Cloning of the gene coding for chitobiase ofSerratia marcescens

Summary A λ phage DNA library ofSerratia marcescens was constructed and a clone carrying the gene coding for chitobiase (E.C.3.2.1.29) was isolated and characterized. Deletion analysis limited the cloned region to 4.5 kb that is capable of efficient expression of chitobiase.Escherichia coli cells harboring a plasmid carrying the cloned gene express chitobiase constitutively. The molecular weight of the protein is about 95000 daltons. In exponentially growingE. coli cells the chitobiase enzyme was found to be secreted into the periplasm.     

Conversion of human plasma high density lipoprotein-2 to high density lipoprotein-3. Roles of neutral lipid exchange and triglyceride lipases

Cholesterol esters accumulating in human plasma high density lipoproteins (HDL) are important in conversion of HDL3 to larger HDL2. We studied whether mechanisms of removal of cholesterol esters from HDL might be important in a reverse direction, i.e. conversion of HDL2 to HDL3. Native HDL2 or HDL3 is incubated with very low density lipoproteins (VLDL) and lipoprotein-poor plasma (d greater than 1.21 g/ml) at 37 degrees C. After incubation, "modified" (M) VLDL, and HDL2 or HDL3 are reisolated by ultracentrifugation. In modified M-HDL2 or M-HDL3, triglyceride becomes the major core lipid as the triglyceride/cholesterol ester weight ratio increases 8-10-fold relative to native HDL. With only small changes in protein/phospholipid ratios in M-HDLs, the large decrease in cholesterol ester/protein ratios suggest net cholesterol ester loss from HDL. Quantitative recovery analyses prove that the cholesterol esters lost from HDL are transferred to M-VLDL, which is now richer in cholesterol ester and poorer in triglyceride. These substantial exchanges of HDL lipids are not associated by significant transfer of HDL apoproteins but are dependent on neutral lipid transfer factors present in human lipoprotein-poor plasma (d greater than 1.21 g/ml). Similar results are obtained when purified core lipid transfer protein replaces d greater than 1.21 g/ml plasma in these incubations. After depletion of cholesterol ester from HDL, most but not all, exchanged triglyceride can be removed by lipolysis with either hepatic or lipoprotein lipase, resulting in a post-lipolysis HDL2 with an increased triglyceride content relative to normal HDL. With successive incubations with VLDL, and core lipid transfer factors, HDL2 loses more than two-thirds of its cholesterol esters. After lipolysis of acquired triglyceride, HDL2 is remodeled, in both composition and flotation parameters, toward HDL3.     

Sequence of gonadal events and oestradiol levels in Sparus aurata (L.) under two photoperiod regimes

Individually tagged Sparus aurata were kept in tanks with running sea water (21°± 2°C) during their second and third years of life. Gonads were biopsied and blood was sampled at monthly intervals. Thirteen of 50 fish in the second year and 24 of 35 fish in the third year were phenotypically females. Fish kept under 16L/8D photoperiod from July 1981 to August 1982 did not reach maturation; waves of initial ovarian growth alternated with waves of atresia. When photoperiod was shortened as from August 1982, gonadal development commenced within a month and proceeded at a rate higher than that of the control fish reared under natural photoperiod. Under natural photoperiod oestradiol serum levels (E₂) were relatively low during the resting phase, May-October (108 ± 11 pg ml⁻¹), and during the late vitellogenic phase (502 ± 76 pg ml⁻¹). High levels (1669 ± 312 and 1240 ± 172pg ml⁻¹) occurred during the early vitellogenic and the maturational phases. The high level of E₂ during the spawning season of S. aurata is explained by earlier reports indicating a prolonged breeding season with daily release of eggs, and alternating daily surges of E₂ and 17α, 20β, dihydroxy-4-pregnen-3-one, possibly a 'maturational progestin' in this fish. In phenotypic males, E₂ was highest during early spermatogenic phases (745 ± 142pg ml⁻¹) but was low (155 ± 11 pg ml⁻¹) in males with running sperm.     

The 5′ untranslated region of Arabidopsis thaliana calmodulin cDNA is an independent cDNA containing an open reading frame

A cDNA clone, pAUK1, with an open reading frame (ORF) coding for a hypothetical 164-amino-acid protein was isolated from an Arabidopsis thaliana (L.) Heynh cDNA library. The clone was attached, tail to tail, to the 3′ end of A. thaliana hexokinase cDNA. An almost identical sequence had been previously described as the 5′ untranslated region (5′ UTR) of A. thaliana calmodulin cDNA (ACaM-2). Sequence comparison with three additional A. thaliana truncated cDNA clones which appear in a database (GenBank) supports the conclusion that pAUKl is identical to the 5′ UTR of ACaM-2 and that the 5′ UTR of ACaM-2 is an independent cDNA artificially linked to A. thaliana calmodulin cDNA.     

