Conversion of the BASE prion strain into the BSE strain: the origin of BSE?

Atypical neuropathological and molecular phenotypes of bovine spongiform encephalopathy (BSE) have recently been identified in different countries. One of these phenotypes, named bovine "amyloidotic" spongiform encephalopathy (BASE), differs from classical BSE for the occurrence of a distinct type of the disease-associated prion protein (PrP), termed PrP(Sc), and the presence of PrP amyloid plaques. Here, we show that the agents responsible for BSE and BASE possess different biological properties upon transmission to transgenic mice expressing bovine PrP and inbred lines of nontransgenic mice. Strikingly, serial passages of the BASE strain to nontransgenic mice induced a neuropathological and molecular disease phenotype indistinguishable from that of BSE-infected mice. The existence of more than one agent associated with prion disease in cattle and the ability of the BASE strain to convert into the BSE strain may have important implications with respect to the origin of BSE and spongiform encephalopathies in other species, including humans.     

Production of β-carotene by aRhodotorula strain

Summary The production of -carotene by the biomass ofRhodotorula strain var.glutinis, during the stationary phase of growth and in non-proliferating conditions was assayed. When the cells were transferred to distilled water, the fraction of -carotene produced increased from 130 to 630 g per gram of dried cells.     

Computer modelling of bone’s adaptation: the role of normal strain,shear strain and fluid flow

Bone loss is a serious health problem. In vivo studies have found that mechanical stimulation may inhibit bone loss as elevated strain in bone induces osteogenesis, i.e. new bone formation. However, the exact relationship between mechanical environment and osteogenesis is less clear. Normal strain is considered as a prime stimulus of osteogenic activity; however, there are some instances in the literature where osteogenesis is observed in the vicinity of minimal normal strain, specifically near the neutral axis of bending in long bones. It suggests that osteogenesis may also be induced by other or secondary components of mechanical environment such as shear strain or canalicular fluid flow. As it is evident from the literature, shear strain and fluid flow can be potent stimuli of osteogenesis. This study presents a computational model to investigate the roles of these stimuli in bone adaptation. The model assumes that bone formation rate is roughly proportional to the normal, shear and fluid shear strain energy density above their osteogenic thresholds. In vivo osteogenesis due to cyclic cantilever bending of a murine tibia has been simulated. The model predicts results close to experimental findings when normal strain, and shear strain or fluid shear were combined. This study also gives a new perspective on the relation between osteogenic potential of micro-level fluid shear and that of macro-level bending shear. Attempts to establish such relations among the components of mechanical environment and corresponding osteogenesis may ultimately aid in the development of effective approaches to mitigating bone loss.     

EIIaCre – Utility of a general deleter strain

Transgenic Research -     

Intraspecific variation in parasites- what is a strain?

The use of molecular techniques in parasitology has revealed a startling degree of diversity within species of parasite. These discoveries have emphasized the need for parasitologists to define and describe accurately the organisms with which they work. Andrew Thompson and Alan Lymbery propose that parasite strains be described by a combination of genetic and biological characteristics since reliance on the genotype alone may confer significance on a feature of little biological relevance.     

猪源乳杆菌Lactobacillus reuteri strain DSM和Lactobacillus taiwanensis strain BCRC对肠道炎症的影响

[目的] 旨在以葡聚糖硫酸钠（DSS）诱导小鼠肠炎模型研究猪源乳杆菌Lactobacillus reuteri strain DSM（LR）和Lactobacillus taiwanensis strain BCRC（LT）对肠道炎症的影响。[方法] 选取24只8周龄体重相近的C57BL/6J雄性小鼠,随机分为4组（每组6个重复）：正常对照组、DSS组、LR菌处理组（DSS+LR）和LT菌处理组（DSS+LT）。适应期7 d,试验期16 d,随后处死小鼠并采样。[结果] 与正常对照组相比,DSS组小鼠体重、结肠长度显著降低,疾病活动指数（DAI）显著增加（P<0.05）;与DSS组相比,LR、LT菌处理组小鼠体重下降的程度并没有显著缓解,但是,其DAI评分显著降低;并且,LT菌处理组结肠长度显著增加（P<0.05）。正常对照组和LT菌处理组结肠组织病理学评分显著低于DSS组和LR菌处理组（P<0.05）。结肠髓过氧化物酶（MPO）活性在正常对照组和LT菌处理组也显著低于DSS组（P<0.05）,在LR菌处理组与DSS组无显著差异（P>0.05）。与正常对照组相比,DSS组结肠和血浆的促炎因子TNF-α、IL-1β、IL-6水平显著升高,而抗炎因子IL-10水平显著降低;相比于DSS组,LT菌处理组显著降低了结肠和血浆的TNF-α、IL-1β、IL-6水平,升高了IL-10水平;LR菌处理组显著降低了结肠TNF-α水平、血浆IL-1β水平,升高IL-10水平（P<0.05）。免疫组化和ELISA结果显示,相比于正常对照组,DSS组降低了结肠紧密连接蛋白Claudin-1、Occludin、ZO-1和黏蛋白Muc-2表达水平,而LR或LT菌的处理则上调了DSS影响下的屏障相关蛋白表达。16S rDNA测序技术检测结肠菌群组成,PCoA分析得出,正常对照组和DSS组显著分离,LT处理组菌群组成更接近于正常对照组。门水平上,变形菌门丰度在正常对照组显著低于DSS组（P<0.05）;与DSS组相比,LT菌处理组也能降低变形菌门丰度,但未达显著水平（P>0.05）。属水平上,Muribaculaceae_norank属在正常对照组显著高于其他3组,Bacteroides在正常对照组显著低于其他3组（P<0.05）;与DSS组相比,LR或LT菌的处理增加了Muribaculaceae_norank丰度,降低了Bacteroides菌丰度,但差异不显著（P>0.05）。[结论] 乳杆菌Lactobacillus reuteri和Lactobacillus taiwanensis能增强肠上皮屏障,对DSS引起的肠道炎症起到了一定的缓解作用;其中,Lactobacillus taiwanensis对肠上皮屏障的保护效果更为明显。     

