重组马g-干扰素抗病毒活性测定及单克隆抗体抑制活性鉴定

为了测定大肠杆菌和杆状病毒表达的重组马g-干扰素是否具有抗病毒活性, 利用这两种干扰素处理马胎肾细胞(EFK-78), 然后接种表达绿色荧光蛋白(GFP)的重组水泡性口炎病毒(VSV*GFP), 观察干扰素对病毒表达GFP的抑制, 测出其抗病毒活性单位分别为1×103 AU/mL、1×105 AU/mL。评价了制备的九株抗重组马g-干扰素单克隆抗体是否可抑制重组马g-干扰素抗病毒活性, 证实其中一株可中和重组马g-干扰素的抗病毒活性。结果表明: 杆状病毒表达的马g-干扰素具有较高的抗病毒活性, 其活性可被一株制备的抗重组马g-干扰素单克隆抗体抑制; 首次获得原核表达的具有抗病毒活性的马g-干扰素。     

The current situation and trend of tomato cultivation in China

Tomato (Lycopersicon esculentum Miller) is an important vegetable crop widely cultivated in China. According to the climate, four ecological districts of tomato cultivation can be distinguished, namely Southern District, Middle and Eastern District, Northern District, and Northeastern District. Tomatoes are grown mainly in plastic tunnels or in open fields. The varieties with large fruit, red or pink are favored. Though there are many diseases and pests which attack tomatoes, only a few of them were included in the breeding programme, such as TMV, CMV, Cladosperium fulvum, Pseudomonas solanacearum. Further work will include the disease resistance to other diseases and pests, fruit quality and long growing season for greenhouse production.     

CHD1L prevents lipopolysaccharide-induced hepatocellular carcinomar cell death by activating hnRNP A2/B1-nmMYLK axis

Chromodomain helicase/ATPase DNA-binding protein 1-like gene (CHD1L) has been characterized to be a driver gene in hepatocellular carcinoma (HCC). However, the intrinsic connections between CHD1L and intestinal dysbacteriosis-related inflammation reaction in HCC progression remain incompletely understood. In this study, a specific correlation between CHD1L and nonmuscle isoform of myosin light chain kinase (nmMLCK/nmMYLK), a newly identified molecule associated NF-κB signaling transduction, was disclosed in HCC. CHD1L promotes nmMYLK expression and prevents lipopolysaccharide (LPS) induced tumor cell death. In vitro experiment demonstrated that overexpressed nmMYLK is essential for CHD1L to maintain HCC cell alive, while knocking down nmMYLK significantly attenuate the oncogenic roles of CHD1L. Mechanism analysis revealed that nmMYLK can prevent Caspase-8 from combining with MyD88, an important linker of TLRs signaling pathway, while, knocking down nmMYLK facilitate the MyD88 combines with Caspase-8 and lead to the proteolytic cascade of Caspase as well as the consequent cell apoptosis. Mechanism analysis showed that CHD1L promotes the nmMYLK expression potentially through upregulating the heterogeneous nuclear ribonucleoproteins A2/B1 (hnRNP A2/B1) expression, which can bind to myosin light chain kinase (MYLK) pre-mRNA and lead to the regnant translation of nmMYLK. In summary, this work characterizes a previously unknown role of CHD1L in preventing LPS-induced tumor cell death through activating hnRNP A2/B1-nmMYLK axis. Further inhibition of CHD1L and its downstream signaling could be a novel promising strategy in HCC treatment.Subject terms: Cancer microenvironment, Apoptosis, Liver cancer     

利用甲壳素固定大肠杆菌（E.coli）细胞转化苯丙酮酸形成L—苯丙氨酸的研究

利用甲壳素作为固定化介质,能够保留83.3％的游离细胞转氨酶活性,以0.35mol/L苯丙酮酸为前体,于37℃下反应9小时,可产L-苯丙氨酸54.3g/L,其克分子转化率为94％。同时,用25％戊二醛溶液(30μl/g·cell)处理细胞1小时,再用0.3％OP溶液浸泡处理15小时,可以使固定化细胞转化率有较大的提高,Mg~(2+)对转化也有促进作用。     

Experimental and numerical study on the mechanical properties of cortical and spongy cranial bone of 8-week-old porcines at different strain rates

Biomechanics and Modeling in Mechanobiology - Pediatric porcines have widely been used as substitute for children in biomechanical research. Previous studies have used entire piglet cranium when...     

