Is Rapoport's rule a recent phenomenon? A deep time perspective on potential causal mechanisms

Macroecology strives to identify ecological patterns on broad spatial and temporal scales. One such pattern, Rapoport''s rule, describes the tendency of species'' latitudinal ranges to increase with increasing latitude. Several mechanisms have been proposed to explain this rule. Some invoke climate, either through glaciation driving differential extinction of northern species or through increased seasonal variability at higher latitudes causing higher thermal tolerances and subsequently larger ranges. Alternatively, continental tapering or higher interspecific competition at lower latitudes may be responsible. Assessing the incidence of Rapoport''s rule through deep time can help to distinguish between competing explanations. Using fossil occurrence data from the Palaeobiology Database, we test these hypotheses by evaluating mammalian compliance with the rule throughout the Caenozoic of North America. Adherence to Rapoport''s rule primarily coincides with periods of intense cooling and increased seasonality, suggesting that extinctions caused by changing climate may have played an important role in erecting the latitudinal gradients in range sizes seen today.     

Raspberry ketone-supplemented diet has no effect on fitness parameters or lure responsiveness in male melon flies,Zeugodacus cucurbitae (Diptera: Tephritidae)

The male annihilation technique (MAT) and sterile insect technique (SIT) are often used to control pestiferous tephritid fruit flies (Diptera: Tephritidae). MAT involves the deployment of traps containing a male attractant and insecticide with the goal of drastically reducing male abundance and ultimately eliminating the entire population. SIT, which involves the mass production, sterilization, and release of the target species, may also be implemented to achieve final extirpation. Generally, simultaneous implementation of MAT and SIT is counterproductive, because the presence of large numbers of male-specific traps in the environment (MAT) would greatly reduce the number of sterile males available for copulating with wild females (SIT). However, studies on the Queensland fruit fly, Bactrocera tryoni (Froggatt), indicate that concurrent use of MAT and SIT may be feasible. Sexually mature males of B. tryoni are attracted to the raspberry ketone and its synthetic analogue cue-lure. Males of B. tryoni fed raspberry-ketone-supplemented diet when newly emerged showed lower attraction to cue-lure baited traps than control males. In addition, newly emerged males provided this diet displayed accelerated sexual maturation, which would allow the early release of sterile males and reduce pre-release holding costs. Here, we examined whether the addition of raspberry ketone to the adult diet of male melon flies, Zeugodacus cucurbitae (Coquillett), produced effects similar to those observed for B. tryoni. Despite using similar methods, no significant effect of raspberry ketone-supplemented diet on time to sexual maturity, survival, mating competitiveness, or attraction to cue-lure baited traps in mass-reared Z. cucurbitae males.     

RNA binding is more critical to the suppression of silencing function of Cucumber mosaic virus 2b protein than nuclear localization

Previously, we found that silencing suppression by the 2b protein and six mutants correlated both with their ability to bind to double-stranded (ds) small RNAs (sRNAs) in vitro and with their nuclear/nucleolar localization. To further discern the contribution to suppression activity of sRNA binding and of nuclear localization, we have characterized the kinetics of in vitro binding to a ds sRNA, a single-stranded (ss) sRNA, and a micro RNA (miRNA) of the native 2b protein and eight mutant variants. We have also added a nuclear export signal (NES) to the 2b protein and assessed how it affected subcellular distribution and suppressor activity. We found that in solution native protein bound ds siRNA, miRNA, and ss sRNA with high affinity, at protein:RNA molar ratios ~2:1. Of the four mutants that retained suppressor activity, three showed sRNA binding profiles similar to those of the native protein, whereas the remaining one bound ss sRNA at a 2:1 molar ratio, but both ds sRNAs with 1.5-2 times slightly lower affinity. Three of the four mutants lacking suppressor activity failed to bind to any sRNA, whereas the remaining one bound them at far higher ratios. NES-tagged 2b protein became cytoplasmic, but suppression activity in patch assays remained unaffected. These results support binding to sRNAs at molar ratios at or near 2:1 as critical to the suppressor activity of the 2b protein. They also show that cytoplasmically localized 2b protein retained suppressor activity, and that a sustained nuclear localization was not required for this function.     

Physicochemical sequence characteristics that influence S-palmitoylation propensity

Over the past 30 years, several hundred eukaryotic proteins spanning from yeast to man have been shown to be S-palmitoylated. This post-translational modification involves the reversible addition of a 16-carbon saturated fatty acyl chain onto the cysteine residue of a protein where it regulates protein membrane association and distribution, conformation, and stability. However, the large-scale proteome-wide discovery of new palmitoylated proteins has been hindered by the difficulty of identifying a palmitoylation consensus sequence. Using a bioinformatics approach, we show that the enrichment of hydrophobic and basic residues, the cellular context of the protein, and the structural features of the residues surrounding the palmitoylated cysteine all influence the likelihood of palmitoylation. We developed a new palmitoylation predictor that incorporates these identified features, and this predictor achieves a Matthews Correlation Coefficient of .74 using 10-fold cross validation, and significantly outperforms existing predictors on unbiased testing sets. This demonstrates that palmitoylation sites can be predicted with accuracy by taking into account not only physiochemical properties of the modified cysteine and its surrounding residues, but also structural parameters and the subcellular localization of the modified cysteine. This will allow for improved predictions of palmitoylated residues in uncharacterized proteins. A web-based version of this predictor is currently under development.     