Use of speckle-tracking echocardiography–derived strain and systolic strain rate measurements to predict rejection in transplant hearts with preserved ejection fraction

Background

Noninvasive diagnosis of allograft rejection in heart transplant recipients is challenging. The utility of 2-dimensional speckle-tracking echocardiography (2D-STE) to predict severe rejection in heart transplant recipients with preserved left ventricular ejection fraction (LVEF) was evaluated.

Methods

Adult heart transplant patients with preserved LVEF (>?55%) and severe rejection by biopsy (Rejection Grade?≥?2R) or no rejection between 1997 and 2011 at the Mayo Clinic in Rochester, Minnesota were evaluated. Transthoracic echocardiography was performed within 1?month of the biopsy. LV global longitudinal and circumferential strain and strain rates (GLS, GLSR, GCS, and GCSR) were analyzed retrospectively.

Results

Of 65 patients included, 25 had severe rejection and 40 were normal transplant controls without rejection. Both groups had more men than women (64 and 75%, respectively). Baseline clinical variables were similar between the groups. Both groups had normal LVEF (64.3% vs 64.5%; P?=?.87). All non-strain echocardiographic variables were similar between the 2 groups. Strain analysis showed significantly increased early diastolic longitudinal strain rate (P?=?.02) and decreased GCS (P?<?.001) and GCSR (P?=?.02) for the rejection group compared with the control group. The area under the receiver operating characteristic curve for GCS was 0.77. With a GCS cutoff of ??17.60%, the sensitivity and specificity of GCS to detect severe acute rejection were 81.8 and 68.4%, respectively.

Conclusions

2D-STE may be useful in detecting severe transplant rejection in heart transplant patients with normal LVEF.

     

Genome sequence of Streptomyces sp. strain Tü6071

Streptomyces sp. Tü6071 is a soil-dwelling bacterium which has a highly active isoprenoid biosynthesis. Isoprenoids are important precursors for biopharmaceutical molecules such as antibiotics or anticancer agents, e.g., landomycin. Streptomyces sp. Tü6071 produces the industrially important terpene glycosides phenalinolactones, which have antibacterial activity against several Gram-positive bacteria. The availability of the genome sequence of Streptomyces sp. Tü6071 allows for understanding the biosynthesis of these pharmaceutical molecules and will facilitate rational genome modification to improve industrial use.     

Can a 'flawless' live vector vaccine strain be engineered?

The efficiency of any live bacterial vector vaccine hinges on its ability to present sufficient foreign antigen to the human immune system to initiate the desired protective immune response(s). However, synthesis of sufficient levels of heterologous antigen can result in an increase in metabolic burden with an accompanying decrease in the fitness of the live vector, which can ultimately lower desired immune responses to both live vector and heterologous antigen. Here, we explore the underlying mechanisms of metabolic load and propose ways of minimizing such burdens to enhance the fitness and immunogenicity of Salmonella-based live vector vaccines.     

Characterization of a novel β-glucosidase from a Stachybotrys strain

An improved mutant was isolated from the cellulolytic fungus Stachybotrys sp. after nitrous acid mutagenesis. It was fed-batch cultivated on cellulose and its extracellular cellulases (mainly the endoglucanases and β-glucosidases) were analyzed. One β-glucosidase was purified to homogeneity after two steps, MonoQ and gel filtration and shown to be a dimeric protein. The molecular weight of each monomer is 85 kDa. Besides its aryl β-glucosidase activity towards salicin, methyl-umbellypheryl-β-d-glucoside (MUG) and p-nitrophenyl-β-d-glucoside (pNPG), it showed a true β-glucosidase activity since it splits cellobiose into two glucose monomers. The V_max and the K_m kinetics parameters with pNPG as substrate were 78 U/mg and 0.27 mM, respectively. The enzyme shows more affinity to pNPG than cellobiose and salicin whose apparent values of K_m were, respectively, 2.22 and 37.14 mM. This enzyme exhibits its optimal activity at pH 5 and at 50 °C. Interestingly, this activity is not affected by denaturing gel conditions (SDS and β-mercaptoethanol) as long as it is not pre-heated. The N-terminal sequence of the purified enzyme showed a significant homology with the family 1 β-glucosidases of Trichoderma reesei and Humicola isolens even though these two enzymes are much smaller in size.     

