Distribution of Tetrahydromethanopterin-Dependent Enzymes in Methylotrophic Bacteria and Phylogeny of Methenyl Tetrahydromethanopterin Cyclohydrolases

The methylotrophic proteobacterium Methylobacterium extorquens AM1 possesses tetrahydromethanopterin (H(4)MPT)-dependent enzymes, which are otherwise specific to methanogenic and sulfate-reducing archaea and which have been suggested to be involved in formaldehyde oxidation to CO(2) in M. extorquens AM1. The distribution of H(4)MPT-dependent enzyme activities in cell extracts of methylotrophic bacteria from 13 different genera are reported. H(4)MPT-dependent activities were detected in all of the methylotrophic and methanotrophic proteobacteria tested that assimilate formaldehyde by the serine or ribulose monophosphate pathway. H(4)MPT-dependent activities were also found in autotrophic Xanthobacter strains. However, no H(4)MPT-dependent enzyme activities could be detected in other autotrophic alpha-proteobacteria or in gram-positive methylotrophic bacteria. Genes encoding methenyl H(4)MPT cyclohydrolase (mch genes) were cloned and sequenced from several proteobacteria. Bacterial and archaeal Mch sequences have roughly 35% amino acid identity and form distinct groups in phylogenetic analysis.     

The promiscuity of heterospecific lox sites increases dramatically in the presence of palindromic DNA

Heterospecific lox sites are mutated lox sites that in the presence of Cre recombinase recombine with themselves but not or much less with wildtype loxP. We here show that in Escherichia coli both lox511 and lox2272 sites become highly promiscuous with respect to loxP when in the presence of Cre one of the recombination partners is present in a larger stretch of an inverted repeat of non-lox DNA. In such a palindromic DNA configuration, also the occurrence of other DNA repeat-mediated recombination events is somewhat increased in the presence of Cre. The results indicate that in recombinase mediated cassette exchange or other double lox applications based on the exclusivity of heterospecific lox sites, or in research combining Cre-lox approaches with hairpin RNA for gene silencing, the presence of duplicated DNA around lox sites has to be taken into account. It is proposed that the presence of palindromic non-lox DNA interferes with the homology search of the Cre enzyme prior to the actual recombination event.     

Climate and land use changes will degrade the configuration of the landscape for titi monkeys in eastern Brazil

Land use changes have profound effects on populations of Neotropical primates, and ongoing climate change is expected to aggravate this scenario. The titi monkeys from eastern Brazil (Callicebus personatus group) have been particularly affected by this process, with four of the five species now allocated to threatened conservation status categories. Here, we estimate the changes in the distribution of these titi monkeys caused by changes in both climate and land use. We also use demographic‐based, functional landscape metrics to assess the magnitude of the change in landscape conditions for the distribution predicted for each species. We built species distribution models (SDMs) based on maximum entropy for current and future conditions (2070), allowing for different global circulation models and contrasting scenarios of glasshouse gas concentrations. We refined the SDMs using a high‐resolution map of habitat remnants. We then calculated habitat availability and connectivity based on home‐range size and the dispersal limitations of the individual, in the context of a predicted loss of 10% of forest cover in the future. The landscape configuration is predicted to be degraded for all species, regardless of the climatic settings. This include reductions in the total cover of forest remnants, patch size and functional connectivity. As the landscape configuration should deteriorate severely in the future for all species, the prevention of further loss of populations will only be achieved through habitat restoration and reconnection to counteract the negative effects for these and several other co‐occurring species.     

Stop codon recognition in ciliates: Euplotes release factor does not respond to reassigned UGA codon

In eukaryotes, the polypeptide release factor 1 (eRF1) is involved in translation termination at all three stop codons. However, the mechanism for decoding stop codons remains unknown. A direct interaction of eRF1 with the stop codons has been postulated. Recent studies focus on eRF1 from ciliates in which some stop codons are reassigned to sense codons. Using an in vitro assay based on mammalian ribosomes, we show that eRF1 from the ciliate Euplotes aediculatus responds to UAA and UAG as stop codons and lacks the capacity to decipher the UGA codon, which encodes cysteine in this organism. This result strongly suggests that in ciliates with variant genetic codes eRF1 does not recognize the reassigned codons. Recent hypotheses describing stop codon discrimination by eRF1 are not fully consistent with the set of eRF1 sequences available so far and require direct experimental testing.     

Transduction of resistance to cyanide

Путем пассажей лизогенного штамма Escherichia coli K 12 на средах, содержавших повышающиеся кондентрадии дианистого калия, удалось вырастить варианты, резистентные к 0,4 мол. Кондент KCN. Полученные резистентые штаммы сохраняют свою резистентность и при пассажах на средах без дианистого калия. С приобретением устойчивости к дианистому калиию у этих штаммов изменились и другие свойства в сравнении с исходным штаммом. Некоторые изменения оказались обратимыми, другие, — как биохимические изменения, изменения чувствительности к ?агам и в продукции ?ага, — сохранялись стабильно и после 50 пассажей на средах без цианистого калия. С помощью ?ага, выделенного из штамма К 12, устойчивого к 0,4 мол. концентрации цианистого калия, удалась трансдукция не только устойчивости к цианистому калию, но одновременно и чувствительности к ?агам группы coli Т и утраты способности сбраживать дульцит. Однако связь между этими особенностями не была стопроцентной, так как перенесенная устойчивость к дианистому калию оказалась несколько более низкой, чем исходная (0,3 мол. Вместо 0,4 мол.), а бактерии после трансдукдии продуцировали не только ?аг α, как бактериидоноры, но и преимущественно первоначальный ?аг.     

