Microbial aspartic proteases: current and potential applications in industry

Aspartic proteases are a relatively small group of proteolytic enzymes that are active in acidic environments and are found across all forms of life. Certain microorganisms secrete such proteases as virulence agents and/or in order to break down proteins thereby liberating assimilable sources of nitrogen. Some of the earlier applications of these proteolytic enzymes are found in the manufacturing of cheese where they are used as milk-clotting agents. Over the last decade, they have received tremendous research interest because of their involvement in human diseases. Furthermore, there has also been a growing interest on these enzymes for their applications in several other industries. Recent research suggests in particular that they could be used in the wine industry to prevent the formation of protein haze while preserving the wines’ organoleptic properties. In this mini-review, the properties and mechanisms of action of aspartic proteases are summarized. Thereafter, a brief overview of the industrial applications of this specific class of proteases is provided. The use of aspartic proteases as alternatives to clarifying agents in various beverage industries is mentioned, and the potential applications in the wine industry are thoroughly discussed.     

De novo genome assembly of Candida glabrata reveals cell wall protein complement and structure of dispersed tandem repeat arrays

Candida glabratais an opportunistic pathogen in humans, responsible for approximately 20% of disseminated candidiasis. Candida glabrata's ability to adhere to host tissue is mediated by GPI-anchored cell wall proteins (GPI-CWPs); the corresponding genes contain long tandem repeat regions. These repeat regions resulted in assembly errors in the reference genome. Here, we performed a de novo assembly of the C. glabrata type strain CBS138 using long single-molecule real-time reads, with short read sequences (Illumina) for refinement, and constructed telomere-to-telomere assemblies of all 13 chromosomes. Our assembly has excellent agreement overall with the current reference genome, but we made substantial corrections within tandem repeat regions. Specifically, we removed 62 genes of which 45 were scrambled due to misassembly in the reference. We annotated 31 novel ORFs of which 24 ORFs are GPI-CWPs. In addition, we corrected the tandem repeat structure of an additional 21 genes. Our corrections to the genome were substantial, with the length of new genes and tandem repeat corrections amounting to approximately 3.8% of the ORFeome length. As most corrections were within the coding regions of GPI-CWP genes, our genome assembly establishes a high-quality reference set of genes and repeat structures for the functional analysis of these cell surface proteins.     

A comparison of the nitrogen metabolic networks of Kluyveromyces marxianus and Saccharomyces cerevisiae

In grape must, nitrogen is available as a complex mixture of various compounds (ammonium and amino acids). Wine yeasts assimilate these multiple sources in order to suitably fulfil their anabolic requirements during alcoholic fermentation. Nevertheless, the order of uptake and the intracellular fate of these sources are likely to differ between strains and species. Using a two-pronged strategy of isotopic filiation and RNA sequencing, the metabolic network of nitrogen utilization and its regulation in Kluyveromyces marxianus were described, in comparison with those of Saccharomyces cerevisiae. The data highlighted differences in the assimilation of ammonium and arginine between the two species. The data also revealed that the metabolic fate of certain nitrogen sources differed, thereby resulting in the production of various amounts of key wine aroma compounds. These observations were corroborated by the gene expression analysis.     

Pharmacologic modulation of RNA splicing enhances anti-tumor immunity

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Vers une approche physiopathologique des troubles de l’éjaculation

Seminal emission and sperm expulsion are under the control of both the sympathetic and parasympathetic outflows and also of the somatic innervation conveyed by the pudendal nerve. The 2 phases of ejaculation are reflexive with the reflexes handled at the thoraco-lumbar and sacral levels of the spinal cord. Such a spinal organization remains widely unknown. The role of various peripheral neurotransmitters has been evidenced including norepinephrine and acetylcholine and also peptidergic, purinergic i.e. ATP and nitric oxide. Stimulation of the seminal tract afferents play a crucial in the onset of ejaculatory mechanisms. Except for the dorsal nerve of the penis, there is a lack of information concerning these afferents. Several supraspinal centers i.e. hypothalamus, medial amygdala, pons and nucleus paragigantocellularis exert descending and ascending inhibitory and excitatory influences on spinal nuclei controlling emission and expulsion of sperm. Central neurotransmission responsible for this supraspinal control could involve serotonin, oxytocin and norepinephrine. In the light of the available anatomical and neurophysiological data, pathophysiological aspects of ejaculatory disorders are futher discussed. Premature ejaculation could be related to a periheral and central hypersentivity. Most of the other ejaculation abnormalities are likely mainly related to an impairment of the central mechanisms.     

Assignment of the human CD9 gene to chromosome 12 (region P13) by use of human specific DNA probes

Summary We have used human specific DNA probes and somatic hybrid cell analysis to localize the human CD 9 gene to chromosome 12 (region p13).