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761.
Unintentional infection of laboratory rodents can compromise scientific research as well as the health of the animals and animal handlers. The source of contamination often is unknown, but may be introduced by wild rats from surrounding environments. To determine whether rats in Baltimore, Maryland, USA carry infectious agents commonly found in laboratory rodent colonies, we live-trapped 162 rats during 2005 to 2006 and screened them for a panel of viruses, bacteria and parasites. Antibodies against rat coronavirus/sialodacryoadenitis virus (91.7%), Mycoplasma pulmonis (72.9%), cilia-associated respiratory bacillus (52.1%), rat parvovirus/rat minute virus (29.2%), Kilham rat virus (10.4%), Toolan's H-1 virus (10.4%), Sendai virus (4.2%) and Theiler's mouse encephalomyelitis virus (4.2%), were detected in wild-caught Norway rats. Antibodies against reovirus and pneumonia virus of mice were not detected in wild Norway rats. Endoparasites, including Nippostrongylus braziliensis (71.6%), Rodentolepis nana or Hymenolepis diminuta (34.4%), Hetarakis spumosa (24.1%) and Trichuris muris (14.8%), as well as ectoparasites (14.8%), were identified in wild-caught rats. The risk of pathogen transmission from wild-caught rats to laboratory colonies needs to be mitigated by minimizing exposures rather than assuming wild animals represent a minimal hazard. 相似文献
762.
763.
Immunoglobulin heavy chains are polypeptides encoded by four genes: variable (IGHV), joining (IGHJ), diversity (IGHD), and constant (IGHC) region genes. The number of IGHV genes varies from species to species. To understand the evolution of the IGHV multigene family, we identified and analyzed the IGHV sequences from 16 vertebrate species. The results show that the numbers of functional and nonfunctional IGHV genes among different species are positively correlated. The number of IGHV genes is relatively stable in teleosts, but the intragenomic sequence variation is generally higher in teleosts than in tetrapods.
The IGHV genes in tetrapods can be classified into three phylogenetic clans (I, II, and III). The clan III and/or II genes are relatively
abundant, whereas clan I genes exist in small numbers or are absent in most species. The genomic organization of clan I, II,
and III IGHV genes varies considerably among species, but the entire IGHV locus seems to be conserved in the subtelomeric or near-centromeric region of chromosome. The presence or absence of specific
IGHV clan members and the lineage-specific expansion and contraction of IGHV genes indicate that the IGHV locus continues to evolve in a species-specific manner. Our results suggest that the evolution of IGHV multigene family is more complex than previously thought and that several factors may act synergistically for the development
of antibody repertoire.
Electronic supplementary materials The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
764.
765.
Accumulating evidence indicates that heregulins, EGF (epidermal growth factor)-like ligands, promote breast cancer cell proliferation and are involved in the progression of breast cancer towards an aggressive and invasive phenotype. However, there is limited information regarding the molecular mechanisms that mediate these effects. We have recently established that HRG (heregulin beta1) promotes breast cancer cell proliferation and migration via cross-talk with EGFR (EGF receptor) that involves the activation of the small GTPase Rac1. In the present paper we report that Rac1 is an essential player for mediating the induction of cyclin D1 and p21(Cip1) by HRG in breast cancer cells. Inhibition of Rac function by expressing either the Rac-GAP (GTPase-activating protein) beta2-chimaerin or the dominant-negative Rac mutant N17Rac1, or Rac1 depletion using RNAi (RNA interference), abolished the cyclin D1 and p21(Cip1) induction by HRG. Interestingly, the proliferative effect of HRG was impaired not only when the expression of Rac1 or cyclin D1 was inhibited, but also when cells were depleted of p21(Cip1) using RNAi. Inhibition of EGFR, PI3K (phosphoinositide 3-kinase; kinases required for Rac activation by HRG) or MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase] also blocked the up-regulation of cyclin D1 and p21(Cip1) by HRG. In addition, we found that HRG activates NF-kappaB (nuclear factor kappaB) in a Rac1- and MEK-dependent fashion, and inhibition of NF-kappaB abrogates cyclin D1/p21(Cip1) induction and proliferation by HRG. Taken together, these findings establish a central role for Rac1 in the control of HRG-induced breast cancer cell-cycle progression and proliferation through up-regulating the expression of cyclin D1 and p21(Cip1). 相似文献
766.
