Effects of Bark Beetle Disturbance on Soil Nutrient Retention and Lake Chemistry in Glacial Catchment

Ecosystems - Forest ecosystems worldwide are subjected to human-induced stressors, including eutrophication and acidification, and to natural disturbances (for example, insect infestation,...     

Effect of protein kinase inhibitors on protein phosphorylation and germination of aerial spores from<Emphasis Type="Italic">Streptomyces coelicolor</Emphasis>

In vitro phosphorylation reaction using extracts prepared from cells in the exponential phase of growth and aerial spores of Streptomyces coelicolor displayed the presence of multiply phosphorylated proteins. Effect of protein kinase inhibitors (PKIs) (geldanamycin, wortmannin, apigenin, genistein, roscovitine, methyl 2,5-dihydroxycinnamate, rapamycin, staurosporine) was determined on protein phosphorylation and on germination of spores. The in vitro experiments showed differences in phosphoprotein pattern due to the presence of PKIs. Cultivation of aerial spores with PKIs led to a significant delay in germ tube emergence and filament formation. However, none of the tested PKIs completely blocked the germination process. These results indicate that protein kinases of spores form complex networks sharing common modulating site that plays an important role in proper timing of early developmental events.     

Red-shifted light-harvesting system of freshwater eukaryotic alga Trachydiscus minutus (Eustigmatophyta,Stramenopila)

Photosynthesis Research - Survival of phototrophic organisms depends on their ability to collect and convert enough light energy to support their metabolism. Phototrophs can extend their absorption...     

Characterization of the rplB gene from Streptomyces collinus and its protein product by mass spectrometry

Ribosomal protein L2 is the largest protein components of 50S subunits. The protein is implicated in peptidyl transferase activity and binds to functionally important domains of 23S rRNA. The rplB gene, which codes for ribosomal protein L2 was cloned from Streptomyces collinus. The gene rplB was isolated from BamHI fragment (3.0 kb) of chromosomal DNA possessing two partial and four complete ORF's in the order from 5' to 3': rplC, rplD, rplW, rplB, rpsS, and rplV. The gene organization corresponds to the S10 operon. Gene rplB (834 bp) encodes a polypeptide chain of 278 amino acids. The molecular mass calculated from genomic structure is 30.5 kDa and pI 11.87. Protein L2 is rich in positively charged amino acids (Arg 36, Lys 20, and His 11). N-terminal domain possesses topology similar to the oligonucleotide/oligosaccharide binding OB folds. The availability of genome sequence makes it possible to identify L2 protein by mass spectrometry, moreover it facilitates the characterization of its potential posttranslational modifications. To confirm the protein sequence derived from the rplB gene the tryptic peptides of L2 were analyzed by mass spectrometric techniques. The obtained data matched exactly with the results of DNA sequencing.     

Effect of temperature and guanidine hydrochloride on ferrocytochrome<Emphasis Type="Italic"> c</Emphasis> at neutral pH

Thermally denatured horse heart ferrocytochrome c (ferrocyt c) has been characterized using absorption spectroscopy, differential scanning calorimetry (DSC) and viscometry at pH 7.0. DSC experiments have yielded the transition temperature of denaturant-free ferrocyt c unfolding as 100.6±0.3 °C, indicating an extremely high stability of the protein. The presence of guanidine hydrochloride (GdnHCl) facilitated estimation of the structural features of thermally unfolded ferrocyt c. The stability of the protein, expressed by G _D at 25 °C, is 59±5 kJ mol^–1 (DSC) and 65±6 kJ mol^–1 (absorption spectroscopy). An absorption spectrum of ferrocyt c demonstrates that the heme occurs in the high-spin state at extreme denaturing conditions (94 °C, 6.6 M GdnHCl). Absorption spectroscopy, using heme as a probe, shows that thermal denaturation of ferrocyt c occurs as a transition from a native low-spin (Met80/His18) to a high-spin disordered state with involvement of non-native, low-spin (bis-His) species.Abbreviations CD circular dichroism - cyt c cytochrome c - DSC differential scanning calorimetry - ferricyt c ferricytochrome c - ferrocyt c ferrocytochrome c - GdnHCl guanidine hydrochloride - NHE normal hydrogen electrode     

Epidermal growth factor-receptor tyrosine kinase activity regulates expansion of porcine oocyte-cumulus cell complexes in vitro

We have recently shown that epidermal growth factor (EGF) strongly stimulates expansion of porcine oocyte-cumulus complexes (OCCs) isolated from large follicles (>6 mm) and does not promote expansion of OCCs from small (3-4-mm) follicles. In order to elucidate the role of EGF in OCCs expansion, in the present study, we first examined the presence of EGF receptors (EGFRs) in cumulus cells isolated from follicles of different sizes. Surprisingly, immunoblotting showed that cumulus cells obtained from all follicular size categories contained similar amounts of EGFR protein. On the other hand, we found a dramatic difference in the pattern of protein tyrosine phosphorylation in a comparison of cumulus cells isolated from small and large follicles treated by EGF. Furthermore, tyrosine-phosphorylated EGFR was specifically immunoprecipitated with antiphosphotyrosine antibodies from EGF-treated cumulus cells isolated from the large follicles. This result strongly indicates that only OCCs from the large follicles contain mature EGFRs that are capable of becoming activated by EGF. Remarkably, preincubation of cumulus cells from small follicles (3-4 mm) with FSH strongly increased EGF-stimulated tyrosine phosphorylation to levels comparable with OCCs from large follicles. The FSH-dependent activation of EGFRs was beneficial for expansion of OCCs isolated from the small follicles since OCCs treated sequentially by FSH (3 h) and EGF (1 h) underwent expansion significantly better then OCCs cultured in FSH or EGF alone. We conclude that a FSH-dependent pathway has an important role in the maturation of the EGFR in cumulus cells and that activation of EGFR-dependent signaling is sufficient to induce expansion.     

