Occupancy patterns of the introduced,predatory sugar glider in Tasmanian forests

Introduced mammals pose serious threats to native island fauna, and understanding their distribution is fundamental to evaluating their conservation impact. Introduced sugar gliders (Petaurus breviceps) are the main predator of critically endangered swift parrots (Lathamus discolor) on mainland Tasmania. We surveyed sugar glider occurrence over ~800 km² in an important swift parrot breeding area, the Southern Forests. During 4–5 visits per site, we used call broadcast of predatory owls to elicit sugar glider alarm calls and surveyed 100 sites during February/March 2016. Naïve occupancy by sugar gliders was high (0.79), as was detectability (0.52 ± 0.03 SE), resulting in a cumulative detection probability of effectively 1. Occupancy modelling indicated a positive effect of the proportion of mature forest cover on occupancy. The best model, based on AIC scores, included the proportion of mature forest cover within a 500 m radius with constant detectability. Our study revealed surprisingly high rates of occupancy of available forest habitat throughout the heavily logged study area, such that even when mature forest cover was <10%, sugar glider occupancy was >0.5; where forest cover approached 100% (i.e. in the best quality breeding habitat for swift parrots), occupancy by sugar gliders approached 1. Our results reveal that sugar gliders are widespread across the study area which may be indicative of occupancy rates elsewhere in the breeding range of the critically endangered swift parrot. As a result, the risk of predation by sugar gliders for small birds may be widespread across logged Tasmanian forests. Additional work to identify whether population densities of sugar gliders vary with forest cover (and whether this may impact predation likelihood) is critical to understanding the conservation consequences of deforestation in the breeding range of the swift parrot.     

The Phenolics of the Ornithogalum umbellatum L. (Hyacinthaceae): Phytochemical and Ecological Characterization

Ornithogalum umbellatum L. is a widely distributed species in Europe, that exhibits considerable variability at ecological, morphological, anatomical, and karyological level. Previous reports of the chemical investigations among Ornithogalum species indicate significant diversity of the secondary metabolites, as well. Knowing that environment affects the phenolic composition in plants to a large extent, the main objective of the research was to define relationship between phytochemical and ecological characters. To estimate an environmental influence on these results, plant material was collected at four habitats that differ in ecological factors and belong to two biogeographical regions: the Balkan Peninsula and the Pannonian Plane. Measured phytochemical characters are yield of dry extract, total phenolic and flavonoid contents, the presence of selected phenolic compounds as well as free‐radical scavenging activity (neutralization of DPPH and OH radicals). Results revealed that all analyzed phytochemical parameters differ between investigated O. umbellatum samples. The moisture level of habitat has the highest correlation, either positive or negative, with most of phytochemical characters, and is followed by temperature and soil reaction. Light intensity and nitrogen level have mostly moderate correlation coefficient with phytochemical characters. More complex correlation is revealed between ecological factors and nine phenolic compounds, with three observed patterns of relationship.     

Interaction of extravillous trophoblast galectin-1 and mucin(s)—Is there a functional relevance?

ABSTRACT

In the course of embryo implantation extensive interaction of the trophoblast with uterine tissue is crucial for adequate trophoblast invasion. This interaction is highly controlled, and it has been pointed out that a specific glycocode and changes in glycosylation may be important for successful implantation and maintenance of pregnancy. Both uterine and trophoblast cells have been shown to express cell surface glycoconjugates and sugar binding proteins, such as mucins (MUC) and galectins (gals). An increasing number of studies have investigated potential candidates interacting in this process. However, knowledge about the biochemical nature of the interactions and their importance for trophoblast cell function, and, consequently, for pregnancy outcome are still lacking. This review is aimed at deliberating the possibility that mucins, as heavily glycosylated proteins, might be among the functionally relevant galectin ligands in human trophoblast, based on both published data and our original research.     

Adjustment of incubation according to the threat posed: a further signal of enemy recognition in the Blackcap Sylvia atricapilla?

