Behavioural thermoregulation and climatic range restriction in the globally threatened Ethiopian Bush‐crow Zavattariornis stresemanni

Climate may influence the distribution and abundance of a species through a number of demographic and ecological processes, but the proximate drivers of such responses are only recently being identified. The Ethiopian Bush‐crow Zavattariornis stresemanni is a starling‐like corvid that is restricted to a small region of southern Ethiopia. It is classified as Endangered in the IUCN Red List of globally threatened species. Previous work suggested that this range restriction is almost perfectly defined by a climate envelope that is cooler than surrounding areas, but the proximate mechanism remains unexplained. The heavily altered habitats which the species inhabits are widespread across Africa, and recent work has shown that the Bush‐crow is behaviourally adaptable and has a catholic diet. We assess whether its enigmatic distribution can be explained by behavioural responses to the higher temperatures that surround its current range. Using environmental niche models and field observations of thermally mediated behaviour, we compare the range restriction and behavioural thermoregulation of the Ethiopian Bush‐crow with those of two sympatric control species that are similar in size and ecology, but have much larger ranges that include hotter environments. White‐crowned Starling Lamprotornis albicapillus and Superb Starling L. superbus occupy similar habitats to the Ethiopian Bush‐crow and all three frequently forage together. We found that the Bush‐crow's range is limited primarily by temperature, with a secondary effect of dry season rainfall, whereas the ranges of the two starling species are better predicted by wet season rainfall alone. Bush‐crows exhibited panting behaviour and moved into the shade of trees at significantly lower ambient temperatures than did the starlings, and their food intake declined more steeply with increasing temperature. These results indicate that the limited geographical range of the Bush‐crow reflects an inability to cope with higher temperatures. This suggests that a species' response to climate change might not be easily predicted by its ecological generalism, and may represent an inherited debt from its evolutionary history.     

The responses of Apis mellifera jemenitica to different artificial queen rearing techniques

In the current study, we investigated if any variations exist in acceptance rate of grafted larvae and quality of queens reared in different queen cell cup sizes, between wet and dry grafting and between queen right and queen less conditions of A. m. jemenitica colonies. The acceptance rate of grafted larvae in different queen cell cup sizes (7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm) were varying from 69 to 71% and the variations were not significant among the different queen cups sizes but averagely lower than the acceptances recorded for other races. Out of the 172 dry grafted larvae, only 56.4% of them were accepted while in wet grafting out of 174 grafted larvae 77.01% were accepted. Regarding the rate of sealing, 48.84% and 71.84% of them sealed for dry and wet grafts, respectively. The observed variation in the rate of acceptance and sealing were significant (N = 346, df = 1, P < 0.0001) between the two techniques. However, there was no significant difference in fresh weight of emerged queens between the two grafting methods. Out of the 324 grafted larvae given to queen right and queen less starter colonies each; 106 (32.72%) and 252 (73.68%) were accepted in queen right and queen less starter colonies, respectively and the variation was highly significant at P < 0.0001. The total number of sealed pupae were 82 (25.31%) and 216 (63.16%) for queen right and queen less colonies, respectively and the variations was significant at P < 0.0001. From the study it can be concluded that A. m. jemenitica colonies can rear significantly more queens under wet grafting and in queen less colonies conditions than dry grafting and queen right conditions     

Reproductive biology and morphology of Apis mellifera jemenitica (Apidae) queens and drones

The current study aimed to investigate the important reproductive biology and morphology of A.m. jemenitica queens and drones through measuring the weight of virgin and mated queens, size and weight of spermathecae, weight of ovaries, number of ovarioles, quantity and viability of semen in queen and drones. Accordingly, the average weights of 0.139 ± 0.01 g and 0.143 ± 0.013 g recorded for virgin and mated queens respectively. The sizes of spermathecae were 1.248 ± 0.103 mm and 1.25 ± 0.022 mm for virgin and mated queens respectively. The mean weight of ovaries was 0.013 ± 0.003 g and the numbers of ovarioles varied from 124 to 163 with the mean of 142.9 ± 9.47 and with no significant difference between virgin and mated queens. The average number of stored sperm per spermathecae of mated queen was estimated to be 4.202 ± 0.613 million with the viability of 80.39%. The average number of sperm per drone recorded was 8,763,950 ± 1,633,203.15 with viability of 79.54 ± 6.70%. In general, the current study revealed that the values recorded for reproductive biology and morphological characters of A. m. jemenitica queens and drones were relatively lower than values recorded for other Apis mellifera races. This mainly could be associated with the body size of the race which is known to be the smallest race among A. mellifera races. Moreover, the harsh environmental conditions of the regions, high temperature, low humidity and limited resources may have contributed for the smaller biological and morphological values. The information will serve as a base in future selection and breeding of program of the race.     