Antibodies against beta 2-glycoprotein I (beta 2-GP I) and their relationship to fetoplacental antigens

Binding of beta 2-GP I to anionic phospholipids is thought to be the major antigen required in the reaction of anticardiolipin antibodies to phospholipids. The aim of this study was to investigate the changes of anti-beta 2-GP I IgG during the first and second trimester of pregnancy and the relationship between the levels of anti-beta 2-GP I and fetoplacental antigens and the correlation between anti-beta 2-GP I IgG and antibodies against oxidized low-density lipoprotein IgG (oLAb) in serum of pregnant women. We determined anticardiolipin antibodies (ACA) IgG and maternal serum levels of alpha 1-fetoprotein (AFP), human chorionic gonadotrophin (HCG) and trophoblast-specific beta 1-glycoprotein (SP1) in 204 pregnant women in the first and second trimester. From this group we selected 52 serum samples positive for ACA IgG and 16 samples negative for ACA IgG. In the samples of selected patients, the levels of anti-beta 2-GP I IgG and oLAb IgG were determined. Anti-beta 2-GP I IgG levels significantly decreased in the second trimester (6.2+/-9.3 U/ml, mean +/- S.D.) in comparison with the first trimester (8.3+/-10.4 U/ml) (p=0.05). Multiple of median (MoM) AFP correlated negatively but not significantly in the first trimester with anti-beta 2-GP I (r = -0.261, p = 0.12). In the second trimester this correlation was significantly negative (r = -0.278, p = 0.04). The Spearman correlation coefficients for MoM HCG and anti-beta 2-GP I were 0.158 for the first trimester and 0.174 for the second trimester. MoM SP1 also did not correlate significantly with anti-beta 2-GP I in both trimesters. The correlation between anti-beta 2-GP I IgG and oLAb IgG was not significant (r = -0.06). In the first trimester 40 % serum samples were positive for anti-beta 2-GP I IgG and negative for oLAb IgG or vice versa, while 60 % samples in the second trimester were positive only for one determined autoantibody. We can conclude that the levels of anti-beta 2-GP I IgG decrease during the second trimester probably as the result of the effects of some immunosuppressive agents associated with pregnancy. The finding of negative correlation between AFP and anti-beta 2-GP I suggests that anti-beta 2-GP I has an influence on fetus development.     

Light and electron microscopic study of a Rickettsiella species from the cockroach Blatta orientalis

An infection with Rickettsiella sp. was responsible for an illness causing heavy body swelling in the Oriental cockroach Blatta orientalis. Reproduction of the colony stagnated. Vacuoles with parasitic bacteria occurred mainly in the fat body, but also in nearly all other organs, such as gut epithelium, Malpighian tubules, blood cells, and ovarioles. The parasites clearly differed from the symbiotic bacteria of the genus Blattabacterium, which regularly occur in the mycetocytes of B. orientalis. The vacuoles contained four stages of Rickettsiella: (1) infectious, electron-dense, rod-like elementary bodies (mean size 300 x 145 nm); (2) an electron-dense, flat intermedium stage, called flat body (mean size 515 x 255 x 125 nm); (3) an electron-light, spherical intermedium stage, called condensing sphere (mean size 340 nm); portions of cytoplasm condensed crescent-like at the border or in the center of the cell; and (4) large, spherical, electron-light initial bodies that multiplied by binary fission (mean size 600 nm). The initial bodies had a three-layered cell boundary, but all other stages had a five-layered cell boundary. Elementary and flat bodies contained an electron-light, oblique lamella and an oval structure with an array of ribosome-like granules, respectively. In contrast to other species of Rickettsiella, crystal formation or multiple division did not occur. The described species of Rickettsiella is different from "R. blattae," which belongs to the R. popilliae group. Instead, it shares more similarities with the R. chironomi group. To avoid confusion, it was provisionally named "R. crassificans."     

A new entomopoxvirus from a cockroach: light and electron microscopy

The cockroach entomopoxvirus caused a chronic infection in cultures of the German cockroach Blattella germanica. Heavily infected specimens showed a reduced mobility. Ellipsoid virus occlusion bodies (8 x 5 to 19 x 12 microm) were found intracellularly in tracheole cells, in the hypodermis, in fat body cells, and in muscles. Several hundred virus particles were integrated in a single occlusion body (OB), their long axis being oriented axially. Ovoid viroids measured 320 x 190 nm and possessed a unilateral, concave core and one lateral body. Starting occlusion, small granules attached to the virus particles which later transformed to a beaded, wavy envelope. An initial halo around the occluded virions disappeared in more central regions of the OB. Virus particles were formed either in a dense cytoplasmic area containing electron-dense viroids, or in a loosely aggregated viroplasm. In the latter, developmental stages were mainly represented by spheres with double membranes enclosing granular material. Spindles and larger crystal-like virus-free inclusion bodies occurred in the cytoplasm. The cytoplasm of infected cells appeared degenerated and the chromatin of the nuclei condensed at the periphery or disintegrated. Taxonomically, the described virus exhibits features of both EPV genus A and EPV genus B. Provisory it is named Blattella germanica EPV (BgEPV). A possible use of the cockroach EPV as a biological control agent is discussed.