Primary High-Dose Murine Norovirus 1 Infection Fails To Protect from Secondary Challenge with Homologous Virus

Human noroviruses in the Caliciviridae family are the major cause of nonbacterial epidemic gastroenteritis worldwide. Primary human norovirus infection does not elicit lasting protective immunity, a fact that could greatly affect the efficacy of vaccination strategies. Little is known regarding the pathogenesis of human noroviruses or the immune responses that control them because there has previously been no small-animal model or cell culture system of infection. Using the only available small-animal model of norovirus infection, we found that primary high-dose murine norovirus 1 (MNV-1) infection fails to afford protection against a rechallenge with a homologous virus. Thus, MNV-1 represents a valuable model with which to dissect the pathophysiological basis for the lack of lasting protection against human norovirus infection. Interestingly, the magnitude of protection afforded by a primary MNV-1 infection inversely correlates with the inoculum dose. Future studies will elucidate the mechanisms by which noroviruses avoid the induction of protective immunity and the role played by the inoculum dose in this process, ultimately translating this knowledge into successful vaccination approaches.Human noroviruses (NVs) are estimated to be responsible for >95% of the nonbacterial epidemic gastroenteritis that occurs worldwide. The course of the disease is rapid, with symptoms including vomiting, diarrhea, and nausea arising approximately 24 h following infection and typically resolving 24 to 48 h later. NV outbreaks occur most commonly in semiclosed communities such as nursing homes, schools, hospitals, cruise ships, and military settings (11, 24, 31). Persons of all ages are susceptible to NV infection. Human NVs are thus associated with considerable morbidity and have a significant economic impact. Numerous human volunteer challenge studies have demonstrated that long-term immunity is not induced following primary NV infection of some volunteers (13, 20, 26). The pathophysiological basis for this lack of protection is unclear, since virus-specific adaptive immune responses are generated (1, 7, 9, 10). A similar lack of immunity has been observed in some individuals for a number of other viral pathogens that infect at mucosal surfaces, such as rhinoviruses (32) and respiratory syncytial virus (RSV) (16). Importantly, typical vaccination strategies have been unsuccessful at eliciting protective anti-RSV immunity and studies with animal models to understand the lack of immunity to either natural or vaccinating virus have been uninformative because protection is induced in animals (27). Extrapolating from RSV studies, it may be difficult to vaccinate against NVs and it will be important to understand the underlying cause in order to design more efficacious treatment regimens. Studies with a small-animal model recapitulating this atypical immune outcome would be extremely valuable.     

Accumulation of α-Keto Acids as Essential Components in Cyanide Assimilation by Pseudomonas fluorescens NCIMB 11764

