Amazonian Amerindians exhibit high variability of KIR profiles

Natural killer cell immunoglobulin-like receptors (KIRs) mediate cell lysis through the recognition of human leukocyte antigen class I complexes in target cells, playing an important role in innate immune response. In this context, disease-based selective pressures could be relevant, leaving signatures detected by population studies. However, most population studies on KIR variability have focused on Europe and Asia, while Americas, Oceania, and Africa remain poorly studied. The aim of this study was to analyze the variability of KIR genes in Amerindian tribes from the Amazon region to infer about their evolutionary history. KIR profiles were estimated in 40 individuals from six Amazonian Amerindian tribes using single specific primer polymerase chain reaction. Twenty-five different profiles were identified, and surprisingly, the haplogroup A frequency was the lowest observed in human populations (16%). Results showed also that KIR variability was higher in this group in contrast to Venezuelan Amerindians. Principal components analysis evidenced that Amerindians formed a separated group from other worldwide populations and showed a higher intraethnic differentiation in comparison to other ethnic groups. Such pattern may reflect small effective size and intense genetic drift. However, because of the role of KIR in immune response, selective pressures cannot be entirely ruled out.     

Mutation in TECPR2 Reveals a Role for Autophagy in Hereditary Spastic Paraparesis

We studied five individuals from three Jewish Bukharian families affected by an apparently autosomal-recessive form of hereditary spastic paraparesis accompanied by severe intellectual disability, fluctuating central hypoventilation, gastresophageal reflux disease, wake apnea, areflexia, and unique dysmorphic features. Exome sequencing identified one homozygous variant shared among all affected individuals and absent in controls: a 1 bp frameshift TECPR2 deletion leading to a premature stop codon and predicting significant degradation of the protein. TECPR2 has been reported as a positive regulator of autophagy. We thus examined the autophagy-related fate of two key autophagic proteins, SQSTM1 (p62) and MAP1LC3B (LC3), in skin fibroblasts of an affected individual, as compared to a healthy control, and found that both protein levels were decreased and that there was a more pronounced decrease in the lipidated form of LC3 (LC3II). siRNA knockdown of TECPR2 showed similar changes, consistent with aberrant autophagy. Our results are strengthened by the fact that autophagy dysfunction has been implicated in a number of other neurodegenerative diseases. The discovered TECPR2 mutation implicates autophagy, a central intracellular mechanism, in spastic paraparesis.     

A novel bacterial symbiont in the nematode Spirocerca lupi

ABSTRACT: BACKGROUND: The parasitic nematode Spirocerca lupi (Spirurida: Thelaziidae), the canine esophagealworm, is the causative agent of spirocercosis, a disease causing morbidity and mortality indogs. Spirocerca lupi has a complex life cycle, involving an obligatory coleopteranintermediate host (vector), an optional paratenic host, and a definitive canid host. Thediagnosis of spirocercosis is challenging, especially in the early disease stages, when adultworms and clinical signs are absent. Thus, alternative approaches are needed to promote earlydiagnosis. The interaction between nematodes and their bacterial symbionts has recentlybecome a focus of novel treatment regimens for other helminthic diseases. RESULTS: Using 16S rDNA-based molecular methods, here we found a novel bacterial symbiont in S.lupi that is closely related to Comamonas species (Brukholderiales: Comamonadaceae) of thebeta-proteobacteria. Its DNA was detected in eggs, larvae and adult stages of S. lupi. Usingfluorescent in situ hybridization technique, we localized Comamonas sp. to the gut epithelialcells of the nematode larvae. Specific PCR enabled the detection of this symbiont's DNA inblood obtained from dogs diagnosed with spirocercosis. CONCLUSIONS: The discovery of a new Comamonas sp. in S. lupi increase the complexity of the interactionsamong the organisms involved in this system, and may open innovative approaches fordiagnosis and control of spirocercosis in dogs.     