Nest predation and brood parasitism are costly for nest owners, and natural selection should therefore favour the evolution of parental counterdefences. We addressed the question of whether Blackcaps Sylvia atricapilla change their incubation behaviour in response to various nest intruders and whether this adjustment matches the intensity of mobbing exhibited towards these intruders. Near focal nests, we successively exposed a dummy of a brood parasite, nest predator and an innocuous species. After the parents had responded, we removed the dummy and filmed their incubation. The most aggressive response towards the Common Cuckoo Cuculus canorus and high nest attendance after its disappearance indicated recognition of the brood parasite. Low-intensity response to the Jay Garrulus glandarius, together with reduced subsequent parental care, suggested that Blackcaps perceived it either as less deleterious at the egg stage than the Cuckoo or as a danger to themselves. Almost no aggression towards the Turtle Dove Streptopelia turtur, along with the resumption of incubation after its removal, implied that Blackcaps recognised it as harmless. In addition, we found that the level of aggression positively correlated with nest attendance, suggesting a link between the intensity of mobbing and subsequent parental care. Altogether, our results demonstrate that the issue of enemy recognition may be viewed as a complex of both aggressive and post-presentation behaviours.     

Caspase cleavage product of BAP31 induces mitochondrial fission through endoplasmic reticulum calcium signals,enhancing cytochrome c release to the cytosol

Stimulation of cell surface death receptors activates caspase-8, which targets a limited number of substrates including BAP31, an integral membrane protein of the endoplasmic reticulum (ER). Recently, we reported that a caspase-resistant BAP31 mutant inhibited several features of Fas-induced apoptosis, including the release of cytochrome c (cyt.c) from mitochondria (Nguyen, M., D.G. Breckenridge, A. Ducret, and G.C. Shore. 2000. Mol. Cell. Biol. 20:6731-6740), implicating ER-mitochondria crosstalk in this pathway. Here, we report that the p20 caspase cleavage fragment of BAP31 can direct pro-apoptotic signals between the ER and mitochondria. Adenoviral expression of p20 caused an early release of Ca2+ from the ER, concomitant uptake of Ca2+ into mitochondria, and mitochondrial recruitment of Drp1, a dynamin-related protein that mediates scission of the outer mitochondrial membrane, resulting in dramatic fragmentation and fission of the mitochondrial network. Inhibition of Drp1 or ER-mitochondrial Ca2+ signaling prevented p20-induced fission of mitochondria. p20 strongly sensitized mitochondria to caspase-8-induced cyt.c release, whereas prolonged expression of p20 on its own ultimately induced caspase activation and apoptosis through the mitochondrial apoptosome stress pathway. Therefore, caspase-8 cleavage of BAP31 at the ER stimulates Ca2+-dependent mitochondrial fission, enhancing the release of cyt.c in response to this initiator caspase.     

Soybean hull peroxidase immobilization on macroporous glycidyl methacrylates with different surface characteristics

Soybean hull peroxidase (SHP, E.C. 1.11.1.7) was immobilized by a glutaraldehyde and periodate method onto series of macroporous copolymers of glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA), poly(GMA-co-EGDMA) with various surface characteristics and pore size diameters ranging from 44 to 200 nm. Glutaraldehyde immobilization method and poly(GMA-co-EGDMA) named SGE 20/12 with pore sizes of 120 nm gave immobilized enzyme with highest specific activity of 25 U/g. Deactivation studies showed that immobilization increased stability of SHP and that surface characteristics of the used copolymer had a major influence on a stability of immobilized enzyme at high temperatures and in an organic solvent. The highest thermostability was obtained using the copolymer SGE 20/12 with pore size of 120 nm, while the highest stability in dioxane had SHP immobilized onto copolymer SGE 10/4 with pore size of 44 nm. Immobilized SHP showed a wider pH optimum as compared to the native enzyme especially at alkaline pH values and 3.2 times increased K _m value for pyrogallol. After 6 cycles of repeated use in batch reactor, immobilized SHP retained 25 % of its original activity. Macroporous copolymers with different surface characteristics can be used for fine tuning of activity and stability of immobilized SHP to obtain a biocatalyst suitable for phenol oxidation or polymer synthesis in organic solvents.     

