TRIM5 Suppresses Cross-Species Transmission of a Primate Immunodeficiency Virus and Selects for Emergence of Resistant Variants in the New Species

Simian immunodeficiency viruses of sooty mangabeys (SIVsm) are the source of multiple, successful cross-species transmissions, having given rise to HIV-2 in humans, SIVmac in rhesus macaques, and SIVstm in stump-tailed macaques. Cellular assays and phylogenetic comparisons indirectly support a role for TRIM5α, the product of the TRIM5 gene, in suppressing interspecies transmission and emergence of retroviruses in nature. Here, we investigate the in vivo role of TRIM5 directly, focusing on transmission of primate immunodeficiency viruses between outbred primate hosts. Specifically, we retrospectively analyzed experimental cross-species transmission of SIVsm in two cohorts of rhesus macaques and found a significant effect of TRIM5 genotype on viral replication levels. The effect was especially pronounced in a cohort of animals infected with SIVsmE543-3, where TRIM5 genotype correlated with approximately 100-fold to 1,000-fold differences in viral replication levels. Surprisingly, transmission occurred even in individuals bearing restrictive TRIM5 genotypes, resulting in attenuation of replication rather than an outright block to infection. In cell-culture assays, the same TRIM5 alleles associated with viral suppression in vivo blocked infectivity of two SIVsm strains, but not the macaque-adapted strain SIVmac239. Adaptations appeared in the viral capsid in animals with restrictive TRIM5 genotypes, and similar adaptations coincide with emergence of SIVmac in captive macaques in the 1970s. Thus, host TRIM5 can suppress viral replication in vivo, exerting selective pressure during the initial stages of cross-species transmission.     

Tests for heritable genetic damage and for evidence of gonadal exposure in mammals

Tests for the induction of genetic damage in mammalian germ cells provide the data needed for human genetic risk assessment and are used as standards for judging the ability of shorter-term tests to predict genetic hazard. In this review, 15 mammalian germ-cell tests and their variants are described. These tests are of two general types: (a) those designed to detect certain classes of genetic damage (gene mutations, chromosome breakage and/or rearrangement, and chromosome mis-segregation), regardless of whether or not the endpoint scored has any significance to human health, and (b) those designed to detect phenotypes that have human health implications, while the nature of the genetic damage is not usually known. Exposure to a mutagenic agent presents no genetic hazard if the chemical or its metabolites fail to reach the reproductive cells. Tests for gonadal exposure are, therefore, important, as preliminaries or components of studies on germ-cell mutagenicity. Seven of these tests and their variants are briefly described in the second part of the paper.     

Pheromone trap for the eastern tent caterpillar moth

The discovery that the eastern tent caterpillar Malacosoma americanum (F.) causes mare reproductive loss syndrome (MRLS), and thus has the potential to continue to result in major economic losses to the equine industry of Kentucky, has resulted in an intensive effort to identify practical means to monitor and control this defoliator, including these experiments to optimize a sex pheromone trap for this pest. A pheromone-baited delta trap with a large opening, such as InterceptST Delta, was more effective than other tested traps. Orange delta traps caught more moths than other tested colors. ETC males are caught at all tested heights within the tree canopy. For monitoring flights, setting traps at 1.5 m would allow easy counting of moths. A 9:1 blend of (E,Z)-5,7-dodecadienal (ETC-Ald) and (E,Z)-5,7-dodecadienol (ETC-OH) was most effective in capturing males. Increasing loading doses of a 3:1 blend (Ald:OH) resulted in the capture of increasing numbers of moths, but a 9:1 blend was more effective than 3:1 blend even at a nine-fold lower loading rate. Pheromone-impregnated white septa caught more moths than gray septa at the same loading dose. The advantages and limitations of using pheromone traps for monitoring M. americanum are discussed.     

