Variation in demographic patterns and population structure of raccoons across an urban landscape

Raccoons (Procyon lotor) are considered synanthropic, with high densities reported from urban landscapes. However, little information is available on population density and demography within the urban matrix. To better understand how urban land-use patterns influence raccoon density and demographic patterns, we sampled raccoons at multiple, replicated sites across an urban landscape. Density differed by land-use type (F_2,17 = 4.66, P = 0.027): urbanized sites, = 4.96 ± 2.64 raccoons/km², range = 1.25–10.00 raccoons/km²; urban open sites, = 14.84 ± 6.35 raccoons/km², range = 3.00–29.25 raccoons/km²; rural open sites, = 15.50 ± 4.66 raccoons/km², range = 13.00–20.25. Although we found no clear patterns in sex ratio, reproductive condition, or body condition, we observed differences in age structure among urban open, rural open, and urbanized sites. The most striking difference was the absence of older animals at urbanized sites and relatively low numbers of young individuals at urban open sites. Raccoons were the dominant mesocarnivore in open fragments, but less so in the urban matrix. Spatial variation in density across urban landscapes is likely influenced by site level differences in abundance of anthropogenic resources and differences in habitat quality. Furthermore, the association between changes in land-use and population age structure may have reflected different mortality sources across the landscape. Our results illustrate that wildlife species considered synanthropic may have complex relationships with urban landscapes. © 2012 The Wildlife Society.     

Spatial Ecology of Raccoons Related to Cattle and Bovine Tuberculosis in Northeastern Michigan

ABSTRACT In 1995, Mycobacterium bovis, the causative bacterium of bovine tuberculosis (bTB), was detected in 5 beef cattle operations in Alcona County, Michigan, USA. In accordance with Federal law, the operations were depopulated to prevent the spread of bTB. Subsequent wildlife surveillance programs identified high prevalence of M. bovis in mesocarnivores, including raccoons (Procyon lotor), which suggested that raccoons may be complicit in vectoring the pathogen among livestock operations. Our goal was to develop an empirical basis for generating hypotheses about the likelihood for raccoons to mediate the transmission of bTB to livestock. We found intersexual differences in scale-dependent resource selection and probability of spatial interaction that, under certain circumstances, may form the foundation for a sex-bias in disease transmission. Spatial dispersion of mixed-forest patches facilitated overlap of adjacent males, whereas female overlap zones included pastures. Within overlap zones, probabilities of interaction for male-male and male-female dyads were greater than for female-female dyads, although we documented an elevated likelihood of spatial interaction between raccoons and livestock around cattle-feeding troughs and water sources, regardless of sex. Partial regressions generated by linear models indicated that distance between nearest-neighbor mixed-forest patches explained most of this observed variation. These results supported our prediction that forest patches juxtaposed with anthropogenic features fostered social tolerance between males and, thus, facilitated spatial interaction and exploitation of anthropogenic features. In raccoons, sex and landscape composition influenced pathogen transmission potential. We suggest that livestock producers locate livestock feeding and watering features away from forest patches to mitigate future outbreaks of bTB in endemic areas.     

Effects of Natural Barriers and Habitat on the Western Spread of Raccoon Rabies in Alabama

Abstract: Although domestic animal transmission of rabies has largely been mitigated, the disease remains a concern in both Europe and North America where wildlife transmission has caused epizootics. Raccoon (Procyon lotor) rabies was established in Alabama, USA, in 1975, primarily in the southeastern corner of the state. However, with the exception of isolated events, rabies has not continued to spread westward across the Alabama River. We monitored movements of 100 radiocollared raccoons on 2 sites within hardwood and agriculture habitats in a rabies enzootic area east of the Alabama River, in managed pine habitat area west of the river where rabies sporadically occurs, and in a mixed pine hardwood area outside of the known rabies enzootic area to determine if raccoon movements and habitat use in certain habitat types and the presence of a river may serve as natural barriers preventing the western spread of rabies in Alabama. We also examined raccoon contact rates to determine if they influence disease transmission through static and dynamic interactions. Raccoons in mixed pine-hardwood forest habitats had smaller home ranges and less overlap of ranges compared to the other 3 habitats. However, static interactions between habitats in the use of overlap areas did not differ (F_11,129 = 1.63, P = 0.09). Rabies antibody titers were highest in the managed pine habitat (28%) even prior to oral vaccine bait distributions in spring of 2004 and 2005. Biomarker data from radiocollared and additional raccoons captured after the bait distribution west of the Alabama River demonstrated a low efficacy of the vaccine reaching the small southern raccoons. The combination of the river as a partial barrier, the high percentage of pine forested habitat west of the river, and limited spatial movements of raccoons within these forested habitats appears to have reduced the likelihood of rabies establishing west of the river. Understanding different host-habitat- disease systems is important for successful management of diseases. Based on our results, we recommend that the oral vaccine program continue to use the Alabama River as a partial barrier and baiting be concentrated in the fragmented bottomland hardwood forests and around larger bodies of water where raccoon densities are highest. Success of baiting strategies designed to take advantage of northern raccoon dynamics and habitat use may not be applicable to southern populations.     