Egbert Strauß Andreas Grauer Martina Bartel Roland Klein Ludger Wenzelides Grit Greiser Alexander Muchin Heike Nösel Armin Winter 《European Journal of Wildlife Research》2008,54(1):142-147
The German Wildlife Information System, founded in 2001, is a long-term monitoring program documenting occurrence, number,
and development of game populations throughout Germany. Population numbers are recorded by standardized counting methods in
so-called reference areas. The population densities of the European hare are calculated by spotlight strip censuses in the
reference areas each spring and autumn all across Germany. From 2002 to 2005, the censuses were carried out by local hunters
in 510 to 676 reference areas each year. During these years, the calculated spring densities increased significantly from
11.0 (2002) to 14.5 hares/km2 (2005) nationwide. The overall increase in spring densities was primarily caused by the population rise from spring 2003
to 2004, which correlates with the high net growth rate in 2003. In 2005, the number of counted hares varied between less
than 1 and more than 107 hares/km2 in spring and between 0 and more than 170 hares/km2 in autumn. Because of differing landscapes in Germany, three regions were differentiated. In spring 2005, the average population
densities (median) in East Germany (5.4 hares/km2) and Southwest Germany (14.6 hares/km2) were significantly lower than in Northwest Germany (23.9 hares/km2). These regional differences had been similarly distinct in former years. 相似文献
767.
Template directed Layer-by-layer (LbL) technology recently moved into the center of scientific attention, particularly as a versatile tool for bioencapsulation purposes. Its major advantages can be found in the striking simplicity of tuning wall properties and the complete control over layer thickness and permeability. Yet, for the most commonly applied pair of polyelectrolytes, poly(allylamine) hydrochloride (PAH) and poly(styrene sulfonate) sodium salt (PSS), the mandatory control of the successful deposition on plane and colloidal surfaces is currently only attainable by means of sophisticated and expensive equipment. Here we describe an alternative quantification method based on a simple colorimetric assay using the Bradford reagent, a cost-effective commercially available dye, and standard laboratory technical devices. The binding of the dye to PSS causes a distinct shift of the absorption maximum from 465 to 680 nm, providing a method for spectral quantification of submicrogram amounts of dissolved PSS during LbL coating with significant accuracy and excellent reproducibility. The method was successfully employed to quantify accurate polyelectrolyte loadings on several particles that have a general importance as LbL templates. Thus, this method can be recommended as standard laboratory technique for control of LbL encapsulation and will considerably broaden the applicability of this promising technology in biotechnology. 相似文献
768.
Abdominal obesity is associated with metabolic risk factors for coronary heart disease (CHD). Although we previously found that using liposuction surgery to remove abdominal subcutaneous adipose tissue (SAT) did not result in metabolic benefits, it is possible that postoperative inflammation masked the beneficial effects. Therefore, this study provides a long-term evaluation of a cohort of subjects from our original study. Body composition and metabolic risk factors for CHD, including oral glucose tolerance, insulin resistance, plasma lipid profile, and blood pressure were evaluated in seven obese (39 +/- 2 kg/m(2)) women before and at 10, 27, and 84-208 weeks after large-volume liposuction. Liposuction surgery removed 9.4 +/- 1.8 kg of body fat (16 +/- 2% of total fat mass; 6.1 +/- 1.4 kg decrease in body weight), primarily from abdominal SAT; body composition and weight remained the same from 10 through 84-208 weeks. Metabolic endpoints (oral glucose tolerance, homeostasis model assessment of insulin resistance, blood pressure and plasma triglyceride (TG), high-density lipoprotein (HDL)-cholesterol, and low-density lipoprotein (LDL)-cholesterol concentrations) obtained at 10 through 208 weeks were not different from baseline and did not change over time. These data demonstrate that removal of a large amount of abdominal SAT by using liposuction does not improve CHD metabolic risk factors associated with abdominal obesity, despite a long-term reduction in body fat. 相似文献
769.
Klein S Grossmann R 《Journal of experimental zoology. Part A, Ecological genetics and physiology》2008,309(1):35-46
Recent studies of several avian species have shown that the primary sex ratio can change as a result of prevailing conditions, especially in the female bird's first reproductive season. In this study, we sought to determine the primary sex ratio of the first 15 eggs produced in chickens. The study compared chickens which had been commercially selected over many generations for egg-laying performance (Leghorns) with "fancy-bred" chickens selected for feather coloration. These fancy-bred chickens are known to reach reproductive maturity 4 weeks later than Leghorns. A group of precociously matured Leghorn chickens was produced by modification of diet and day length to investigate the effect of age at reproductive maturity on sex ratio. Sex diagnosis was performed on embryos which had died on or before embryonic day 10 by polymerase chain reaction (PCR). Living embryos were allowed to hatch before sex diagnosis. The group of precociously matured White Leghorns reached egg-laying age 3 weeks earlier than normal. In this group, the sex ratio of hatched chicks was in tendency skewed to females. In the White Leghorns maintained under normal conditions for commercial layers, sex ratio was balanced with a tendency to more males only in the first five eggs. In the group of fancy-bred chickens, the primary sex ratio was significantly biased toward more males and dependent on the laying sequence. Our data suggested a sex ratio bias toward males in the very first eggs at onset of reproduction in chickens depending on genetic background. 相似文献
770.
Eva Gross Birgit Busse Matthias Riemenschneider Steffi Neubauer Katharina Seck Hanns-Georg Klein Marion Kiechle Florian Lordick Alfons Meindl 《PloS one》2008,3(12)