The effect of osteoporosis on residual ridge resorption and masticatory performance in denture wearers

doi: 10.1111/j.1741‐2358.2011.00610.x The effect of osteoporosis on residual ridge resorption and masticatory performance in denture wearers Aim: To compare masticatory performance, masticatory efficiency and residual ridge resorption (RRR) in osteoporotic and non‐osteoporotic edentulous subjects after rehabilitation with complete dentures. Method: Thirty subjects fulfilling the inclusion criteria were enrolled from the patients visiting the Department of Prosthodontics for complete denture fabrication. Two groups consisting of control subjects (group I; N = 15) and osteoporotic subjects (group II; N = 15) were formed. Complete dentures satisfying certain criteria were fabricated for both groups. Masticatory performance and efficiency were measured 6 months after denture insertion. Areal measurements were taken on lateral cephalograms before and 6 months after denture fabrication. The data were then computed to analyse differences between groups I and II using SPSS statistical software version 15.0. Results: Six months after denture fabrication, the masticatory performance and efficiency were significantly higher (p < 0.001) for group I, with a significant decrease in maxillary and mandibular sagittal area seen in both groups. The rate of bone loss was more in group II compared with group I. Conclusion: Greater masticatory function was demonstrated by the non‐osteoporotic group, and the rate of RRR was more in the osteoporotic group compared with the normal group. In this pilot study, osteoporosis leads to greater RRR, decreased masticatory performance and efficiency in edentulous subjects 6 months after denture insertion. Screening for osteoporosis is suggested as a routine procedure for all edentulous subjects undergoing rehabilitation. Recall check‐ups for osteoporotic patients should be more frequent, and these patients may require more frequent denture remakes.     

Microbial populations stimulated for hexavalent uranium reduction in uranium mine sediment

Uranium-contaminated sediment and water collected from an inactive uranium mine were incubated anaerobically with organic substrates. Stimulated microbial populations removed U almost entirely from solution within 1 month. X-ray absorption near-edge structure analysis showed that U(VI) was reduced to U(IV) during the incubation. Observations by transmission electron microscopy, selected area diffraction pattern analysis, and energy-dispersive X-ray spectroscopic analysis showed two distinct types of prokaryotic cells that precipitated only a U(IV) mineral uraninite (UO(2)) or both uraninite and metal sulfides. Prokaryotic cells associated with uraninite and metal sulfides were inferred to be sulfate-reducing bacteria. Phylogenetic analysis of 16S ribosomal DNA obtained from the original and incubated sediments revealed that microbial populations were changed from microaerophilic Proteobacteria to anaerobic low-G+C gram-positive sporeforming bacteria by the incubation. Forty-two out of 94 clones from the incubated sediment were related to sulfate-reducing Desulfosporosinus spp., and 23 were related to fermentative Clostridium spp. The results suggest that, if in situ bioremediation were attempted in the uranium mine ponds, Desulfosporosinus spp. would be a major contributor to U(VI) and sulfate reduction and Clostridium spp. to U(VI) reduction.     

Improving male mating competitiveness and survival in the field for medfly,Ceratitis capitata (Diptera: Tephritidae) SIT programs

The success of the sterile insect technique (SIT) depends critically upon mating between released sterilized males and wild females. In Hawaii, improvements in the efficiency of sterile males were attempted on two separate fronts – mating enhancement and survival improvement. In the former, two methods have been investigated – selective breeding and aromatherapy. In the latter, flies which survived in field cages for several days were selected and bred to produce progeny with enhanced survival ability compared to control flies. Regarding mating selection, standard laboratory-reared males that successfully mated with wild females in field cages were allowed to breed. F1 offspring were inbred, then the selection procedure was repeated for four additional cycles. In the aromatherapy procedure, laboratory-reared males were exposed to ginger root oil for several hours 1 day prior to testing in field cages. Compared to controls, the selected flies improved the mating competitiveness of male flies ca. 3-fold, irradiation reduced this increase to ca. 2.5-fold. Exposing the selected, hybrid strain raised the fitness of the lab males to ca. 9-fold that of wild males. In the ongoing survival selection study, we have obtained lines in which the selected males survived ca. 2-fold better than laboratory control males over several days in an outdoor field cage, with food and water provided. The goal is to combine the traits of higher survival and mating ability into a single strain for SIT release.     