Dynamic Regulation of Fluorescent Proteins from a Single Species of Coral

To gain a better understanding of the natural function of fluorescent proteins, we have undertaken quantitative analyses of these proteins in a single species of coral, Montastraea cavernosa, residing around Turneffe atoll, on the Belizean Barrier Reef. We identified at least 10 members of a fluorescent protein family in this species, which consist of 4 distinct spectral classes. As much as a 10-fold change in the overall expression of fluorescent proteins was observed from specimen to specimen, suggesting that fluorescent proteins are dynamically regulated in response to environmental or physiological conditions. We found that the expression of some proteins was inversely correlated with depth, and that groups of proteins were coordinately expressed. There was no relationship between the expression of fluorescent proteins and the natural coloration of the Montastraea cavernosa specimens in this study. These findings have implications for current hypotheses regarding the properties and natural function of fluorescent proteins.     

Chemical defense by the native winter ant (Prenolepis imparis) against the invasive Argentine ant (Linepithema humile)

The invasive Argentine ant (Linepithema humile) is established worldwide and displaces native ant species. In northern California, however, the native winter ant (Prenolepis imparis) persists in invaded areas. We found that in aggressive interactions between the two species, P. imparis employs a potent defensive secretion. Field observations were conducted at P. imparis nest sites both in the presence and absence of L. humile. These observations suggested and laboratory assays confirmed that P. imparis workers are more likely to secrete when outnumbered by L. humile. Workers of P. imparis were also more likely to secrete near their nest entrances than when foraging on trees. One-on-one laboratory trials showed that the P. imparis secretion is highly lethal to L. humile, causing 79% mortality. The nonpolar fraction of the secretion was chemically analyzed with gas chromatography/mass spectrometry, and found to be composed of long-chain and cyclic hydrocarbons. Chemical analysis of dissected P. imparis workers showed that the nonpolar fraction is derived from the Dufour's gland. Based on these conclusions, we hypothesize that this chemical defense may help P. imparis to resist displacement by L. humile.     

Alginate Hydrogels for Three-Dimensional Organ Culture of Ovaries and Oviducts

Ovarian cancer is the fifth leading cause of cancer deaths in women and has a 63% mortality rate in the United States¹. The cell type of origin for ovarian cancers is still in question and might be either the ovarian surface epithelium (OSE) or the distal epithelium of the fallopian tube fimbriae^2,3. Culturing the normal cells as a primary culture in vitro will enable scientists to model specific changes that might lead to ovarian cancer in the distinct epithelium, thereby definitively determining the cell type of origin. This will allow development of more accurate biomarkers, animal models with tissue-specific gene changes, and better prevention strategies targeted to this disease.Maintaining normal cells in alginate hydrogels promotes short term in vitro culture of cells in their three-dimensional context and permits introduction of plasmid DNA, siRNA, and small molecules. By culturing organs in pieces that are derived from strategic cuts using a scalpel, several cultures from a single organ can be generated, increasing the number of experiments from a single animal. These cuts model aspects of ovulation leading to proliferation of the OSE, which is associated with ovarian cancer formation. Cell types such as the OSE that do not grow well on plastic surfaces can be cultured using this method and facilitate investigation into normal cellular processes or the earliest events in cancer formation⁴.Alginate hydrogels can be used to support the growth of many types of tissues⁵. Alginate is a linear polysaccharide composed of repeating units of β-D-mannuronic acid and α-L-guluronic acid that can be crosslinked with calcium ions, resulting in a gentle gelling action that does not damage tissues^6,7. Like other three-dimensional cell culture matrices such as Matrigel, alginate provides mechanical support for tissues; however, proteins are not reactive with the alginate matrix, and therefore alginate functions as a synthetic extracellular matrix that does not initiate cell signaling⁵. The alginate hydrogel floats in standard cell culture medium and supports the architecture of the tissue growth in vitro.A method is presented for the preparation, separation, and embedding of ovarian and oviductal organ pieces into alginate hydrogels, which can be maintained in culture for up to two weeks. The enzymatic release of cells for analysis of proteins and RNA samples from the organ culture is also described. Finally, the growth of primary cell types is possible without genetic immortalization from mice and permits investigators to use knockout and transgenic mice.Download video file.^{(42M, mov)}     

Targeted disruption of p53 attenuates doxorubicin-induced cardiac toxicity in mice