Characterization of SIV-specific CD4+ T-helper proliferative responses in macaques immunized with live-attenuated SIV

Analysis of immune responses generated by live-attenuated simian immunodeficiency virus (SIV) strains may provide clues to the mechanisms of protective immunity induced by this approach. We examined SIV-specific T-helper responses in macaques immunized with the live-attenuated SIV strains SIVmac239deltanef and SIVmac239delta3. Optimization of the concentration and duration of antigenic stimulation resulted in the detection of relatively strong SIV-specific proliferative responses, with peak stimulation indices of up to 84. SIV-specific proliferative responses were mediated by CD4+ T cells and were major histocompatibility (MHC) class II restricted. Limiting dilution analysis revealed SIV-specific T-helper precursor frequencies of up to 96 per 10(6) peripheral blood mononuclear cells (PBMC). Intracellular flow-cytometric analysis demonstrated the production of interleukin (IL)-2, interferon (IFN)-gamma, RANTES and macrophage inhibitory protein-1alpha (MIP-1alpha) by T lymphocytes from SIVmac239deltanef-vaccinated animals following SIV p55 stimulation. Induction of strong SIV-specific T-helper responses by live-attenuated SIV vaccines may play a role in their ability to induce protective immunity.     

Propagation of recombinant vaccinia virus in HeLa cells: adsorption kinetics and replication in batch cultures.

The influence of various culture parameters on infection and replication of recombinant vaccinia virus in HeLa cells was examined during various phases of viral replication. A modified form of the model of Valentine and Allison (Biochim. Biophys. Acta 1960, 40, 393-399) model was used to predict successfully the viral adsorption rates in cell suspensions. An experimentally determined aggregation factor, epsilon, was included in the model to account for deviations of the observed adsorption rates from those predicted by the earlier model. It was also shown that the ionic strength, ionic species, and serum proteins present in the medium significantly altered the adsorption kinetics of the virus. The lysosomotropic base chloroquine was found to enhance viral infection more than 2-fold during the penetration step of viral infection. It was also demonstrated that cells infected during the exponential growth phase gave higher viral yields than those infected during the lag or stationary growth phases and the initial viral MOI did not significantly alter viral yields. Finally, it was demonstrated that viral infection of HeLa cells grown in 4-L bioreactor batch cultures resulted in increased death and glucose uptake rates and significantly lower growth rates.     

Amphotericin B channels in phospholipid membrane-coated nanoporous silicon surfaces: implications for photovoltaic driving of ions across membranes

The antimycotic agent amphotericin B (AmB) functions by forming complexes with sterols to form ion channels that cause membrane leakage. When AmB and cholesterol mixed at 2:1 ratio were incorporated into phospholipid bilayer membranes formed on the tip of patch pipettes, ion channel current fluctuations with characteristic open and closed states were observed. These channels were also functional in phospholipid membranes formed on nanoporous silicon surfaces. Electrophysiological studies of AmB-cholesterol mixtures that were incorporated into phospholipid membranes formed on the surface of nanoporous (6.5 nm pore diameter) silicon plates revealed large conductance ion channels ( approximately 300 pS) with distinct open and closed states. Currents through the AmB-cholesterol channels on nanoporous silicon surfaces can be driven by voltage applied via conventional electrical circuits or by photovoltaic electrical potential entirely generated when the nanoporous silicon surface is illuminated with a narrow laser beam. Electrical recordings made during laser illumination of AmB-cholesterol containing membrane-coated nanoporous silicon surfaces revealed very large conductance ion channels with distinct open and closed states. Our findings indicate that nanoporous silicon surfaces can serve as mediums for ion-channel-based biosensors. The photovoltaic properties of nanoporous silicon surfaces show great promise for making such biosensors addressable via optical technologies.     

Improved bio-energy yields via sequential ethanol fermentation and biogas digestion of steam exploded oat straw

Using standard laboratory equipment, thermochemically pretreated oat straw was enzymatically saccharified and fermented to ethanol, and after removal of ethanol the remaining material was subjected to biogas digestion. A detailed mass balance calculation shows that, for steam explosion pretreatment, this combined ethanol fermentation and biogas digestion converts 85-87% of the higher heating value (HHV) of holocellulose (cellulose and hemicellulose) in the oat straw into biofuel energy. The energy (HHV) yield of the produced ethanol and methane was 9.5-9.8 MJ/(kg dry oat straw), which is 28-34% higher than direct biogas digestion that yielded 7.3-7.4 MJ/(kg dry oat straw). The rate of biogas formation from the fermentation residues was also higher than from the corresponding pretreated but unfermented oat straw, indicating that the biogas digestion could be terminated after only 24 days. This suggests that the ethanol process acts as an additional pretreatment for the biogas process.     

