Inactivation of human immunodeficiency virus type 1 in blood samples stored as high-salt lysates

Blood samples to be tested for the presence of parasite DNA by using specific DNA probes are routinely stored in our laboratory as high-salt lysates (HSL). To safeguard against the risk of accidental infection with etiological agents such as the human immunodeficiency virus type 1 (HIV-1) while manipulating large numbers of blood samples in preparation for DNA probing, we determined the residual infectivity of HIV-1 after exposure to HSL components. Both high-titer virus stocks or provirus-carrying cells, suspended either in tissue culture medium or freshly drawn blood, were completely inactivated upon contact with the HSL components. This was verified by the absence of any detectable HIV-1-specific antigen in the supernatants of long-term cultures and the absence of virus-specific DNA fragments after amplification by polymerase chain reaction with DNA from such cultures as target DNA. These results support the conclusion that the virus is in fact completely inactivated by contact with the HSL components, rendering blood specimens stored as HSL noninfectious in regard to HIV-1.     

Effect of sonication on paraffin-embedded tissue preparation for DNA flow cytometry

Since the publication of paraffin block extraction procedures, flow cytometric analysis of DNA ploidy and S-phase of tumor specimens has been widely applied. DNA aneuploidy, DNA tetraploid (elevated G2/M), and elevated S-phase are clinically significant in some tumor systems. True DNA tetraploid cell lines will contain a large 4c population and perhaps an 8c population; samples with cell aggregates will also contain a 6c population. Microscopic examination of samples having a 6c peak revealed nuclei with adhering debris and doublets, triplets, and larger nuclear aggregates. After sonication, a uniform suspension of single nuclei without adherent debris was seen. In addition to reducing the percent of G2/M cells, sonication also reduced S-phase percent such that it was closer to the bromodeoxyuridine labeling index. The DNA ploidy classification of specimens was also compared pre- and post-sonication. Four of 96 breast cancer samples changed classification; all were specimens in which the histogram became cleaner and a small DNA aneuploid peak became apparent after sonication.     

Spectral resolution of cardio-circulatory variations in men measured by autorhythmometry over 2 years

An analogue of the periodogram method for unequally spaced data is presented with a view to resolving the frequency structure of the observations. The algorithm is explicitly based on the sequential least squares procedure. In particular, the key concept is that the with-in-plot spectral analysis can be augmented by the between-plot information to make inferences about common characteristics. It is also shown how the between-plot random variations can be incorporated into the multiple harmonic regression model. A detailed spectral analysis investigates the periodic fluctuations in four cardio-circulatory variables, measured by autorhythmometric observation by eight men at rest and extending over a time span of 2 years. The spectral curves show the existence of circadian and circaseptan rhythmicities. The amplitude modulation of the dian rhythm by circaseptan variation is assimilated with the rhythmicity of work during the week. The blood-pressure variables situate their maximum annual peak in the winter period. These quasi-periodic fluctuations appear to be related to the amount of physical activity performed in time by the subjects.     

Shedding of Endogenous Interleukin-6 Receptor (IL-6R) Is Governed by A Disintegrin and Metalloproteinase (ADAM) Proteases while a Full-length IL-6R Isoform Localizes to Circulating Microvesicles

Generation of the soluble interleukin-6 receptor (sIL-6R) is a prerequisite for pathogenic IL-6 trans-signaling, which constitutes a distinct signaling pathway of the pleiotropic cytokine interleukin-6 (IL-6). Although in vitro experiments using ectopically overexpressed IL-6R and candidate proteases revealed major roles for the metalloproteinases ADAM10 and ADAM17 in IL-6R shedding, the identity of the protease(s) cleaving IL-6R in more physiological settings, or even in vivo, remains unknown. By taking advantage of specific pharmacological inhibitors and primary cells from ADAM-deficient mice we established that endogenous IL-6R of both human and murine origin is shed by ADAM17 in an induced manner, whereas constitutive release of endogenous IL-6R is largely mediated by ADAM10. Although circulating IL-6R levels are altered in various diseases, the origin of blood-borne IL-6R is still poorly understood. It has been shown previously that ADAM17 hypomorphic mice exhibit unaltered levels of serum sIL-6R. Here, by quantification of serum sIL-6R in protease-deficient mice as well as human patients we also excluded ADAM10, ADAM8, neutrophil elastase, cathepsin G, and proteinase 3 from contributing to circulating sIL-6R. Furthermore, we ruled out alternative splicing of the IL-6R mRNA as a potential source of circulating sIL-6R in the mouse. Instead, we found full-length IL-6R on circulating microvesicles, establishing microvesicle release as a novel mechanism for sIL-6R generation.     

Bacteriophage-resistance mechanisms examined by transfection of Lactococcus lactis subsp. lactis 4513-5 mediated by high voltage electroporation

Summary Phage adsorption tests and transfection by electroporation were carried out to decide whether phage-resistance in Lactococcus lactis subsp. lactis strain 4513-5 is based on intracellular or extracellular mechanisms. Using high voltage (12.5 kV/cm) electroporation, untreated phage DNA was introduced into phage-sensitive and phage-resistant cells. Since phages showed low adsorption frequencies on resistant bacteria, resistance is localized in the cell wall preventing phage DNA from entering the cell. This is the only mechanism responsible for the resistance of L. lactis subsp. lactis 4513-5 against its homologous phage P4513-K12 and non-homologous phages P05M-13 and P05M-47, but not against phage P530-7 and phage P530-12. In the case of the latter two phage strains, intracellular resistance mechanisms are involved and discussed.     