Use of the chemotherapeutic agent doxorubicin (Dox) is limited by dose-dependent cardiotoxic effects. The molecular mechanism underlying these toxicities are incompletely understood, but previous results have demonstrated that Dox induces p53 expression. Because p53 is an important regulator of the cell birth and death we hypothesized that targeted disruption of the p53 gene would attenuate Dox-induced cardiotoxicity. To test this, female 6–8 wk old C57BL wild-type (WT) or p53 knockout (p53 KO) mice were randomized to either saline or Dox 20 mg/kg via intraperitoneal injection. Animals were serially imaged with high-frequency (14 MHz) two-dimensional echocardiography. Measurements of left ventricle (LV) systolic function as assessed by fractional shortening (FS) demonstrated a decline in WT mice as early as 4 days after Dox injection and by 2 wk demonstrated a reduction of 31± 16% (P < 0.05) from the baseline. In contrast, in p53 KO mice, LV FS was unchanged over the 2 wk period following Dox injection. Apoptosis of cardiac myocytes as measured by the TUNEL and ligase reactions were significantly increased at 24 h after Dox treatment in WT mice but not in p53 KO mice. After Dox injection, levels of myocardial glutathione and Cu/Zn superoxide dismutase were preserved in p53 KO mice, but not in WT animals. These observations suggest that p53 mediated signals are likely to play a significant role in Dox-induced cardiac toxicity and that they may modulate Dox-induced oxidative stress.These two authors equally contributed to this study.     

Recombinant NhSAG1 ELISA: a sensitive and specific assay for detecting antibodies against Neospora hughesi in equine serum

Neospora hughesi is a recently identified cause of equine protozoal myeloencephalitis. However, the significance of this parasite is poorly understood. An enzyme-linked immunosorbent assay (ELISA) with a recombinant form of the N. hughesi 29-kDa surface antigen (rNhSAG1) was developed for serodiagnosis of equine N. hughesi infections. Parallel ELISA analysis showed that animals immunized or infected with N. hughesi exhibited greater antibody reactivity with rNhSAG1 than with the Neospora caninum homolog, rNcSAG1. The rNhSAG1 ELISA showed 94.4% sensitivity and 95.0% specificity when compared with N. hughesi western blot results for 1,006 samples. The N. hughesi seroprevalence was 3.4% for the 1,917 samples tested by ELISA, which is less than earlier reports. Importantly, western blot analysis of ELISA-positive sera revealed only 18 true seropositive samples for an even lower seroprevalence of 0.9%. These results imply that Neospora spp. infections are uncommon in horses. The sensitivity and specificity exhibited by the rNhSAG1 ELISA suggest that it has a potential use for serodiagnosis of N. hughesi infection in equids. Furthermore, the high-throughput capability of the ELISA will allow for screening large sample sets, which should provide a better understanding of N. hughesi epidemiology.     

Transmitted mutational events induced in mouse germ cells following acrylamide or glycidamide exposure

An increase in the germ line mutation rate in humans will result in an increase in the incidence of genetically determined diseases in subsequent generations. Thus, it is important to identify those agents that are mutagenic in mammalian germ cells. Acrylamide is water soluble, absorbed and distributed in the body, chemically reactive with nucleophilic sites, and there are known sources of human exposure. Here we review all seven published studies that assessed the effectiveness of acrylamide or its active metabolite, glycidamide, in inducing transmitted reciprocal translocations or gene mutations in the mouse. Major conclusions were (a) acrylamide is mutagenic in spermatozoa and spermatid stages of the male germ line; (b) in these spermatogenic stages acrylamide is mainly or exclusively a clastogen; (c) per unit dose, i.p. exposure is more effective than dermal exposure; and (d) per unit dose, glycidamide is more effective than acrylamide. Since stem cell spermatogonia persist and may accumulate mutations throughout the reproductive life of males, assessment of induced mutations in this germ cell stage is critical for the assessment of genetic risk associated with exposure to a mutagen. The two specific-locus mutation experiments which studied the stem cell spermatogonial stage yielded conflicting results. This discrepancy should be resolved. Finally, it is noted that no experiments have studied the mutagenic potential of acrylamide to increase the frequency of transmitted mutational events following exposure in the female germ line.