Extracellular addition of a domain of HIV-1 Vpr containing the amino acid sequence motif H(S/F)RIG causes cell membrane permeabilization and death

Vpr is a virion-associated protein of human immuno-deficiency virus type 1 (HIV-1) whose function in acquired immune deficiency syndrome (AIDS) has been uncertain. We previously employed yeast as a model to examine the effects of Vpr on basic cellular functions; intracellular Vpr was shown to cause cell-growth arrest and structural defects, and these effects were caused by a region of Vpr containing the sequence HFRIGCRHSRIG. Here we show that peptides containing the H(S/F)RIG amino acid sequence motif cause death when added externally to a variety of yeast including Saccharomyces cerevisiae, Kluyveromyces lactis, Candida glabrata, Candida albicans and Schizosaccharomyces pombe. Such peptides rapldly entered the cell from the time of addition, resulting in cell death. Elevated levels of ions, particularly magnesium and calcium ions, abrogated the cytotoxic effect by preventing the Vpr peptides from entering the cells. Extracellular Vpr found in the serum, or breakdown products of extracellular Vpr, may have similar effects to the Vpr peptides described here and could explain the death of uninfected by-stander cells during AIDS.     

Genetic and paleomodelling evidence of the population expansion of the cattle egret Bubulcus ibis in Africa during the climatic oscillations of the Late Pleistocene

Increasing aridity during glacial periods produced the retraction of forests and the expansion of arid and semi‐arid environments in Africa, with consequences for birds. Cattle egret Bubulcus ibis is a dispersive species that prefers semi‐arid environments and requires proximity to bodies of water. We expected that climatic oscillations led to the expansion of the range of the cattle egret during arid periods, such as the Last Maximum Glacial (LGM) and contraction of distribution during the Last Interglacial (LIG) period, resulting in contact of populations previously isolated. We investigated this hypothesis by evaluating the genetic structure and population history of 15 cattle egret breeding colonies located in west and South Africa using the mitochondrial DNA (mtDNA) control region, mtDNA ATPase 8 and 6, and an intron of nuclear gene transforming growth factor‐beta 2. Occurrence data and bioclimatic information were used to generate ecological niche models of three periods (present, LGM and LIG). We used the genetic and paleomodelling data to assess the responses of the cattle egret from Africa to the climatic oscillations during the late Pleistocene. Genetic data revealed low levels of genetic differentiation, signs of isolation‐by‐distance, as well as recent increases in effective population size that started during the LGM. The observed low genetic structure may be explained by recent colonization events due to the demographic expansion following the last glacial period and by dispersal capacity of this species. The paleomodels corroborated the expansion during the LGM, and a more restricted potential distribution during the LIG. Our findinds supports the hypothesis that the species range of the cattle egret expanded during arid periods and contracted during wet periods.     

Effects of climate variability on the demography of wild geladas

Nonhuman primates are an essential part of tropical biodiversity and play key roles in many ecosystem functions, processes, and services. However, the impact of climate variability on nonhuman primates, whether anthropogenic or otherwise, remains poorly understood. In this study, we utilized age‐structured matrix population models to assess the population viability and demographic variability of a population of geladas (Theropithecus gelada) in the Simien Mountains, Ethiopia with the aim of revealing any underlying climatic influences. Using data from 2008 to 2019 we calculated annual, time‐averaged, and stochastic population growth rates (λ) and investigated relationships between vital rate variability and monthly cumulative rainfall and mean temperature. Our results showed that under the prevailing environmental conditions, the population will increase (λ _s = 1.021). Significant effects from rainfall and/or temperature variability were widely detected across vital rates; only the first year of infant survival and the individual years of juvenile survival were definitively unaffected. Generally, the higher temperature in the hot‐dry season led to lower survival and higher fecundity, while higher rainfall in the hot‐dry season led to increased survival and fecundity. Overall, these results provide evidence of greater effects of climate variability across a wider range of vital rates than those found in previous primate demography studies. This highlights that although primates have often shown substantial resilience to the direct effects of climate change, their vulnerability may vary with habitat type and across populations.     

Reproductive characteristics of wild female Phayre's leaf monkeys

Understanding female reproductive characteristics is important for assessing fertility, interpreting female behavior, and designing appropriate conservation and captive management plans. In primate species lacking morphological signs of receptivity, such as most colobines, determination of reproductive parameters depends on the analysis of reproductive hormones. Here, we use fecal hormone analysis to characterize cycle patterns (N=6 females) and gestation length (N=7 females) in a group of wild Phayre's leaf monkeys (Trachypithecus phayrei crepusculus) in Phu Khieo Wildlife Sanctuary, Thailand. We found that both fecal estrogen (fE) and progestin (fP) levels showed clear biological patterns indicative of ovulation and conception. However, because fP patterns were inadequate in determining the end of the luteal phase, we used fE rather than fP patterns to delineate menstrual cycle parameters. We found a mean cycle length of 28.4 days (N=10), with follicular and luteal phases of 15.4 (N=10) and 12.5 days (N=14), respectively. On average, females underwent 3.57 (N=7) cycles until conception. Average gestation length was 205.3 days (N=7), with fE levels increasing over the course of pregnancy. Overall, the reproductive characteristics found for Phayre's leaf monkeys were consistent with results for other colobine species, suggesting that fecal hormone monitoring, particularly for fE metabolites, can provide useful reproductive information for this species. Am. J. Primatol. 72:1073–1081, 2010. © 2010 Wiley‐Liss, Inc.     