Investigation of the mechanism of the action of dimethyllaurylbenzyl-ammonium chloride (ajatin) on rough and smooth forms of yeast cells

Ajatin эффект от потреблен ия кислорода в присутствии некото рых промежуточных и продукция была Гликолиз расследование вмест е с эффект iodoacetic кислоты, для того что бы пролить свет еще выше чувствительность грубый формы дрожжей для Ajatin и объяснить синергический дейст вия Ajatin и iodoacetic кислоты в присутстви и глюкозы. Было установлено, что окисление этанола и ацетата в грубой форме distiller дрожжи гораздо боле е чувствительны для действий Ajatin чем окисление глюкозы, в то время как в виде гладких разница в чувствительности ме жду этими двух процессов меньш е. Потребление кислорода в присутст вии этанола или ацетата в качестве субстрата значитель но сдерживается путем iodoacetic кислоты в виде гладких, но не зависит от этого ингибитора в грубой форме. На основе результато в и данных в литературе метаболизма гладких и грубые формы дрожже й обсуждается и Причины синергическ ий действия Ajatin и iodoacetic кислоты на потребление кислоро да в присутствии глюк озы принимаются вверх. Она представляет интерес для обнаружи ть, что окислительные проце ссы не мешает arsenite, относительно устойчив к Ajatin с тем, что в присутстви и arsenite разница в чувствительности дв ух формах дрожжей в действие по чти Ajatin исчезает.     

Catalytic antibodies in the bone marrow and other organs of Th mice during spontaneous development of experimental autoimmune encephalomyelitis associated with cell differentiation

Exact mechanisms of autoimmune disease development are still yet unknown. However, it is known that the development of autoimmune diseases is associated with defects in the immune system, namely, the violation of the bone marrow hematopoietic stem cells (HSCs) differentiation profiles. Different characteristics of autoimmune reaction development in experimental autoimmune encephalomyelitis (EAE) prone Th mice characterizing T-lymphocytes response were analyzed using standard approaches. Profiles of several HSCs differentiation of bone marrow (BFU-E, CFU-E, CFU-GM, CFU-GEMM, T- and B-lymphocytes) of Th male and female mice during spontaneous development of EAE were noticeably different. Patterns of total lymphocytes, B- and T-cells proliferation in several different organs (bone marrow, blood, spleen, thymus, and lymph nodes) were also remarkably different. In addition, there were in time noticeable differences in their changes for some organs of male and female mice. Characters of changes in the profiles of CD4 and CD8 cells proliferation in some organs not always coincide with those for total T lymphocytes. The changes in the differentiation profiles of HSCs and the level of lymphocytes proliferation in the bone marrow and other organs were associated with the increase in the concentration of antibodies against DNA, myelin basic protein, and myelin oligodendrocyte glycoprotein, and catalytic antibodies hydrolyzing these substrates. Despite some differences in changes in the analyzed parameters, in general, the spontaneous development of EAE in male and female mice occurs to some extent in a comparable way.

     

Lamin A as a Determinant of Mechanical Properties of the Cell Nucleus in Health and Disease

Biochemistry (Moscow) - One of the main factors associated with worse prognosis in oncology is metastasis, which is based on the ability of tumor cells to migrate from the primary source and to...     

Acute Treatment with Docosahexaenoic Acid Complexed to Albumin Reduces Injury after a Permanent Focal Cerebral Ischemia in Rats

Docosahexaenoic acid complexed to albumin (DHA-Alb) is highly neuroprotective after temporary middle cerebral artery occlusion (MCAo), but whether a similar effect occurs in permanent MCAo is unknown. Male Sprague-Dawley rats (270–330 g) underwent permanent MCAo. Neurological function was evaluated on days 1, 2 and 3 after MCAo. We studied six groups: DHA (5 mg/kg), Alb (0.63 or 1.25 g/kg), DHA-Alb (5 mg/kg+0.63 g/kg or 5 mg/kg+1.25 g/kg) or saline. Treatment was administered i.v. at 3 h after onset of stroke (n = 7–10 per group). Ex vivo imaging of brains and histopathology were conducted on day 3. Saline- and Alb-treated rats developed severe neurological deficits but were not significantly different from one another. In contrast, rats treated with low and moderate doses of DHA-Alb showed improved neurological score compared to corresponding Alb groups on days 2 and 3. Total, cortical and subcortical lesion volumes computed from T2 weighted images were reduced following a moderate dose of DHA-Alb (1.25 g/kg) by 25%, 22%, 34%, respectively, compared to the Alb group. The total corrected, cortical and subcortical infarct volumes were reduced by low (by 36–40%) and moderate doses (by 34–42%) of DHA-Alb treatment compared to the Alb groups. In conclusion, DHA-Alb therapy is highly neuroprotective in permanent MCAo in rats. This treatment can provide the basis for future therapeutics for patients suffering from ischemic stroke.