Use of a Novel Probiotic Formulation to Alleviate Lactose Intolerance Symptoms—a Pilot Study

Probiotics and Antimicrobial Proteins - Lactose intolerance is a common condition caused by lactase deficiency and may result in symptoms of lactose malabsorption (bloating, flatulence, abdominal...     

Ethnic groups and high sensitivity C-reactive protein in Israel

Abstract

High-sensitivity C-reactive protein (hs-CRP) is a biomarker that correlates with atherothrombotic risk and outcome. hs-CRP is influenced by various modifiable and non-modifiable factors. We studied the relationship between ethnic background and hs-CRP level, among the Jewish population in Israel. A total of 3659 men and 2180 women were divided into two ethnic groups (Ashkenazi and Sephardic Jews), based on the knowledge of Jewish immigration patterns throughout the centuries. Mean hs-CRP levels were calculated for each group and were adjusted for various factors known to influence hs-CRP. Sephardic Jews were found to have higher adjusted mean hs-CRP levels (2.0 mg l^?1 for men and 3.9 mg l^?1 for women) compared with Ashkenazi Jews (1.5 mg l^?1 for men and 2.9 mg l^?1 for women). Ethnic background emerged as an independent significant predictor of hs-CRP levels. We demonstrated that ethnicity is an important factor when considering hs-CRP as a marker of atherothrombotic risk.     

Plant functional traits and community assembly along interacting gradients of productivity and fragmentation

Quantifying the association of plant functional traits to environmental gradients is a promising approach for understanding and projecting community responses to land use and climatic changes. Although habitat fragmentation and climate are expected to affect plant communities interactively, there is a lack of empirical studies addressing trait associations to fragmentation in different climatic regimes.In this study, we analyse data on the key functional traits: specific leaf area (SLA), plant height, seed mass and seed number. First, we assess the evidence for the community assembly mechanisms habitat filtering and competition at different spatial scales, using several null-models and a comprehensive set of community-level trait convergence and divergence indices. Second, we analyse the association of community-mean traits with patch area and connectivity along a south–north productivity gradient.We found clear evidence for trait convergence due to habitat filtering. In contrast, the evidence for trait divergence due to competition fundamentally depended on the null-model used. When the null-model controlled for habitat filtering, there was only evidence for trait divergence at the smallest sampling scale (0.25 m × 0.25 m). All traits varied significantly along the S–N productivity gradient. While plant height and SLA were consistently associated with fragmentation, the association of seed mass and seed number with fragmentation changed along the S–N gradient.Our findings indicate trait convergence due to drought stress in the arid sites and due to higher productivity in the mesic sites. The association of plant traits to fragmentation is likely driven by increased colonization ability in small and/or isolated patches (plant height, seed number) or increased persistence ability in isolated patches (seed mass).Our study provides the first empirical test of trait associations with fragmentation along a productivity gradient. We conclude that it is crucial to study the interactive effects of different ecological drivers on plant functional traits.     

The Effect of Chemical Chaperones on the Assembly and Stability of HIV-1 Capsid Protein

Chemical chaperones are small organic molecules which accumulate in a broad range of organisms in various tissues under different stress conditions and assist in the maintenance of a correct proteostasis under denaturating environments. The effect of chemical chaperones on protein folding and aggregation has been extensively studied and is generally considered to be mediated through non-specific interactions. However, the precise mechanism of action remains elusive. Protein self-assembly is a key event in both native and pathological states, ranging from microtubules and actin filaments formation to toxic amyloids appearance in degenerative disorders, such as Alzheimer''s and Parkinson''s diseases. Another pathological event, in which protein assembly cascade is a fundamental process, is the formation of virus particles. In the late stage of the virus life cycle, capsid proteins self-assemble into highly-ordered cores, which encapsulate the viral genome, consequently protect genome integrity and mediate infectivity. In this study, we examined the effect of different groups of chemical chaperones on viral capsid assembly in vitro, focusing on HIV-1 capsid protein as a system model. We found that while polyols and sugars markedly inhibited capsid assembly, methylamines dramatically enhanced the assembly rate. Moreover, chemical chaperones that inhibited capsid core formation, also stabilized capsid structure under thermal denaturation. Correspondingly, trimethylamine N-oxide, which facilitated formation of high-order assemblies, clearly destabilized capsid structure under similar conditions. In contrast to the prevailing hypothesis suggesting that chemical chaperones affect proteins through preferential exclusion, the observed dual effects imply that different chaperones modify capsid assembly and stability through different mechanisms. Furthermore, our results indicate a correlation between the folding state of capsid to its tendency to assemble into highly-ordered structures.