Expression of HIV-1nefin yeast causes membrane perturbation and release of the myristylated Nef protein

The human immunodeficiency virus type 1 (HIV-1) Nef protein is essential for AIDS pathogenesis, but its function remains highly controversial. During stresses such as growth in the presence of copper or at elevated temperature, myristylated Nef is released from yeast cells and, after extended culture in stationary phase, it accumulates in the supernatant as a dense membranous material that can be centrifuged into a discrete layer above the cell pellet. This material is unique to Nef-producing cells and represents a convenient source of Nef that may have application in further biological studies. Within the yeast cell, electron microscopic examination shows that Nef localises in novel, membrane-bound bodies. These data support the evidence for a role of Nef in membrane perturbation and suggest that there may be a similar localisation for myristylated Nef in HIV-1 infected cells.     

Testing extraction and storage parameters for a fecal hormone method

Four experiments were conducted to test different aspects of a “field‐friendly” fecal hormone extraction method that utilizes methanol extraction in the field followed by storage on C18 solid‐phase extraction cartridges. Fecal samples were collected from geladas (Theropithecus gelada) housed at the Bronx Zoo, and the experiments were conducted in a laboratory setting to ensure maximum control. The experiments were designed to either simulate the conditions to which fecal samples are subjected during fieldwork or improve on an existing protocol. The experiments tested the relationship between fecal hormone metabolite preservation/recovery and: (1) the amount of time a sample is stored at ambient temperature; (2) the number of freeze/thaw cycles a sample undergoes; (3) the effectiveness of different extraction solutions; and (4) the effectiveness of different cartridge washes. For each experiment, samples were assayed by radioimmunoassay for fecal glucocorticoid (GC) and testosterone (T) metabolites. Results for each of the experiments were as follows. First, storage at ambient temperature did not affect hormone levels until 4 weeks of storage, with significant increases for both GC and T metabolites at 4 weeks. Second, hormone levels significantly decreased in samples after two freeze/thaw cycles for GCs and six freeze/thaws cycles for T. Third, for both GCs and T, hormone extraction using various methanol solutions was significantly higher than using 100% ethanol. Finally, using a 20% methanol solution to wash cartridges significantly increased GC levels but had no effect on T levels. These results suggest that, when utilizing C18 cartridges for fecal steroid storage, researchers should consider several methodological options to optimize hormone preservation and recovery from fecal samples. Am. J. Primatol. 72:934–941, 2010. © 2010 Wiley‐Liss, Inc.     

Determination of protein complex stoichiometry through multisignal sedimentation velocity experiments

Determination of the stoichiometry of macromolecular assemblies is fundamental to an understanding of how they function. Many different biophysical methodologies may be used to determine stoichiometry. In the past, both sedimentation equilibrium and sedimentation velocity analytical ultracentrifugation have been employed to determine component stoichiometries. Recently, a method of globally analyzing multisignal sedimentation velocity data was introduced by Schuck and coworkers. This global analysis removes some of the experimental inconveniences and inaccuracies that could occur in the previously used strategies. This method uses spectral differences between the macromolecular components to decompose the well-known c(s) distribution into component distributions c_k(s); that is, each component k has its own c_k(s) distribution. Integration of these distributions allows the calculation of the populations of each component in cosedimenting complexes, yielding their stoichiometry. In our laboratories, we have used this method extensively to determine the component stoichiometries of several protein-protein complexes involved in cytoskeletal remodeling, sugar metabolism, and host-pathogen interactions. The overall method is described in detail in this work, as are experimental examples and caveats.     

Fimbriae of uropathogenic Proteus mirabilis

Proteus mirabilis is a common causative agent of cystitis and pyelonephritis in patients with urinary catheters or structural abnormalities of the urinary tract. Several types of fimbriae, which are potentially involved in adhesion to the uroepithelium, can be expressed simultaneously by P. mirabilis: mannose-resistant/Proteus-like (MR/P) fimbriae, P. mirabilis fimbriae (PMF), uroepithelial cell adhesin (UCA), renamed by some authors nonagglutinating fimbriae (NAF), and ambient-temperature fimbriae (ATF). Proteus mirabilis is a common cause of biofilm formation on catheter material and MR/P fimbriae are involved in this process. The considerable serious pathology caused by P. mirabilis in the urinary tract warrants the development of a prophylactic vaccine, and several studies have pointed to MR/P fimbriae as a potential target for immunization. This article reviews P. mirabilis fimbriae with regard to their participation in uropathogenesis, biofilm formation and as vaccine targets.     

IL-12Rβ1 deficiency in two of fifty children with severe tuberculosis from Iran, Morocco, and Turkey

Background and Objectives

In the last decade, autosomal recessive IL-12Rβ1 deficiency has been diagnosed in four children with severe tuberculosis from three unrelated families from Morocco, Spain, and Turkey, providing proof-of-principle that tuberculosis in otherwise healthy children may result from single-gene inborn errors of immunity. We aimed to estimate the fraction of children developing severe tuberculosis due to IL-12Rβ1 deficiency in areas endemic for tuberculosis and where parental consanguinity is common.

Methods and Principal Findings

We searched for IL12RB1 mutations in a series of 50 children from Iran, Morocco, and Turkey. All children had established severe pulmonary and/or disseminated tuberculosis requiring hospitalization and were otherwise normally resistant to weakly virulent BCG vaccines and environmental mycobacteria. In one child from Iran and another from Morocco, homozygosity for loss-of-function IL12RB1 alleles was documented, resulting in complete IL-12Rβ1 deficiency. Despite the small sample studied, our findings suggest that IL-12Rβ1 deficiency is not a very rare cause of pediatric tuberculosis in these countries, where it should be considered in selected children with severe disease.

Significance

This finding may have important medical implications, as recombinant IFN-γ is an effective treatment for mycobacterial infections in IL-12Rβ1-deficient patients. It also provides additional support for the view that severe tuberculosis in childhood may result from a collection of single-gene inborn errors of immunity.