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.     

Spatiotemporal spread of Plasmodium falciparum mutations for resistance to sulfadoxine-pyrimethamine across Africa, 1990–2020

BackgroundSulfadoxine-pyrimethamine (SP) is recommended in Africa in several antimalarial preventive regimens including Intermittent Preventive Treatment in pregnant women (IPTp), Intermittent Preventive Treatment in infants (IPTi) and Seasonal Malaria Chemoprevention (SMC). The effectiveness of SP-based preventive treatments are threatened in areas where Plasmodium falciparum resistance to SP is high. The prevalence of mutations in the dihydropteroate synthase gene (pfdhps) can be used to monitor SP effectiveness. IPTi-SP is recommended only in areas where the prevalence of the pfdhps540E mutation is below 50%. It has also been suggested that IPTp-SP does not have a protective effect in areas where the pfdhps581G mutation, exceeds 10%. However, pfdhps mutation prevalence data in Africa are extremely heterogenous and scattered, with data completely missing from many areas.Methods and findingsThe WWARN SP Molecular Surveyor database was designed to summarize dihydrofolate reductase (pfdhfr) and pfdhps gene mutation prevalence data. In this paper, pfdhps mutation prevalence data was used to generate continuous spatiotemporal surface maps of the estimated prevalence of the SP resistance markers pfdhps437G, pfdhps540E, and pfdhps581G in Africa from 1990 to 2020 using a geostatistical model, with a Bayesian inference framework to estimate uncertainty. The maps of estimated prevalence show an expansion of the pfdhps437G mutations across the entire continent over the last three decades. The pfdhps540E mutation emerged from limited foci in East Africa to currently exceeding 50% estimated prevalence in most of East and South East Africa. pfdhps540E distribution is expanding at low or moderate prevalence in central Africa and a predicted focus in West Africa. Although the pfdhps581G mutation spread from one focus in East Africa in 2000, to exceeding 10% estimated prevalence in several foci in 2010, the predicted distribution of the marker did not expand in 2020, however our analysis indicated high uncertainty in areas where pfdhps581G is present. Uncertainty was higher in spatial regions where the prevalence of a marker is intermediate or where prevalence is changing over time.ConclusionsThe WWARN SP Molecular Surveyor database and a set of continuous spatiotemporal surface maps were built to provide users with standardized, current information on resistance marker distribution and prevalence estimates. According to the maps, the high prevalence of pfdhps540E mutation was to date restricted to East and South East Africa, which is reassuring for continued use of IPTi and SMC in West Africa, but continuous monitoring is needed as the pfdhps540E distribution is expanding. Several foci where pfdhps581G prevalence exceeded 10% were identified. More data on the pfdhps581G distribution in these areas needs to be collected to guide IPTp-SP recommendations. Prevalence and uncertainty maps can be utilized together to strategically identify sites where increased surveillance can be most informative. This study combines a molecular marker database and predictive modelling to highlight areas of concern, which can be used to support decisions in public health, highlight knowledge gaps in certain regions, and guide future research.     

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.