Assessing the use of genomic DNA as a predictor of the maximum absorbance wavelength of avian SWS1 opsin visual pigments

Recently, in vitro mutation studies have made it possible to predict the wavelengths of maximum absorbance (λ_max) of avian UV/violet sensitive visual pigments (SWS1) from the identity of a few key amino acid residues in the opsin gene. Given that the absorbance spectrum of a cone’s visual pigment and of its pigmented oil droplet can be predicted from just the λ_max, it may become possible to predict the entire spectral sensitivity of a bird using genetic samples from live birds or museum specimens. However, whilst this concept is attractive, it must be validated to assess the reliability of the predictions of λ_max from opsin amino acid sequences. In this paper, we have obtained partial sequences covering three of the known spectral tuning sites in the SWS1 opsin and predicted λ_max of all bird species for which the spectral absorbance has been measured using microspectrophotometry. Our results validate the use of molecular data from genomic DNA to predict the gross differences in λ_max between the violet- and ultraviolet-sensitive subtypes of SWS1 opsin. Additionally, we demonstrate that a bird, the bobolink Dolichonyx oryzivorus L., can have more than one SWS1 visual pigment in its retina.     

Acaricidal effects of <Emphasis Type="Italic">Corymbia citriodora</Emphasis> oil containing <Emphasis Type="Italic">para</Emphasis>-menthane-3,8-diol against nymphs of <Emphasis Type="Italic">Ixodes ricinus</Emphasis> (Acari: Ixodidae)

The toxicity of para-menthane-3,8-diol (PMD), the main arthropod-repellent compound in the oil of the lemon eucalyptus, Corymbia citriodora, was evaluated against nymphs of Ixodes ricinus using five methods (A–E) of a contact toxicity bioassay. Mortality rates were estimated by recording numbers of dead nymphs at 30 min intervals during the first 5 h after the start of exposure and at longer intervals thereafter. The mortality rate increased with increasing concentration of PMD and duration of exposure with a distinct effect after 3.5 h. From the results obtained by methods A, C and E, the LC₅₀ range was 0.035–0.037 mg PMD/cm² and the LC₉₅ range was 0.095–0.097 mg PMD/cm² at 4 h of exposure; the LT₅₀ range was 2.1–2.8 h and the LT₉₅ range was 3.9–4.2 h at 0.1 mg PMD/cm². To determine the duration of toxic activity of PMD, different concentrations (0.002, 0.01, 0.1 mg PMD/cm²) were tested and mortality was recorded at each concentration after 1 h; thereafter new ticks were tested. This test revealed that the lethal activity of PMD remained for 24 h but appeared absent after 48 h. The overall results show that PMD is toxic to nymphs of I. ricinus and may be useful for tick control.     

Understory plant diversity is related to higher variability of vegetative mobility of coexisting species

Theoretical studies claim that if co-occurring species have very different mobilities this will result in greater small-scale species richness, but empirical evidence is still lacking. We measured horizontal vegetative mobility (VM) of 48 herbaceous understory species and estimated small-scale species richness in early and late successional boreonemoral herb-rich coniferous forests in central Estonia. VM of erosulate growth forms was significantly higher than that of hemi-rosette and rosette growth forms. Erosulate species exhibited higher mobility in young stands, but their relative and total cover was considerably higher in old stands. Local plant richness (in 1 × 1 m plots) correlated positively with the variability of VM of species in a plot—larger differences in VM resulted in a higher number of coexisting species. Our results thus suggest that species differences in VM can contribute to small-scale coexistence by providing different ways to colonise empty space. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The role of <Emphasis Type="Italic">stj</Emphasis> fimbrial operon in the intestinal persistence of <Emphasis Type="Italic">Salmonella</Emphasis> Typhimurium in mice

Salmonella Typhimurium contains 13 operons coding for fimbriae with unique binding specificities to host epithelial surfaces. stj operon is only detected in S. Typhimurium genome suggesting that Stj fimbria may effect serovarspecific virulence characteristics. In this study, the role of stj fimbrial operon in the long-term persistence of S. Typhimurium was identified by competitive infection experiment in genetically resistant mouse (CBA) model system. Knock-out mutation of stjA (major subunit of the Stj fimbria) gene reduced recovery of S. Typhimurium from fecal samples and its colonization to spleen, cecum and mesenteric lymph nodes over a 34-day time period (p < 0.05). This data indicate that stj fimbrial operon has a role in long-term intestinal persistence of S. Typhimurium in CBA mice.     

Seed macro and micro morphology of the selected <Emphasis Type="Italic">Nigella</Emphasis> (Ranunculaceae) taxa from Turkey and their systematic significance

Macro and micromorphological properties of intact and mature seeds of 12 taxa (species and varieties) belonging to Nigella L. (Ranunculaceae) was investigated using light and scanning electron microscopy. Material studied covers 11 species of 15 Turkish Nigella. Studied taxa were divided into two types. Type I has ovate to orbicular seeds that includes four species. Type II has triquedrous seeds and includes seven species. Type II was subdivided into two. Type IIa has triquedrous to subpyramidal seeds (five species) and Type IIb has triquedrous to subglobose seeds (two species). Further segregation was performed micromorphologically and an identification key of studied Nigella taxa was given. Studied Nigella taxa have a diverse macro and micromorphological characters that utilize to separate them from each other to assess the systematics of Nigella.     