Infection of tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus with betasatellites, results in enhanced level of helper virus components and antagonistic interaction between DNA B and betasatellites

Tomato leaf curl New Delhi virus (ToLCNDV) (Geminiviridae) is an important pathogen that severely affects tomato production. An extensive survey was carried out during 2003–2010 to study the diversity of begomoviruses found in tomato, potato, and cucurbits that showed symptoms of leaf puckering, distortion, curling, vein clearing, and yellow mosaic in various fields in different regions of India. Ten begomovirus isolates were cloned from infected samples and identified as belonging to the species ToLCNDV. A total of 44 % of the samples showed association of betasatellites, with CLCuMuB and LuLDB being the most frequent. The ToLCNDV cloned component DNA A and DNA B were agroinoculated on Nicotiana benthamiana and tomato (Solanum lycopersicum) plants with or without betasatellites, CLCuMuB or LuLDB. The viral genome levels were then monitored by real-time polymerase chain reaction at different time points of disease development. Plants co-inoculated with betasatellites showed enhanced symptom severity in both N. benthamiana and tomato, as well as increases in helper viral DNA A and DNA B levels. The DNA B and betasatellites acted antagonistically to each other, so that the level of DNA B was 16-fold greater in the presence of betasatellites, while accumulation of betasatellites, CLCuMuB and LuLDB, were reduced by 60 % in the presence of DNA B. DNA B-mediated symptoms predominated in CLCuMuB-inoculated plants, whereas betasatellite-mediated leaf abnormalities were prominent in LuLDB-co-inoculated plants. Inoculation with the cloned components will be a good biotechnological tool in resistance breeding program.     

Extension of the single amino acid chelate concept (SAAC) to bifunctional biotin analogues for complexation of the M(CO)3(+1) Core (M = Tc and Re): syntheses, characterization, biotinidase stability, and avidin binding

Biotin and avidin form one of the most stable complexes known (K(D) = 10(-15) M(-1)) making this pairing attractive for a variety of biomedical applications including targeted radiotherapy. In this application, one of the pair is attached to a targeting molecule, while the other is subsequently used to deliver a radionuclide for imaging and/or therapeutic applications. Recently, we reported a new single amino acid chelate (SAAC) capable of forming stable complexes with Tc(CO)3 or Re(CO)3 cores. We describe here the application of SAAC analogues for the development of a series of novel radiolabeled biotin derivatives capable of forming robust complexes with both Tc and Re. Compounds were prepared through varying modification of the free carboxylic acid group of biotin. Each 99mTc complex of SAAC-biotin was studied for their ability to bind avidin, susceptibility to biotinidase, and specificity for avidin in an in vivo avidin-containing tumor model. The radiochemical stability of the 99mTc(CO)3 complexes was also investigated by challenging each 99mTc-complex with large molar excesses of cysteine and histidine at elevated temperature. All compounds were radiochemically stable for greater than 24 h at elevated temperature in the presence of histidine and cysteine. Both [99mTc(CO)3(L6)]+1 [TcL6; L6 = biotinylamidopropyl-N,N-(dipicolyl)amine] and [99mTc(CO)3(L12a)]+1 (TcL12; L12 = N,N-(dipicolyl)biotinamido-Boc-lysine; TcL12a; L12a = N,N-(dipicolyl)biotinamide-lysine) readily bound to avidin whereas [99mTc(CO)3(L9)]+1 [TcL9; L9 = N,N-(dipicolyl)biotinamine] demonstrated minimal specific binding. TcL6 and TcL9 were resistant to biotinidase cleavage, while TcL12a, which contains a lysine linkage, was rapidly cleaved. The highest uptake in an in vivo avidin tumor model was exhibited by TcL6, followed by TcL9 and TcL12a, respectively. This is likely the result of both intact binding to avidin and resistance to circulating biotinidase. Ligand L6 is the first SAAC analogue of biotin to demonstrate potential as a radiolabeled targeting vector of biotin capable of forming robust radiochemical complexes with both 99mTc and rhenium radionuclides. Computational simulations were performed to assess biotin-derivative accommodation within the binding site of the avidin. These calculations predict that deformation of the surface domain of the binding pocket can occur to accommodate the transition metal-biotin derivatives with negligible changes to the inner-beta-barrel, the region most responsible for binding and retaining biotin and its derivatives. The biological activity and biodistribution of the technetium complexes TcL6, TcL9, and TcL12a were examined in an avidin tumor model. In the avidin bead tumor localization model, TcL6 demonstrated the most favorable localization with a 7:1 ratio of avidin bead implanted muscle versus normal muscle, while TcL9 exhibited a 2:1 ratio. However, TcL9 displayed no specificity for avidin.