The Dpy-30 Gene Encodes an Essential Component of the Caenorhabditis Elegans Dosage Compensation Machinery

The need to regulate X chromosome expression in Caenorhabditis elegans arises as a consequence of the primary sex-determining signal, the X/A ratio (the ratio of X chromosomes to sets of autosomes), which directs 1X/2A animals to develop as males and 2X/2A animals to develop as hermaphrodites. C. elegans possesses a dosage compensation mechanism that equalizes X chromosome expression between the two sexes despite their disparity in X chromosome dosage. Previous genetic analysis led to the identification of four autosomal genes, dpy-21, dpy-26, dpy-27 and dpy-28, whose products are essential in XX animals for proper dosage compensation, but not for sex determination. We report the identification and characterization of dpy-30, an essential component of the dosage compensation machinery. Putative null mutations in dpy-30 disrupt dosage compensation and cause a severe maternal-effect, XX-specific lethality. Rare survivors of the dpy-30 lethality are dumpy and express their X-linked genes at higher than wild-type levels. These dpy-30 mutant phenotypes superficially resemble those caused by mutations in dpy-26, dpy-27 and dpy-28; however, detailed phenotypic analysis reveals important differences that distinguish dpy-30 from these genes. In contrast to the XX-specific lethality caused by mutations in the other dpy genes, the XX-specific lethality caused by dpy-30 mutations is completely penetrant and temperature sensitive. In addition, unlike the other genes, dpy-30 is required for the normal development of XO animals. Although dpy-30 mutations do not significantly affect the viability of XO animals, they do cause them to be developmentally delayed and to possess numerous morphological and behavioral abnormalities. Finally, dpy-30 mutations can dramatically influence the choice of sexual fate in animals with an ambiguous sexual identity, despite having no apparent effect on the sexual phenotype of otherwise wild-type animals. Paradoxically, depending on the genetic background, dpy-30 mutations cause either masculinization or feminization, thus revealing the complex regulatory relationship between the sex determination and dosage compensation processes. The novel phenotypes caused by dpy-30 mutations suggest that in addition to acting in the dosage compensation process, dpy-30 may play a more general role in the development of both XX and XO animals.     

Somatic polyploidy in extraembryonic membranes of the snake,Elaphe guttata

Summary Video-densitometric DNA measurements of Feulgenstained tissues of 42 day old eggs of the corn snake,Elaphe g. guttata (Columbridae, Serpentes), revealed a basic DNA content of 2C=2.17 pg, with somatic polyploidy in the allantois, the chorioallontois, the yolk sac, and other extraembryonic membranes. The maximum value determined was 128C (in binucleate cells 2×128C) at the distal pole of the egg. This is the first report of somatic polyploidy in a snake, and one of the first in reptiles in general.     

Butterfly Response to Microclimatic Conditions Following Ponderosa Pine Restoration

Efforts to restore ponderosa pine ecosystems to open, park‐like conditions that predominated prior to European‐American settlement result in altered stand structure and increased landscape heterogeneity, potentially altering habitat suitability for invertebrates and other forest organisms. We examined the responses of two butterfly species, Colias eurytheme and Neophasia menapia, to microclimatic changes at structural edges created by experimental restoration treatments in northern Arizona. We monitored microclimate, including air temperature, light intensity, and vapor pressure deficit (VPD), on several mornings during butterfly releases. We placed adult butterflies at east‐ and west‐facing edges approximately one half‐hour before dawn to determine their behavioral response to microclimatic differences between east‐ and west‐facing edges. After sunrise, all three microclimatic variables were higher at east‐facing edges, and the difference in microclimate between the two edge orientations increased through early morning. For both species, butterflies placed at east‐facing edges flew earlier than butterflies at west‐facing edges. Colias eurytheme, an open‐habitat species, tended to move toward the treated forest during initial flight, while movements of Neophasia menapia, a forest‐dwelling species, did not differ from random flight. Our results indicate that butterflies respond to microclimatic factors associated with restoration treatments, while responses to structural changes in habitat vary among species, based on habitat and food plant preferences. These changes in forest structure and microclimate may affect the distribution of many mobile invertebrates in forested landscapes undergoing restoration treatments.     

An invasive tree alters the structure of seed dispersal networks between birds and plants in French Polynesia

Aim We studied how the abundance of the highly invasive fruit‐bearing tree Miconia calvescens DC. influences seed dispersal networks and the foraging patterns of three avian frugivores. Location Tahiti and Moorea, French Polynesia. Methods Our study was conducted at six sites which vary in the abundance of M. calvescens. We used dietary data from three frugivores (two introduced, one endemic) to determine whether patterns of fruit consumption are related to invasive tree abundance. We constructed seed dispersal networks for each island to evaluate how patterns of interaction between frugivores and plants shift at highly invaded sites. Results Two frugivores increased consumption of M. calvescens fruit at highly invaded sites and decreased consumption of other dietary items. The endemic fruit dove, Ptilinopus purpuratus, consumed more native fruit than either of the two introduced frugivores (the red‐vented bulbul, Pycnonotus cafer, and the silvereye, Zosterops lateralis), and introduced frugivores showed a low potential to act as dispersers of native plants. Network patterns on the highly invaded island of Tahiti were dominated by introduced plants and birds, which were responsible for the majority of plant–frugivore interactions. Main conclusions Shifts in the diet of introduced birds, coupled with reduced populations of endemic frugivores, caused differences in properties of the seed dispersal network on the island of Tahiti compared to the less invaded island of Moorea. These results demonstrate that the presence of invasive fruit‐bearing plants and introduced frugivores can alter seed dispersal networks, and that the patterns of alteration depend both on the frugivore community and on the relative abundance of available fruit.