punctate pattern, suggesting that it is binding to determinants previously covered by the theca constituents. On immunoblots anti-lamin B reacts with a ～ 68 kD polypeptide in all germ cells and, to a lesser extent, with four additional polypeptides present only in meiotic and post-meiotic nuclear matrices. Anti-lamin AC also reacts with the perinuclear region of the somatic cells in the testes, in particular, those of the interstitium and also the Sertoli cells of the seminiferous epithelium. In contrast to anti-lamin B, anti-lamin AC does not bind to the germ cells at any stage of spermatogenesis. In addition, nuclear matrix proteins from isolated spermatogenic cells do not bind anti-lamin AC on immunoblots, suggesting the lack of reactivity is not due to the masking of any antigenic sites. These data demonstrate that germ cells contain lamin B throughout spermatogenesis, even during meiosis and spermiogenesis when the nuclear periphery lacks a distinct fibrous lamina. © 1993 Wiley-Liss, Inc.     

Reciprocal translocation and the Philadelphia chromosome

Summary We examined metaphases from three patients with chronic myeloid leukaemia and a typical Philadelphia chromosome with one chromosome 9 as the recipient to determine whether the 9q+ 22q- translocation is reciprocal. Good quality G-banded photographs of the chromosomes concerned were subjected to light absorption density analysis. This provided enlarged tracings corresponding to the relevant chromosome regions and so facilitated accurate measurement. This technique has unambiguously shown that the typical Philadelphia chromosome results from a reciprocal translocation and that probably no material is gained or lost in the exchange. Furthermore, in a total of six patients for whom sequential G and C banding was performed, the chromosome 9 with the largest block of centromeric heterochromatin received the translocated material. We offer tentative explanations for this curious observation.     

The isolation and identification of the female sex pheromones of the red bollworm moth, Diparopsis castanea

The female sex pheromones of the red bollworm moth, Diparopsis castanea, were isolated by solvent extraction of the terminal abdominal segments of the female moth followed by purification of the solvent extract by liquid-solid and gas chromatography. The pheromones were identified by gas chromatographic analysis, micro-ozonolysis, infra-red and mass spectroscopy, and comparison with synthetic material. The major pheromone was 9,11-dodecadien-1-yl acetate (80 : 20 trans : cis). Minor components identified were trans 9-dodecen-1-yl acetate, 11-dodecen-1-yl acetate, and dodecan-1-yl acetate.     

Hepatitis Delta Virus RNA Editing Is Highly Specific for the Amber/W Site and Is Suppressed by Hepatitis Delta Antigen

RNA editing at adenosine 1012 (amber/W site) in the antigenomic RNA of hepatitis delta virus (HDV) allows two essential forms of the viral protein, hepatitis delta antigen (HDAg), to be synthesized from a single open reading frame. Editing at the amber/W site is thought to be catalyzed by one of the cellular enzymes known as adenosine deaminases that act on RNA (ADARs). In vitro, the enzymes ADAR1 and ADAR2 deaminate adenosines within many different sequences of base-paired RNA. Since promiscuous deamination could compromise the viability of HDV, we wondered if additional deamination events occurred within the highly base paired HDV RNA. By sequencing cDNAs derived from HDV RNA from transfected Huh-7 cells, we determined that the RNA was not extensively modified at other adenosines. Approximately 0.16 to 0.32 adenosines were modified per antigenome during 6 to 13 days posttransfection. Interestingly, all observed non-amber/W adenosine modifications, which occurred mostly at positions that are highly conserved among naturally occurring HDV isolates, were found in RNAs that were also modified at the amber/W site. Such coordinate modification likely limits potential deleterious effects of promiscuous editing. Neither viral replication nor HDAg was required for the highly specific editing observed in cells. However, HDAg was found to suppress editing at the amber/W site when expressed at levels similar to those found during HDV replication. These data suggest HDAg may regulate amber/W site editing during virus replication.