Regulation of apoptosis-associated lysosomal membrane permeabilization

Lysosomal membrane permeabilization (LMP) occurs in response to a large variety of cell death stimuli causing release of cathepsins from the lysosomal lumen into the cytosol where they participate in apoptosis signaling. In some settings, apoptosis induction is dependent on an early release of cathepsins, while under other circumstances LMP occurs late in the cell death process and contributes to amplification of the death signal. The mechanism underlying LMP is still incompletely understood; however, a growing body of evidence suggests that LMP may be governed by several distinct mechanisms that are likely engaged in a death stimulus- and cell-type-dependent fashion. In this review, factors contributing to permeabilization of the lysosomal membrane including reactive oxygen species, lysosomal membrane lipid composition, proteases, p53, and Bcl-2 family proteins, are described. Potential mechanisms to safeguard lysosomal integrity and confer resistance to lysosome-dependent cell death are also discussed.     

Inhibition of Glomerular Mesangial Cell Proliferation by siPDGF-B- and siPDGFR-β-Containing Chitosan Nanoplexes

Mesangioproliferative glomerulonephritis is a disease that has a high incidence in humans. In this disease, the proliferation of glomerular mesangial cells and the production of extracellular matrix are important. In recent years, the RNAi technology has been widely used in the treatment of various diseases due to its capability to inhibit the gene expression with high specificity and targeting. The objective of this study was to decrease mesangial cell proliferation by knocking down PDGF-B and its receptor, PDGFR-β. To be able to use small interfering RNAs (siRNAs) in the treatment of this disease successfully, it is necessary to develop appropriate delivery systems. Chitosan, which is a biopolymer, is used as a siRNA delivery system in kidney drug targeting. In order to deliver siRNA molecules targeted at PDGF-B and PDGFR-β, chitosan/siRNA nanoplexes were prepared. The in vitro characterization, transfection studies, and knockdown efficiencies were studied in immortalized and primary rat mesangial cells. In addition, the effects of chitosan nanoplexes on mesangial cell proliferation and migration were investigated. After in vitro transfection, the PDGF-B and PDGFR-β gene silencing efficiencies of PDGF-B and PDGFR-β targeting siRNA-containing chitosan nanoplexes were 74 and 71% in immortalized rat mesangial cells and 66 and 62% in primary rat mesangial cells, respectively. siPDGF-B- and siPDGFR-β-containing nanoplexes indicated a significant decrease in mesangial cell migration and proliferation. These results suggested that mesangial cell proliferation may be inhibited by silencing of the PDGF-B signaling pathway. Gene silencing approaches with chitosan-based gene delivery systems have promise for the efficient treatment of renal disease.     

Hypolimnetic phosphorus and nitrogen dynamics in a small,eutrophic lake with a seasonally anoxic hypolimnion

In situ estimates of sediment nutrient flux are necessary to understand seasonal variations in internal loading in lakes. We investigated the sources and sinks of nutrients in the hypolimnion of a small (0.33 km²), relatively shallow (18 m max. depth), eutrophic lake (Lake Okaro, New Zealand) in order to determine changes in sediment nutrient fluxes resulting from a whole lake sediment capping trial using a modified zeolite phosphorus inactivation agent (Z2G1). Sediment nutrient fluxes in the hypolimnion were estimated as the residual term in a nutrient budget model that accounted for mineralisation of organic nutrients, nutrient uptake by phytoplankton and mixing, nitrification, adsorption/desorption and diffusion of dissolved nutrients at the thermocline. Of the total hypolimnetic phosphate and ammonium fluxes during one period of seasonal stratification (2007–08), up to 60 and 50%, respectively, were derived from the bottom sediments, 18 and 24% were due to mineralisation of organic species, 36 and 28% were due to phytoplankton uptake and 9 and 6% were from diffusion across the thermocline. Adsorption/desorption of phosphate to suspended solids and nitrification were of minor (<8%) importance to the total fluxes. Any reduction in sediment nutrient release by Z2G1 was small compared with both the total sediment nutrient flux and the sum of other hypolimnetic fluxes. Uneven sediment coverage of Z2G1 may have been responsible for the limited effect of the sediment capping layer formed by Z2G1.     

Sleep stage and obstructive apneaic epoch classification using single-lead ECG

Background  

Polysomnography (PSG) is used to define physiological sleep and different physiological sleep stages, to assess sleep quality and diagnose many types of sleep disorders such as obstructive sleep apnea. However, PSG requires not only the connection of various sensors and electrodes to the subject but also spending the night in a bed that is different from the subject's own bed. This study is designed to investigate the feasibility of automatic classification of sleep stages and obstructive apneaic epochs using only the features derived from a single-lead electrocardiography (ECG) signal.