Efficient homolactic fermentation by Kluyveromyces lactis strains defective in pyruvate utilization and transformed with heterologous LDH gene

A high yield of lactic acid per gram of glucose consumed and the absence of additional metabolites in the fermentation broth are two important goals of lactic acid production by microrganisms. Both purposes have been previously approached by using a Kluyveromyces lactis yeast strain lacking the single pyruvate decarboxylase gene (KlPDC1) and transformed with the heterologous lactate dehydrogenase gene (LDH). The LDH gene was placed under the control the KlPDC1 promoter, which has allowed very high levels of lactate dehydrogenase (LDH) activity, due to the absence of autoregulation by KlPdc1p. The maximal yield obtained was 0.58 g/g, suggesting that a large fraction of the glucose consumed was not converted into pyruvate. In a different attempt to redirect pyruvate flux toward homolactic fermentation, we used K. lactis LDH transformant strains deleted of the pyruvate dehydrogenase (PDH) E1alpha subunit gene. A great process improvement was obtained by the use of producing strains lacking both PDH and pyruvate decarboxylase activities, which showed yield levels of as high as 0.85 g/g (maximum theoretical yield, 1 g/g), and with high LDH activity

The 'petite negative' yeast Kluyveromyces lactis has a single gene expressing pyruvate decarboxylase activity

We cloned and sequenced the pyruvate decarboxylase (PDC; EC 4.1.1.1) structural gene KlPDCA in the yeast Kluyveromyces lactis and found it to be allelic to the previously isolated rag6 mutation. The putative amino acid sequence of the KlPdcAp appeared to be highly homologous to those of the yeast Pdc proteins identified so far. The disruption of KIPDCA indicated that it is the only PDC structural gene in K. lactis, as evidenced by the lack of PDC activity and ethanol production in the pdcAdelta strains and by the absence of growth on glucose in the presence of respiratory inhibitors. It was observed that expression of the KlPDCA gene is induced by glucose at the transcriptional level. Transcription of the gene was reduced in the ragl, rag2, rag5 and rag8 mutants, which are defective for the low-affinity glucose permease, phosphoglucose isomerase, hexokinase, and a positive regulator of RAG1 expression, respectively

Virtual reality implementation as a useful software tool for e-health applications

Human hand and finger movements are of obvious importance. The possibility of recording all fingers joints movements during everyday life is then strategic for medical diagnosis, surgery and post traumatic rehabilitation. A proper presentation of recorded data can be really useful for doctors and therapists to correctly act in the occurrence of peripheral nerve injury, rigidities, camptodactyly (decline in permanent deformity of the interphalangeal junction), orthoses, tenolisi, congenital malformations, trauma, dexterity and/or muscular and/or articulate motility evaluations, thumb atros, syndromes, use of mentors, spasm, use of mechanical supports etc.. According to this context we report a virtual reality implementation on the basis of fingers movements recorded data, suitable for fingers joints movement analysi

CTLA-4–Ig Activates Forkhead Transcription Factors and Protects Dendritic Cells from Oxidative Stress in Nonobese Diabetic Mice

Prediabetes and diabetes in nonobese diabetic (NOD) mice have been targeted by a variety of immunotherapies, including the use of a soluble form of cytotoxic T lymphocyte antigen 4 (CTLA-4) and interferon (IFN)-γ. The cytokine, however, fails to activate tolerogenic properties in dendritic cells (DCs) from highly susceptible female mice early in prediabetes. The defect is characterized by impaired induction of immunosuppressive tryptophan catabolism, is related to transient blockade of the signal transducer and activator of transcription (STAT)1 pathway of intracellular signaling by IFN-γ, and is caused by peroxynitrite production. Here, we show that soluble CTLA-4 imparts suppressive properties to DCs from early prediabetic NOD female mice through mechanisms that rely on autocrine signaling by IFN-γ. Although phosphorylation of STAT1 in response to IFN-γ is compromised in those mice, CTLA-4 obviates the defect. IFN-γ–driven expression of tryptophan catabolism by CTLA-4–immunoglobulin is made possible through the concomitant activation of the Forkhead Box class O (FOXO) transcription factor FOXO3a, induction of the superoxide dismutase gene, and prevention of peroxynitrite formation