Construction and characterization of replication-competent simian immunodeficiency virus vectors that express gamma interferon.

We report the construction and characterization of several replication-competent simian immunodeficiency virus (SIV) vectors with a deletion in the viral nef gene (SIV(delta nef)) that express gamma interferon (IFN-gamma). The expression of the cytokine gene was controlled either by the simian virus 40 early promoter or by the SIV 5' long terminal repeat regulatory sequences, utilizing the nef gene splice signals. To enhance the expression of IFN-gamma, the two in-frame nef start codons were mutated without altering the Env amino acid sequence (SIV(HyIFN)). Plasmids containing full-length proviral genomes were used to obtain high-titer stocks of each recombinant virus in cell cultures. Expression of IFN-gamma by SIV(HyIFN) reached levels as high as 10(6) U/ml after 11 days in culture. The IFN-gamma gene was unstable and sustained deletions after serial passage of SIV(delta nef) vectors in CEM-X-174 cells. The degree of instability appears to depend on size and orientation of the insert and the expression of IFN-gamma. Only one virus, SIV(HyIFN), expressed detectable levels of IFN-gamma up to the sixth passage. Prospects for the use of IFN-gamma and other lymphokines to enhance the safety and efficacy of live attenuated vaccines are discussed.     

Induction of potent humoral and cell-mediated immune responses by attenuated vaccinia virus vectors with deleted serpin genes

Vaccinia virus (VV) has been effectively utilized as a live vaccine against smallpox as well as a vector for vaccine development and immunotherapy. Increasingly there is a need for a new generation of highly attenuated and efficacious VV vaccines, especially in light of the AIDS pandemic and the threat of global bioterrorism. We therefore developed recombinant VV (rVV) vaccines that are significantly attenuated and yet elicit potent humoral and cell-mediated immune responses. B13R (SPI-2) and B22R (SPI-1) are two VV immunomodulating genes with sequence homology to serine protease inhibitors (serpins) that possess antiapoptotic and anti-inflammatory properties. We constructed and characterized rVVs that have the B13R or B22R gene insertionally inactivated (vDeltaB13R and vDeltaB22R) and coexpress the vesicular stomatitis virus glycoprotein (v50DeltaB13R and v50DeltaB22R). Virulence studies with immunocompromised BALB/cBy nude mice indicated that B13R or B22R gene deletion decreases viral replication and significantly extends time of survival. Viral pathogenesis studies in immunocompetent CB6F(1) mice further demonstrated that B13R or B22R gene inactivation diminishes VV virulence, as measured by decreased levels of weight loss and limited viral spread. Finally, rVVs with B13R and B22R deleted elicited potent humoral, T-helper, and cytotoxic T-cell immune responses, revealing that the observed attenuation did not reduce immunogenicity. Therefore, inactivation of immunomodulating genes such as B13R or B22R represents a general method for enhancing the safety of rVV vaccines while maintaining a high level of immunogenicity. Such rVVs could serve as effective vectors for vaccine development and immunotherapy.     

Mapping Potential Amplification and Transmission Hotspots for MERS-CoV,Kenya

Dromedary camels have been implicated consistently as the source of Middle East respiratory syndrome coronavirus (MERS-CoV) human infections and attention to prevent and control it has focused on camels. To understanding the epidemiological role of camels in the transmission of MERS-CoV, we utilized an iterative empirical process in Geographic Information System (GIS) to identify and qualify potential hotspots for maintenance and circulation of MERS-CoV, and produced risk-based surveillance sites in Kenya. Data on camel population and distribution were used to develop camel density map, while camel farming system was defined using multi-factorial criteria including the agro-ecological zones (AEZs), production and marketing practices. Primary and secondary MERS-CoV seroprevalence data from specific sites were analyzed, and location-based prevalence matching with camel densities was conducted. High-risk convergence points (migration zones, trade routes, camel markets, slaughter slabs) were profiled and frequent cross-border camel movement mapped. Results showed that high camel-dense areas and interaction (markets and migration zones) were potential hotspot for transmission and spread. Cross-border contacts occurred with in-migrated herds at hotspot locations. AEZ differential did not influence risk distribution and plausible risk factors for spatial MERS-CoV hotspots were camel densities, previous cases of MERS-CoV, high seroprevalence and points of camel convergences. Although Kenyan camels are predisposed to MERS-CoV, no shedding is documented to date. These potential hotspots, determined using anthropogenic, system and trade characterizations should guide selection of sampling/surveillance sites, high-risk locations, critical areas for interventions and policy development in Kenya, as well as instigate further virological examination of camels.