Retinitis pigmentosa rhodopsin mutations L125R and A164V perturb critical interhelical interactions: new insights through compensatory mutations and crystal structure analysis

L125R, a severe retinitis pigmentosa rhodopsin missense mutation, results in rhodopsin protein misfolding, retinal degeneration, and ultimately blindness. The initiating structural events leading to this protein misfolding are unknown. Through the use of compensatory mutations, in conjunction with crystal structure-based molecular analysis, we established that the larger and positively charged Arg replacing Leu125 sterically hinders both the adjacent Trp126 and a critical interhelical interaction between transmembrane III (TM III) and transmembrane V (TM V; Glu122 and His211 salt bridge). Further, analysis of another retinitis pigmentosa mutation, A164V (TM IV), indicates that the larger Val interferes with residues Leu119 and Ile123 on TM III, leading to the disruption of the same critical Glu122-His211 salt bridge (TM III-TM V interaction). Combined, these localized defects in interhelical interactions cause structural changes that interfere with the ability of opsin to bind 11-cis-retinal. These distortions ultimately lead to the formation of an abnormal disulfide bond, severe protein instability, aggregation, and endoplasmic reticulum retention. In the absence of a crystal or NMR structure of each retinitis pigmentosa mutation, compensatory mutagenesis and crystal structure-based analysis are powerful tools in determining the localized molecular disturbances. A detailed understanding of the initiating local perturbations created by missense mutations such as these, not only identifies critical factors required for correct folding and stability, but additionally opens avenues for rational drug design, mimicking the compensatory mutations and stabilizing the protein.     

In Vitro Antibacterial Activity of Cysteine Protease Inhibitor from Kiwifruit (Actinidia deliciosa)

The need for replacing traditional pesticides with alternative agents for the management of agricultural pathogens is rising worldwide. In this study, a cysteine proteinase inhibitor (CPI), 11 kDa in size, was purified from green kiwifruit to homogeneity. We examined the growth inhibition of three plant pathogenic Gram-negative bacterial strains by kiwi CPI and attempted to elucidate the potential mechanism of the growth inhibition. CPI influenced the growth of phytopathogenic bacteria Agrobacterium tumefaciens (76.2 % growth inhibition using 15 μM CPI), Burkholderia cepacia (75.6 % growth inhibition) and, to a lesser extent, Erwinia carotovora (44.4 % growth inhibition) by inhibiting proteinases that are excreted by these bacteria. Identification and characterization of natural plant defense molecules is the first step toward creation of improved methods for pest control based on naturally occurring molecules.     

Identification of Novel Genetic Alterations in Samples of Malignant Glioma Patients

Glioblastoma is the most frequent and malignant human brain tumor. High level of genomic instability detected in glioma cells implies that numerous genetic alterations accumulate during glioma pathogenesis. We investigated alterations in AP-PCR DNA profiles of 30 glioma patients, and detected specific changes in 11 genes not previously associated with this disease: LHFPL3, SGCG, HTR4, ITGB1, CPS1, PROS1, GP2, KCNG2, PDE4D, KIR3DL3, and INPP5A. Further correlations revealed that 8 genes might play important role in pathogenesis of glial tumors, while changes in GP2, KCNG2 and KIR3DL3 should be considered as passenger mutations, consequence of high level of genomic instability. Identified genes have a significant role in signal transduction or cell adhesion, which are important processes for cancer development and progression. According to our results, LHFPL3 might be characteristic of primary glioblastoma, SGCG, HTR4, ITGB1, CPS1, PROS1 and INPP5A were detected predominantly in anaplastic astrocytoma, suggesting their role in progression of secondary glioblastoma, while alterations of PDE4D seem to have important role in development of both glioblastoma subtypes. Some of the identified genes showed significant association with p53, p16, and EGFR, but there was no significant correlation between loss of PTEN and any of identified genes. In conclusion our study revealed genetic alterations that were not previously associated with glioma pathogenesis and could be potentially used as molecular markers of different glioblastoma subtypes.