Spatial patterns of neutral and functional genetic variations reveal patterns of local adaptation in raccoon (Procyon lotor) populations exposed to raccoon rabies

Local adaptation is necessary for population survival and depends on the interplay between responses to selective forces and demographic processes that introduce or retain adaptive and maladaptive attributes. Host–parasite systems are dynamic, varying in space and time, where both host and parasites must adapt to their ever‐changing environment in order to survive. We investigated patterns of local adaptation in raccoon populations with varying temporal exposure to the raccoon rabies virus (RRV). RRV infects approximately 85% of the population when epizootic and has been presumed to be completely lethal once contracted; however, disease challenge experiments and varying spatial patterns of RRV spread suggest some level of immunity may exist. We first assessed patterns of local adaptation in raccoon populations along the eastern seaboard of North America by contrasting spatial patterns of neutral (microsatellite loci) and functional, major histocompatibility complex (MHC) genetic diversity and structure. We explored variation of MHC allele frequencies in the light of temporal population exposure to RRV (0–60 years) and specific RRV strains in infected raccoons. Our results revealed high levels of MHC variation (66 DRB exon 2 alleles) and pronounced genetic structure relative to neutral microsatellite loci, indicative of local adaptation. We found a positive association linking MHC genetic diversity and temporal RRV exposure, but no association with susceptibility and resistance to RRV strains. These results have implications for landscape epidemiology studies seeking to predict the spread of RRV and present an example of how population demographics influence the degree to which populations adapt to local selective pressures.     

外分泌型的乙型肝炎病毒核心抗原核酸疫苗的构建与体外表达

目的:构建含有组织型纤溶酶原激活剂(tPA)信号肽的乙型肝炎病毒核心抗原(HBcAg)核酸疫苗。方法将HBcAg基因用PCR方法扩增并分别引入相应的限制性内切酶酶切位点,然后克隆入pJW4303载体中获得相应的核酸疫苗,经筛选鉴定后,用上述核酸疫苗与野生型HBcAg核酸疫苗及空载体质粒pJW4303分别用脂质体瞬时转染293T细胞,应用蛋白印迹法检测核心抗原的表达。结果成功构建以pJW4303为载体的含tPA信号肽的HBcAg核酸疫苗,体外表达证实含tPA信号肽的HBcAg在293T细胞胞内和胞外均能表达,含tPA信号肽的HBcAg核酸疫苗的核心抗原表达水平较高。结论以pJW4303为载体的含tPA信号肽的HBcAg核酸疫苗能够将细胞内的HBcAg分泌到细胞外,为进一步研究其免疫原性打下了基础。     

Use of amphotericin B as optical probe to study conformational changes and thermodynamic stability in human serum albumin

The binding of polyene antibiotic amphotericin B to serum albumin was studied using absorption, fluorescence, and circular dichroism techniques. A hypochromic effect was observed in the absorption spectrum of amphotericin B in the presence of albumin with maxima at 366 nm, 385 nm, and 408 nm, which correspond to the absorption of the monomeric form of amphotericin B. A modification on the circular dichroism spectrum of amphotericin B in the presence of albumin was observed at bands 329 nm and 351 nm (excitronic interaction), which suggests that only amphotericin B monomer is bound to the protein. Amphotericin B perturbs the specific markers for sites I, II, and fatty acid binding site bound to these sites, suggesting that amphotericin B interacts with a great binding area in albumin. Lysines 199 and 525 in albumin participate in the molecular interaction between amphotericin B and the protein. The absorption spectrum of amphotericin B bound to albumin was sensitive to the chemical and thermal treatment of the protein, to neutral-basic transition of albumin and to conformational changes induced by the binding of other ligands to this protein.     

Use of mutual information arrays to predict coevolving sites in the full length HIV gp120 protein for subtypes B and C

It is well established that different sites within a protein evolve at different rates according to their role within the protein; identification of these correlated mutations can aid in tasks such as ab initio protein structure, structure function analysis or sequence alignment. Mutual Information is a standard measure for coevolution between two sites but its application is limited by signal to noise ratio. In this work we report a preliminary study to investigate whether larger sequence sets could circumvent this problem by calculating mutual information arrays for two sets of drug naïve sequences from the HIV gp120 protein for the B and C subtypes. Our results suggest that while the larger sequences sets can improve the signal to noise ratio, the gain is offset by the high mutation rate of the HIV virus which makes it more difficult to achieve consistent alignments. Nevertheless, we were able to predict a number of coevolving sites that were supported by previous experimental studies as well as a region close to the C terminal of the protein that was highly variable in the C subtype but highly conserved in the B subtype.     

Small proline-rich protein-1B is overexpressed in human oral squamous cell cancer stem-like cells and is related to their growth through activation of MAP kinase signal

Cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are considered to be essential for tumor maintenance, recurrence and metastasis. Therefore, eradication of CSCs/CICs is essential to cure cancers. However, the molecular mechanisms of CSCs/CICs are still elusive. In this study, we investigated the molecular mechanism of the cell growth of oral CSCs/CICs. Oral CSCs/CICs were isolated as aldehyde dehydrogenase 1 bright (ALDH1^br) cells by the ALDEFLUOR assay. Small proline-rich protein-1B (SPRR1B) gene was shown to be overexpressed in ALDH1^br cells by a cDNA microarray and RT-PCR. SPRR1B was shown to have a role in cell growth and maintenance of ALDH1^br cells by SPRR1B overexpression and knockdown experiments. To elucidate the molecular mechanism by which SPRR1B regulates cell growth, further cDNA microarray analysis was performed using SPRR1B-overexpressed cells and cells with SPRR1B knocked down by siRNA. Expression of the tumor suppressor gene Ras association domain family member 4 (RASSF4) was found to be suppressed in SPRR1B-overexpressed cells. On the other hand, the expression of RASSF4 was enhanced in cells in which SPRR1B expression was knocked down by SPRR1B-specific siRNA. RASSF4 has an RA (Ras association) domain, and we thus hypothesized that RASSF4 modulates the MAP kinase signal downstream of the Ras signal. MAP kinase signal was activated in SPRR1B-overexpressed cells, whereas the signal was suppressed in SPRR1B knocked down cells. Taken together, the results indicate that the expression of SPRR1B is upregulated in oral CSCs/CICs and that SPRR1B has a role in cell growth by suppression of RASSF4.