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101.
N. I. Selin 《Russian Journal of Marine Biology》2009,35(2):183-185
The abundance of the predatory gastropod, the Far East dogwhelk Nucella heyseana in the Vostok Bay of the Sea of Japan was assessed by applying the mark and recapture technique with reverse sampling. It was shown that assessment of mollusk abundance using this approach did not differ significantly from that resulting from the frame technique. It was determined that the number of the dogwhelks decreased in recent years in the surveyed area. In implementing long-term research, including the seasonal dynamics of the number of N. heyseana and other mollusk species similar to it in their biology and behavior, we suggest applying, concurrently with the mark and recapture technique, other methods, enabling one to obtain more adequate figures of their numbers in the cold season. 相似文献
102.
Marco Berheide Stephanie Peper Selin Kara Wei Sing Long Steffen Schenkel Martina Pohl Bernd Niemeyer Andreas Liese 《Biotechnology and bioengineering》2010,106(1):18-26
Benzoylformate decarboxylase (BFD) from Pseudomonas putida is a thiamine diphosphate‐dependent (ThDP) enzyme that catalyzes the asymmetric C? C bond formation to (S)‐2‐hydroxypropiophenone [(S)‐HPP] starting from benzaldehyde and acetaldehyde. The enantioselectivity of BFD was shown to be a function of temperature and substrate concentration. It can additionally be changed by site‐directed mutagenesis on hot spot positions in the active site. In this article, we present the effect of hydrostatic pressure up to 250 MPa on the enantioselectivity for the recombinant wtBFD as well as for the variants BFD F464I, BFD A460I, and BFD A460I‐F464I. A general tendency toward lower amounts of (S)‐HPP could be observed at increasing pressures. For two of these variants an increase in pressure even caused an inversion in the enantioselectivity and thus increasing enantiomeric excesses, respectively. A pressure‐induced increase in enantioselectivity could therefore be observed for the first time in biocatalysis to the best of our knowledge. Furthermore, the pH is shown to be a parameter that also significantly influences the enantioselectivity of the reaction mentioned above. Biotechnol. Bioeng. 2010; 106: 18–26. © 2009 Wiley Periodicals, Inc. 相似文献
103.
Zu T. Shen Michael A. Brehm Keith A. Daniels Alexander B. Sigalov Liisa K. Selin Raymond M. Welsh Lawrence J. Stern 《The Journal of biological chemistry》2010,285(43):33144-33153
T cell cross-reactivity describes the phenomenon whereby a single T cell can recognize two or more different peptide antigens presented in complex with MHC proteins. Cross-reactive T cells have previously been characterized at the population level by cytokine secretion and MHC tetramer staining assays, but single-cell analysis is difficult or impossible using these methods. In this study, we describe development of a novel peptide-MHC heterodimer specific for cross-reactive T cells. MHC-peptide monomers were independently conjugated to hydrazide or aldehyde-containing cross-linkers using thiol-maleimide coupling at cysteine residues introduced into recombinant MHC heavy chain proteins. Hydrazone formation provided bi-specific MHC heterodimers carrying two different peptides. Using this approach we prepared heterodimers of the murine class I MHC protein H-2Kb carrying peptides from lymphocytic choriomeningitis virus and vaccinia virus, and used these to identify cross-reactive CD8+ T cells recognizing both lymphocytic choriomeningitis virus and vaccinia virus antigens. A similar strategy could be used to develop reagents to analyze cross-reactive T cell responses in humans. 相似文献
104.
N. I. Selin 《Russian Journal of Marine Biology》2010,36(1):26-33
In the summer of 2008, the abundance, local aggregation structure, growth rate, and life span of the gastropod Nucella freycineti inhabiting the littoral zone of Yankicha Island (Kuriles), which is affected by the postvolcanic activity of the Ushishir
Volcano were studied. The parameters varied within a wide range and appreciably depended on the distance mollusk populations
were from underwater and land gas-hydrothermal vents, which caused strong heating (up to 48°C) of cold sea waters and the
formation of an unusually acidic environment (pH approximately 3.5) in the Kraternaya Bay. The mollusks occurred at a water
temperature below 24°C and a pH above 4, but formed multiage populations at a temperature of 2–14°C and a pH of approximately
6.4–8.2. 相似文献
105.