MHO1, an evolutionarily conserved gene, is synthetic lethal with PLC1; Mho1p has a role in invasive growth

The novel protein Memo (Mediator of ErbB2 driven cell motility) was identified in a screen for ErbB2 interacting proteins and found to have an essential function in cell motility. Memo is evolutionarily conserved with homologs found in all branches of life; the human and yeast proteins have a similarity of >50%. In the present study we used the model organism S. cerevisiae to characterize the Memo-homologue Mho1 (Yjr008wp) and to investigate its function in yeast. In a synthetic lethal screen we found MHO1 as a novel synthetic lethal partner of PLC1, which encodes the single phospholipase C in yeast. Double-deleted cells lacking MHO1 and PLC1, proliferate for up to ten generations. Introduction of human Memo into the memoΔplc1Δ strain rescued the synthetic lethal phenotype suggesting that yeast and human proteins have similar functions. Mho1 is present in the cytoplasm and the nucleus of yeast cells; the same distribution of Memo was found in mammalian cells. None of the Memo homologues have a characteristic nuclear localization sequence, however, a conserved nuclear export sequence is found in all. In mammalian cells, blocking nuclear export with Leptomycin B led to nuclear Memo accumulation, suggesting that it is actively exported from the nucleus. In yeast MHO1 expression is induced by stress conditions. Since invasive growth in S. cerevisiea is also stress-induced, we tested Mho1's role in this response. MHO1 deletion had no effect on invasion induced by nutrient deprivation, however, Mho1 overexpression blocked the invasive ability of yeast cells, suggesting that Mho1 might be acting in a dominant negative manner. Taken together, our results show that MHO1 is a novel synthetic lethal interactor with PLC1, and that both gene products are required for proliferation. Moreover, a role for Memo in cell motility/invasion appears to be conserved across species.     

Purification of a cysteine proteinase from Carica candamarcensis L. and cloning of a genomic putative fragment coding for this enzyme.

We describe the purification of a cysteine proteinase from latex of Carica candamarcensis, hereby designated CC23. The enzyme has been purified by ion-exchange chromatography and behaves electrophoretically as a monomer of M(r) 23,000 and optimal pH of 8.0. It displays a basic isoelectric point, has one cysteine residue in the active site by titration with E-64, confirmed by DNA sequencing, and responds to proteinase inhibitors as a classic cysteine proteinase. The K(m) and k(cat)/K(m) for CC23 using BAPNA were respectively 14.7 +/- 1.8 x 10(-4) M and 1.3 x 10(3) M(-1) s(-1). Therefore, the catalytic efficiency of CC23 is sixfold higher than that of CC-I, another proteinase from the same plant. DNA primers were designed to amplify by PCR a genomic sequence related to this enzyme. An 895-bp DNA fragment was cloned and sequenced. It shows strong homology with chymopapain isoform IV from C. papaya. The translated sequence is similar to that of chymopapain isoform II (73%) and CC-III (77%) from C. candamarcensis.     

Active metabolites produced by Penicillium chrysogenum IFL1 growing on agro-industrial residues

Microbial extracts continue to be a productive source of new molecules with biotechnological importance. Fungi of the genus Penicillium are known to produce biologically active secondary metabolites. The goal of this work is verify the production of antimicrobial metabolites by Penicillium chrysogenum IFL1 using agro-industrial residues. P. chrysogenum IFL1 produced active metabolites growing on the agro-industrial residues, grape waste and cheese whey. The 7-day cultures showed antimicrobial activities against bacteria, fungi and amoebae. The filtrate of the cheese whey culture inhibited the growth of the bacteria Staphylococcus aureus, Bacillus cereus and Pseudomonas aeruginosa, the fungus Fusarium oxysporum and the amoeba Acanthamoeba polyphaga. Due to the greater antimicrobial activity of the cheese whey culture, a footprinting profile was carried out using the ESI-MS and ESI-MS/MS techniques. The presence of penicillin G and other metabolites that have antimicrobial activity such as penicillin V and rugulosin can be suggested. P. chrysogenum IFL1 was able to produce a wide variety of antimicrobial compounds on agro-industrial residues, which makes the process ecologically friendly.     

Bud proliferation and plant regeneration in liquid-cultured philodendron treated with ancymidol and paclobutrazol

Philodendron plants propagated in liquid shake or bioreactor cultures proliferated profusely in the presence of paclobutrazol (PAC) and to a lesser extent in the presence of ancymidol (ANC). The growth retardants inhibited leaf development and induced the formation of bud clusters. Short transient treatments with low concentrations (1.7–3.4 μM) of the growth retardants limited leaf growth and proliferation to a lesser extent than higher concentrations (6.8–17 μM). The growth retardants had a carryover dwarfing effect in the semi-solid hardening medium, which was more pronounced at the higher concentrations or prolonged exposure periods. Regenerated plants resumed normal growth 3–6 weeks after transplanting. Treatment with growth retardants may become a useful method in the prevention of abnormal leaf growth in large-scale liquid cultures, as well as in enhancing bud proliferation.