Pyruvate (Pyr) and α-ketoglutarate (αKg) accumulated when cells of Pseudomonas fluorescens NCIMB 11764 were cultivated on growth-limiting amounts of ammonia or cyanide and were shown to be responsible for the nonenzymatic removal of cyanide from culture fluids as previously reported (J.-L. Chen and D. A. Kunz, FEMS Microbiol. Lett. 156:61–67, 1997). The accumulation of keto acids in the medium paralleled the increase in cyanide-removing activity, with maximal activity (760 μmol of cyanide removed min⁻¹ ml of culture fluid⁻¹) being recovered after 72 h of cultivation, at which time the keto acid concentration was 23 mM. The reaction products that formed between the biologically formed keto acids and cyanide were unambiguously identified as the corresponding cyanohydrins by ¹³C nuclear magnetic resonance spectroscopy. Both the Pyr and α-Kg cyanohydrins were further metabolized by cell extracts and served also as nitrogenous growth substrates. Radiotracer experiments showed that CO₂ (and NH₃) were formed as enzymatic conversion products, with the keto acid being regenerated as a coproduct. Evidence that the enzyme responsible for cyanohydrin conversion is cyanide oxygenase, which was shown previously to be required for cyanide utilization, is based on results showing that (i) conversion occurred only when extracts were induced for the enzyme, (ii) conversion was oxygen and reduced-pyridine nucleotide dependent, and (iii) a mutant strain defective in the enzyme was unable to grow when it was provided with the cyanohydrins as a growth substrate. Pyr and αKg were further shown to protect cells from cyanide poisoning, and excretion of the two was directly linked to utilization of cyanide as a growth substrate. The results provide the basis for a new mechanism of cyanide detoxification and assimilation in which keto acids play an essential role.Cyanide is a notorious poison. Its inhibitory effect on respiration has been known since the 1920s, when Warburg and Keilin first demonstrated that it combines with trivalent iron in cytochrome oxidase (38, 40, 44). Although highly toxic, it is a normal part of our environment for which mechanisms of biological formation (cyanogenesis) and detoxification exist (8, 22, 42). Cyanide also arises from various industrial practices such as steel coking, electroplating, and mining, but significant accumulations in the environment probably do not occur because of its highly reactive nature (13, 18, 41, 46). The interactions between microorganisms and cyanide, however, remain of interest, since the mechanisms of tolerance and assimilation are poorly understood. A number of reports documenting the ability of microorganisms to grow on cyanide have appeared, but the biochemical basis of these abilities has remained largely obscure. Most studies have reported its ability to serve as a nitrogen source only, since at the concentrations needed for it to serve as a carbon source, it is too toxic (15, 24). As far as is known, growth on cyanide requires that it be enzymatically converted to ammonia. Once formed it can then be readily incorporated into cellular macromolecules by established mechanisms (31). Two separate conversions have been described. They are hydrolytic and oxidative conversion, and they yield formic acid and carbon dioxide as reaction by-products, respectively. The enzyme responsible for hydrolytic conversion has variously been described as cyanidase, cyanide dihydratase, or cyanide nitrilase (CNN), and it catalyzes the reaction shown in equation 1. 1 Mechanistically, CNNs resemble other nitrilases (e.g., EC 3.5.5.1) that catalyze the direct conversion of organic nitriles into an organic acid and ammonia but for which the substrate range appears to be limited to cyanide. The involvement of CNNs in cyanide metabolism has been reported for Alcaligenes xylosooxidans subsp. denitrificans (19, 20), Bacillus pumilus (30), and Pseudomonas sp. (45). Oxidative conversion is mediated by an enzyme described as cyanide oxygenase (CNO). This enzyme has been described for Pseudomonas fluorescens NCIMB 11764 only (15, 23–26). Recent work in our laboratory has shown that CNO functions as a monooxygenase, since a single atom of molecular oxygen was shown to be incorporated during conversion (43). Since the other atom of oxygen in CO₂ was shown to be derived from water, a reaction mechanism in which cyanide undergoes initial monooxygenative attack to give an unknown intermediate (X-OH) as shown in equation 2 was proposed (43). 2 Further hydrolysis of X-OH is then expected to give CO₂ and NH₃ as shown in equation 3. 3 The nature of X-OH and whether an additional enzyme is required for its conversion are unknown. Interestingly, NCIMB 11764 also elaborates a CNN, but only CNO has been shown to be physiologically required for cyanide utilization (26). This conclusion was reached after it was found that mutants unable to grow on cyanide did not make CNO but could still elaborate CNN.CNO is induced when cyanide (KCN) is added to nitrogen-limited cells (4, 26). This approach for obtaining cells induced for the enzyme is more convenient than growing cells on cyanide, which requires several days of fed-batch cultivation. During the course of experiments aimed at optimizing CNO induction, we discovered that the consumption of cyanide and the appearance of CNO activity in cell extracts were not concomitant (3, 4). Further experiments showed that cyanide consumption independent of that catalyzed by CNO occurred nonenzymatically and that a reaction between cyanide and a metabolite excreted into the medium was responsible for cyanide’s removal (4). Since cyanide-removing activity in culture fluids consistently copurified with iron-chelating activity, it was concluded that the responsible metabolite was a siderophore, but further identification of this siderophore was not achieved. Here we report that the compounds responsible for nonenzymatic cyanide removal are α-keto acids, namely, pyruvate (Pyr) and α-ketoglutarate (αKg). These findings help explain the earlier reported involvement of a putative siderophore, since these compounds can act as iron chelators (10, 35). However, the additional ability to serve also as effective cyanide-scavenging agents has not generally been recognized. Both Pyr and αKg were excreted into the medium when P. fluorescens NCIMB 11764 was grown on nitrogen-limiting amounts of ammonia or cyanide as a nitrogen source, and we now demonstrate that these metabolites play an essential role in the utilization of cyanide as a growth substrate.     

The determination of physiological race of Fusarium oxysporum f. sp. lycopersici of tomato in Zhejiang, China

A group of differential tomato lines was used to identify the races of Fusarium oxysporum f. sp. lycopersici in Zhejiang, China. Marmande verte carries no resistant genes and Marporum carries gene I-1. Both lines Motelle and Mogeor have Gene I-1 and I-2. Tomato seedlings of eighteen days after sowing were inoculated with an isolate of Fusarium oxysporum f. sp. lycopersici, No. 98-2 and kept in a growth chamber. The seedlings were evaluated at fourteen days after inoculation. Results showed that Marmande verte and Marporum were severely infected by the pathogen and established as susceptible. Motelle and Mogeor were not infected and established as resistant. These results indicated that the isolate No. 98-2 represented the race 2 of Fusarium oxysporum f. sp. lycopersici and gene I-2 is necessary for obtaining resistance to this pathogen in the Zhejiang region.