106.
Several receptors are implicated in apoptotic cell (AC) uptake by phagocytic cells; however, their relative dominance in mammalian systems remains to be established. New studies shed light on the role of the phosphatidyl serine (PS) receptor (PSR). Ligation of PSR by PS on AC surfaces is considered essential for signaling uptake of ACs that are tethered to phagocytes via other receptors. 相似文献
107.
N. I. Selin 《Russian Journal of Marine Biology》2008,34(3):186-190
The relationships between the shell height of the predatory gastropod Cryptonatica janthostoma and the shell length of its typical prey, the bivalve Ruditapes philippinarum, and the diameter of the borehole on the prey shell resulting from a successful attack of the predator were experimentally found and assessed statistically. The shell height of C. janthostoma calculated retrospectively from the borehole diameter using the obtained relationships was 17–52 mm. The prey of C. janthostoma are burrowing bivalves, whose populations are affected by the predator to a varying degree. In populations of medium-sized mollusks (R. philippinarum, Protothaca euglypta, P. jedoensis, and others), C. janthostoma feeds on mollusks larger than 7–10 mm; in species with a shell length greater than 100 mm (Callista brevisiphonata, Saxidomus purpuratus), it eats specimens of 10–58 mm. C. janthostoma apparently has no effect on populations of small-sized mollusks (Anisocorbula venusta) and mollusks with an active avoidance response (Clinocardium californiense). 相似文献
108.
Memory T cells that are specific for one virus can become activated during infection with an unrelated heterologous virus, and might have roles in protective immunity and immunopathology. The course of each infection is influenced by the T-cell memory pool that has been laid down by a host's history of previous infections, and with each successive infection, T-cell memory to previously encountered agents is modified. Here, we discuss evidence from studies in mice and humans that shows the importance of this phenomenon in determining the outcome of infection. 相似文献
109.
CD8 T cell responses to viral infections in sequence 总被引:2,自引:0,他引:2
Our current understanding of virus-specific T cell responses has been shaped by model systems with mice, where naive animals are infected with a single viral pathogen. Paradigms derived from such models, however, may not always be applicable to a natural setting, where a host is exposed to numerous pathogens over its lifetime. Accumulating data in animal models and with some human diseases indicate that a host's prior history of infections can impact the specificity of future CD8 T cell responses, even to unrelated viruses. This can have both beneficial and detrimental consequences for the host, including altered clearance of virus, distinct forms of immunopathology, and substantial changes in the pool of memory T cells. Here we will describe the characteristics of CD8 T cells and the dynamics of their response to heterologous viral infections in sequence. 相似文献
110.
Infection of mice with a series of heterologous viruses causes a reduction of memory CD8(+) T cells specific to viruses from earlier infections, but the fate of the virus-specific memory CD4(+) T cell pool following multiple virus infections has been unknown. We have previously reported that the virus-specific CD4(+) Th precursor (Thp) frequency remains stable into long-term immunity following lymphocytic choriomeningitis virus (LCMV) infection. In this study, we questioned whether heterologous virus infections or injection with soluble protein CD4 Ags would impact this stable LCMV-specific CD4(+) Thp memory pool. Limiting dilution analyses for IL-2-producing cells and intracellular cytokine staining for IFN-gamma revealed that the LCMV-specific CD4(+) Thp frequency remains relatively stable following multiple heterologous virus infections or protein Ag immunizations, even under conditions that dramatically reduce the LCMV-specific CD8(+) CTL precursor frequency. These data indicate that the CD4(+) and CD8(+) memory T cell pools are regulated independently and that the loss in CD8(+) T cell memory following heterologous virus infections is not a consequence of a parallel loss in the memory CD4(+) T cell population. 相似文献