The effects of DDT upon flat and vesicular bilayers studied by a fluorescent probe

The effect of DDT and several analogs upon bilayer membranes was studied, using the fluorescent dye di (octadecyl)oxycarbocyanin as a probe. It was shown in flat bilayers of Torpedo electroplax phospholipids, using fluorescence correlation spectroscopy, that neither DDT nor its physiologically inactive analog, p,p′-hydroxy-DDT, affected the fluidity of the membrane. However DDT, and not the analog, displaced half of the dye from the membrane. In studies with lecithin or Torpedo electroplax phospholipid vesicles, using simple fluorescence measurements, no displacement of the dye was observed by DDT or its analogs.     

Studies of Partial Amino Acid Sequences of γ‐40k Secalins of Rye

Though γ‐40k secalins are a major protein type within rye storage proteins, total amino acid sequences are not as well known as the gluten proteins of wheat. Well‐reputed structural features such as amino acid compositions and molecular masses indicated a close relationship between γ‐40k secalins and γ‐gliadins of wheat, but the degree of homology of amino acid sequences and the positions of intramolecular disulfide bonds are unknown. Therefore, two major components of γ‐40k secalins (R1, R2) were analyzed for partial amino acid sequences. The R1 and R2, derivatized with 4‐vinylpyridine, were isolated from the prolamin fraction of rye cultivar Danko by means of a two‐step RP‐HPLC on C₁₈ silica gel. The proteins were digested in parallel with trypsin and thermolysin, and the partial hydrolyzates were separated by RP‐HPLC. Simultaneous measurement of UV absorbance at 210 and 254 nm allowed the detection of all peptides eluted as well as the specific detection of pyridylethylated cysteine peptides. Isolated peptides were characterized by sequence analysis, and in parts by mass spectrometry, and assigned to known sequences of γ‐gliadins. The results demonstrated that the N‐terminal domain of R1 and R2 remained undigested after tryptic hydrolysis; they were in agreement with the N‐terminal domain of γ‐gliadins in their molecular masses and in the absence of cysteine residues. Most of the isolated peptides originated from the C‐terminal domains, they covered 83% (R1) and 77% (R2), respectively, of the C‐terminal domain of a known γ‐gliadin (clone pW1020). Comparison of R1 and R2 revealed differences only in a few sequence positions. The degree of homology between the C‐terminal domains present in γ‐40k secalins and γ‐gliadins was ≈85%. All eight cysteine residues of γ‐gliadins were found in R1 and R2 sequences. Remarkably, sequences close to corresponding cysteine residues were identical for γ‐40k secalins and γ‐gliadins. Therefore, it can be assumed that the positions of intramolecular disulfide links are homologous.     

萝卜-甘蓝型油菜中萝卜基因组的RAPD与dpRAPD分析效率研究

应用RAPD与dpRAPD方法鉴定萝卜-甘蓝型油莱中萝卜基因组,筛选了140条随机引物。结果表明,平均每条引物(组合)能产生的萝b基因组特异标记数dpRAPD高于RAPD,分别为1．69和1．33;在dpRAPD扩增产物中有77．6％谱带清晰易辨,略高于RAPD(75．4％)。两者所检测到的萝卜基因组标记大部分为各自特异的扩增产物。由于结合了荧光标记引物,dpRAPD反应产物可在Genetic Analyzer上分离检测,因此能检测到100bp以下的小片段DNA。     

Prevalence of Mycobacterium bovis skin positivity and associated risk factors in cattle from Western Uganda

Purpose

A cross-sectional study was undertaken to determine the prevalence of Mycobacterium bovis skin positivity and associated risk factors in cattle in western Uganda.

Methods

Herds were selected using multi-stage cluster sampling. The comparative cervical intradermal tuberculin test (CCT) was used to determine cattle tuberculosis status using US Department of Agriculture protocols. Risk factor data were collected from cattle owners through questionnaires collected by in-person interviews. Multivariable logistic regression models were used to measure the association between risk factors and herd CCT reactor prevalence.

