Biochimie 

About: Biochimie is an academic journal published by Elsevier BV. The journal publishes majorly in the area(s): RNA & Medicine. It has an ISSN identifier of 0300-9084. Over the lifetime, 9482 publications have been published receiving 277587 citations.

Bacteriocins of lactic acid bacteria

Abstract: Lactic acid bacteria produce a variety of antagonistic factors that include metabolic end products, antibiotic-like substances and bactericidal proteins, termed bacteriocins. The range of inhibitory activity by bacteriocins of lactic acid bacteria can be either narrow, inhibiting only those strains that are closely related to the producer organism, or wide, inhibiting a diverse group of Gram-positive microorganisms. The following review will discuss biochemical and genetic aspects of bacteriocins that have been identified and characterized from lactic acid bacteria.

Toxic metal accumulation, responses to exposure and mechanisms of tolerance in plants

Abstract: Over the past 200 years emissions of toxic heavy metals have risen tremendously and significantly exceed those from natural sources for practically all metals. Uptake and accumulation by crop plants represents the main entry pathway for potentially health-threatening toxic metals into human and animal food. Of major concern are the metalloids arsenic (As) and selenium (Se), and the metals cadmium (Cd), mercury (Hg), and lead (Pb). This review discusses the molecular mechanisms of toxic metal accumulation in plants and algae, the responses to metal exposure, as well as our understanding of metal tolerance and its evolution. The main emphasis will be on cadmium, which is by far the most widely studied of the non-essential toxic metals/metalloids. Entry via Zn2+, Fe2+, and Ca2+ transporters is the molecular basis of Cd2+ uptake into plant cells. Much less is known about the partitioning of non-essential metals and about the genes underlying the enormous diversity among plants with respect to Cd accumulation in different tissues. Numerous studies have described symptoms and responses of plants upon toxic metal exposure. Mysterious are primary targets of toxicity, the degree of specificity of responses, the sensing and the signaling events that lead to transcriptional activation. All plants apparently possess a basal tolerance of toxic non-essential metals. For Cd and As, this is largely dependent on the phytochelatin pathway. Not understood is the molecular biology of Cd hypertolerance in certain plant species such as the metallophytes Arabidopsis halleri or Thlaspi caerulescens.

WWW-query: an on-line retrieval system for biological sequence banks.

Abstract: We have developed a World Wide Web (WWW) version of the sequence retrieval system Query: WWW-Query. This server allows to query nucleotide sequence banks in the EMBL/GenBank/DDBJ formats and protein sequence banks in the NBRF/PIR format. WWW-Query includes all the features of the on-line sequence browsers already available: possibility to build complex queries, integration of cross-references with different data banks, and access to the functional zones of biological interest. It also provides original services not available elsewhere: introduction of the notion of re-usable sequence lists, integration of dedicated helper applications for visualizing alignments and phylogenetic trees and links with multivariate methods for studying codon usage or for complementing phylogenies.

SREBP transcription factors: master regulators of lipid homeostasis.

Abstract: Sterol regulatory element binding proteins (SREBPs) are a family of transcription factors that regulate lipid homeostasis by controlling the expression of a range of enzymes required for endogenous cholesterol, fatty acid (FA), triacylglycerol and phospholipid synthesis. The three SREBP isoforms, SREBP-1a, SREBP-1c and SREBP-2, have different roles in lipid synthesis. In vivo studies using transgenic and knockout mice suggest that SREBP-1c is involved in FA synthesis and insulin induced glucose metabolism (particularly in lipogenesis), whereas SREBP-2 is relatively specific to cholesterol synthesis. The SREBP-1a isoform seems to be implicated in both pathways. SREBP transcription factors are synthetized as inactive precursors bound to the endoplasmic reticulum (ER) membranes. Upon activation, the precursor undergoes a sequential two-step cleavage process to release the NH(2)-terminal active domain in the nucleus (designated nSREBPs). SREBP processing is mainly controlled by cellular sterol content. When sterol levels decrease, the precursor is cleaved to activate cholesterogenic genes and maintain cholesterol homeostasis. This sterol-sensitive process appears to be a major point of regulation for the SREBP-1a and SREBP-2 isoforms but not for SREBP-1c. Moreover, the SREBP-1c isoform seems to be mainly regulated at the transcriptional level by insulin. The unique regulation and activation properties of each SREBP isoform facilitate the co-ordinate regulation of lipid metabolism; however, further studies are needed to understand the detailed regulation pathways that specifically regulate each SREBP isoform.

Fatty acid biosynthesis in microorganisms being used for Single Cell Oil production

Abstract: Single cell oils (SCOs) are now produced by various microorganisms as commercial sources of arachidonic acid (ARA) and docosahexaenoic acid (DHA). These oils are now used extensively as dietary supplements in infant formulas. An understanding of the underlying biochemistry and genetics of oil accumulation in such microorganisms is therefore essential if lipid yields are to be improved. Also an understanding of the biosynthetic pathways involved in the production of these polyunsaturated fatty acids (PUFAs) is also highly desirable as a prerequisite to increasing their content in the oils. An account is provided of the biosynthetic machinery that is necessary to achieve oil accumulation in an oleaginous species where it can account for lipid build up in excess of 70% of the cell biomass. Whilst PUFA production in most microorganisms uses a conventional fatty acid synthase (FAS) system followed by a series of desaturases and elongases, in Schizochytrium sp., and probably related thraustochytrid marine protists, PUFA synthesis now appears to be via a polyketide synthase (PKS) route. This route is discussed. It clearly represents a major departure from conventional fatty acid biosynthesis, possibly as a means of decreasing the amount of NADPH that is needed in the overall process.