16α-hydroxylation of progesterone by a strain ofactinomyces globosus

В систематическое исследование трансформации свойств Actinomycetes было было установлено, что 17 из 76 видов тестировани е преобразованы прогестерон по 16 га-гидрокси -п рогестерона. Оптимальные условия для этой трансформац ии были изучены этой трансформации б ыли изучены следующие результат ы:

1. (1)
   Оптимальное рН для данного типа трансформации была 6–7. На нижней hydroxylation ценностей была меш ает.     
   
   

The sarcomeric cytoskeleton: who picks up the strain?

In striated muscle sarcomeres, the contractile actin and myosin filaments are organised by a subset of specialised cytoskeletal proteins, the sarcomeric cytoskeleton. They include α-actinin, myomesin, and the giant proteins titin, obscurin and nebulin, which combine architectural, mechanical and signalling functions. Mechanics and signalling in the sarcomere appear tightly interdependent, but the exact contributions of the various sarcomeric cytoskeleton proteins to strain handling or signalling are only just emerging. General mechanisms of cytoskeletal mechanics and signalling may be gleaned from the sarcomere as a specialised actomyosin system. Recent work has led to insight into the interactions, structure, and mechanical stability of sarcomeric protein complexes that fulfil both structural and signalling roles.     

Why did the Fleming strain fail in penicillin industry?

Penicillin, discovered 75 years ago by Sir Alexander Fleming in Penicillium notatum, laid the foundations of modern antibiotic chemotherapy. Early work was carried out on the original Fleming strain, but it was later replaced by overproducing strains of Penicillium chrysogenum, which became the industrial penicillin producers. We show how a C(1357)-->T (A394V) change in the gene encoding PahA in P. chrysogenum may help to explain the drawback of P. notatum. PahA is a cytochrome P450 enzyme involved in the catabolism of phenylacetic acid (PA; a precursor of penicillin G). We expressed the pahA gene from P. notatum in P. chrysogenum obtaining transformants able to metabolize PA (P. chrysogenum does not), and observing penicillin production levels about fivefold lower than that of the parental strain. Our data thus show that a loss of function in P. chrysogenum PahA is directly related to penicillin overproduction, and support the historic choice of P. chrysogenum as the industrial producer of penicillin.     

Nitrite reduction in Rhizobium “hedysari” strain HCNT 1

Rhizobium hedysari strain HCNT 1 rapidly reduced nitrite to N₂O, only slowly reduced nitrate to nitrite and did not exhibit nitrous oxide reductase activity. Nitrite reduction in this rhizobium strain may be a detoxification mechanism for conversion of nitrite, which inhibits O₂ uptake, to non-toxic N₂O. Concentrations of nitrite as small as 3 M diminished O₂ uptake in whole cells. The bacterium did not couple energy conservation with nitrate or nitrite reduction. Cells neither grew anaerobically at the expense of these nitrogen oxides nor translocated protons during reduction of nitrite. Induction of nitrite reductase activity was not a response to the presence of nitrate or nitrite, but occurred instead when the O₂ concentration in culture atmospheres fell to <16.5% of air saturation. Sensitivity of cytochrome o, which is synthesized only in cells grown under O₂-limited conditions, may account for the toxicity of nitrite in strain HCNT 1.     

Asian (Taiwan) Taenia: species or strain?

Recent studies on the epidemoiological pattern of taenisis in Southeast Asia have indicated the existence of a third form of human Taenia which is distinguishable from Taenia saginata and T. solium. Don McManus and Josephine Bowles here review how new genetic evidence supports earlier conclusions that the Asian Taenia is a distinct entity but is closely related T. saginata, and suggests its taxonomic classification as a subspecies or strain of T. saginata is more appropriate than formal designation as a new species.     

Leishmania infantum tropism: strain genotype or host immune status?

In apparently immunocompetent patients, Leishmania infantum provokes a spectrum of disease, ranging from simple skin lesion to severe visceral leishmaniasis, that is determined mainly by the protozoan genotype. In HIV-positive individuals, leishmanial infection results almost exclusively in visceral disease. In this review, Luigi Grodoni and Marina Gromiccia discuss the role o f the intrinsic virulence of L. infantum strains and the immune condition of the host, and focus on recently described mechanisms of immunological control of leishmanial infection.     

β-carotene from the abscisic acid producing strain of Cercospora rosicola

-carotene was isolated from an extract of Cercospora rosicola mycelia and identified on the basis of chromatographic properties and UV-visible spectroscopic evidence. The accumulation of -carotene was inhibited 71 and 52% by 10 M amounts of decylimidazole and fluridone, resepectively. Abscisic acid accumulation was inhibited 63% by decylimidazole and enhanced about 10% by fluridone. Several other inhibitors of carotenoid synthesis failed to inhibit ABA biosynthesis.