Results

A total of 525 cattle from 63 herds were screened for M. bovis infection. Of the 525 cattle tested, 2.1 % were CCT reactors and 15.43 % were CCT suspects. Of herds tested, 14.28 % had at least 1 CCT reactor. Using a private water source for cattle and not introducing new cattle into the farm were associated with lower prevalence of M. bovis skin positivity. The herd-level prevalence of M. bovis reactors in Kashaari County of Mbarara District was 14.5 %, and the individual cattle prevalence was low (2.1 %).

Conclusions

Using communal sources of drinking water for cattle and introducing new cattle on the farm were farm management practices associated with increased risk of M. bovis exposure in cattle. Despite the low prevalence of bovine tuberculosis (TB), there is a need to educate the populace on the possibility of human infection with zoonotic TB and for educating farmers on practices to reduce the risk of acquiring M. bovis in the Mbarara District.     

Mitochondrial FtsZ in a chromophyte alga

A homolog of the bacterial cell division gene ftsZ was isolated from the alga Mallomonas splendens. The nuclear-encoded protein (MsFtsZ-mt) was closely related to FtsZs of the alpha-proteobacteria, possessed a mitochondrial targeting signal, and localized in a pattern consistent with a role in mitochondrial division. Although FtsZs are known to act in the division of chloroplasts, MsFtsZ-mt appears to be a mitochondrial FtsZ and may represent a mitochondrial division protein.     

Reduced competition and altered feeding behavior among marine snails after a mass extinction

Extinction may alter competitive interactions among surviving species, affecting their subsequent recovery and evolution, but these processes remain poorly understood. Analysis of predation traces produced by shell-drilling muricid snails on bivalve prey reveals that species interactions were substantially different before and after a Plio-Pleistocene mass extinction in the western Atlantic. Muricids edge- and wall-drilled their prey in the Pliocene, but Pleistocene and Recent snails attacked prey only through the shell wall. Experiments with living animals suggest that intense competition induces muricid snails to attack shell edges. Pliocene predators, therefore, probably competed for resources more intensely than their post-extinction counterparts.     

Podzol: Soil of the Year 2007. A review on its genesis,occurrence, and functions

The Podzol has been elected “Soil of the year 2007” in Germany. This article reviews the present knowledge on the development, functions, and threats of Podzols. The main theories on mobilization and transport of organic matter, Fe, Al, and Si are (1) metal‐organic migration, (2) metal reduction, and (3) inorganic sol migration. Immobilization theories include precipitation or polymerization due to increasing pH/abundance of base cations with depth, mechanical filtering in soil pores, oxidation of metal‐organic complexes, biodegradation of the organic part, decreasing C‐to‐metal ratios during translocation, adsorption to soil particles, and flocculation at the point of zero charge. Podzolization is discussed also on the catena scale, where vertical and lateral translocation processes (across pedon boundaries) need to be considered to understand Podzol patterns in landscapes. Chronosequence studies show that incipient podzolization usually becomes visible between 100 and 500 y and mature Podzols develop in 1,000–6,000 y. The occurrence of Podzols worldwide is concentrated mainly on the boreal zone and mountain regions within the humid temperate zone. Smaller Podzol areas are found in some perhumid tropical and subtropical regions. In Germany, Podzols occur in the Alps, in the glaciofluvial valleys and heathlands of N Germany, and in the mountain ranges. They fulfil several ecological functions, especially for groundwater recharge. Main threats for these mostly sandy soils are wind erosion and surface mining of sand. Two pedons which were chosen to represent the “Soil of the year 2007” are presented. Finally, some conclusions about podzolization processes are drawn, which may explain the diverse observations reported in the literature.     

The relationship between Sr and Ca accumulation in the major constituents of a terrestrial community resident on a celestitic (Sr SO4) soil in S.W. England

The accumulation and depuration of Ca and Sr were measured in populations of the earthworm Lumbricus rubellus, originating from calcareous and acidic soils, following laboratory exposure to a Sr-rich soil and a control soil. Populations from acidic soils accumulated more Sr than those from calcareous soils, when placed in a Sr-rich soil. After transferal from a Sr-rich soil to Sr-free soil, all populations depurated the majority of their body Sr (84 %-96 %) whilst maintaining their body Ca concentration; the Sr excretion was greater in the populations originating from acidic soils. ICP-MS cation analysis demonstrated the majority of Ca and Sr to be located in anterior alimentary canal and the majority of Sr was lost from this region.