The Iranian vole Microtus irani occurs in Lebanon (Mammalia: Rodentia)

We studied 1140 bp cytochrome b sequences of social voles from three localities in Lebanon. The results were compared with published sequences representing seven species of social voles. New sequences from Lebanon clustered with reference samples of two species: M. guentheri and M. irani. While M. guentheri was already reported for Lebanon, M. irani is a new addition to the fauna of Lebanon, and the third known record for the species. Animals were collected in two localities above Tripolis at 855 m and 1430 m a.s.l., respectively.     

Insights from modeling studies on how climate change affects invasive alien species geography

Climate change and biological invasions are threatening biodiversity and ecosystem services worldwide. It has now been widely acknowledged that climate change will affect biological invasions. A large number of studies have investigated predicted shifts and other changes in the geographic ranges of invasive alien species related to climate change using modeling approaches. Yet these studies have provided contradictory evidence, and no consensus has been reached. We conducted a systematic review of 423 modeling case studies included in 71 publications that have examined the predicted effects of climate change on those species. We differentiate the approaches used in these studies and synthesize their main results. Our results reaffirm the major role of climate change as a driver of invasive alien species distribution in the future. We found biases in the literature both regarding the taxa, toward plants and invertebrates, and the areas of the planet investigated. Despite these biases, we found for the plants and vertebrates studied that climate change will more frequently contribute to a decrease in species range size than an increase in the overall area occupied. This is largely due to oceans preventing terrestrial invaders from spreading poleward. In contrast, we found that the ranges of invertebrates and pathogens studied are more likely to increase following climate change. An important caveat to these findings is that researchers have rarely considered the effects of climate change on transport, introduction success, or the resulting impacts. We recommend closing these research gaps, and propose additional avenues for future investigations, as well as opportunities and challenges for managing invasions under climate change.     

Dystrophin predominantly localizes to the transverse tubule/Z-line regions of single ventricular myocytes and exhibits distinct associations with the membrane

Dystrophin is a high molecular weight protein present at low abundance in skeletal, cardiac and smooth muscle and in trace amounts in brain. In skeletal muscle, dystrophin is uniformly distributed along the inner surface of the plasma membrane. Biochemical fractionation studies have shown that all detectable skeletal muscle dystrophin is tightly associated with a complex of wheat germ agglutinin (WGA)-binding and concanavalin A (Con A) binding sarcolemmal glycoproteins. Absence of dystrophin is the primary biochemical defect in patients with Duchenne muscular dystrophy and leads to segmental necrosis of their skeletal myofibers. Although present in similar amounts in normal cardiac and skeletal muscle, the absence of dystrophin from cardiac muscle has less severe effects on the survival of cardiac cells. We have therefore examined whether there are differences in the properties of cardiac and skeletal dystrophin. We report that in contrast to skeletal muscle, cardiac dystrophin is distributed between distinct pools: a soluble cytoplasmic pool, a membrane-bound pool not associated with WGA-binding glycoproteins and a membrane-bound pool associated with WGA-binding glycoproteins. Cardiac dystrophin was not associated with any Con A binding glycoproteins. Immunohistochemical localization studies in isolated ventricular myocytes reveal a distinct punctate staining pattern for dystrophin, approximating to the level of the transverse tubule/Z-line and contrasting with the uniform sarcolemmal staining reported for skeletal muscle fibers. The distinct properties of cardiac dystrophin suggest unique roles for this protein in cardiac versus skeletal muscle function.Abbreviations Dys Dystrophin - T-tubule Transverse tubule - SDS-PAGE Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis - WGA Wheat Germ Agglutinin - Con A Concanavalin A - DHP Dihydropyridine receptor - FITC Fluorescein Isothiocyanate Conjugate - NAG N-Acetyl-D-Glucosamine - NP-40 NONIDET P-40 - PBS Phosphate-Buffered Saline - TBST Tris Buffered Saline-Tween     

Mitochondrial quality control: Cell-type-dependent responses to pathological mutant mitochondrial DNA

Pathological mutations in the mitochondrial DNA (mtDNA) produce a diverse range of tissue-specific diseases and the proportion of mutant mitochondrial DNA can increase or decrease with time via segregation, dependent on the cell or tissue type. Previously we found that adenocarcinoma (A549.B2) cells favored wild-type (WT) mtDNA, whereas rhabdomyosarcoma (RD.Myo) cells favored mutant (m3243G) mtDNA. Mitochondrial quality control (mtQC) can purge the cells of dysfunctional mitochondria via mitochondrial dynamics and mitophagy and appears to offer the perfect solution to the human diseases caused by mutant mtDNA. In A549.B2 and RD.Myo cybrids, with various mutant mtDNA levels, mtQC was explored together with macroautophagy/autophagy and bioenergetic profile. The 2 types of tumor-derived cell lines differed in bioenergetic profile and mitophagy, but not in autophagy. A549.B2 cybrids displayed upregulation of mitophagy, increased mtDNA removal, mitochondrial fragmentation and mitochondrial depolarization on incubation with oligomycin, parameters that correlated with mutant load. Conversely, heteroplasmic RD.Myo lines had lower mitophagic markers that negatively correlated with mutant load, combined with a fully polarized and highly fused mitochondrial network. These findings indicate that pathological mutant mitochondrial DNA can modulate mitochondrial dynamics and mitophagy in a cell-type dependent manner and thereby offer an explanation for the persistence and accumulation of deleterious variants.     

Rock glaciers in crystalline catchments: Hidden permafrost‐related threats to alpine headwater lakes

A global warming‐induced transition from glacial to periglacial processes has been identified in mountainous regions around the world. Degrading permafrost in pristine periglacial environments can produce acid rock drainage (ARD) and cause severe ecological damage in areas underlain by sulfide‐bearing bedrock. Limnological and paleolimnological approaches were used to assess and compare ARDs generated by rock glaciers, a typical landform of the mountain permafrost domain, and their effects on alpine headwater lakes with similar morphometric features and underlying bedrock geology, but characterized by different intensities of frost action in their catchments during the year. We argue that ARD and its effects on lakes are more severe in the alpine periglacial belt with mean annual air temperatures (MAAT) between ?2°C and +3°C, where groundwater persists in the liquid phase for most of the year, in contrast to ARD in the periglacial belt where frost action dominates (MAAT < ?2°C). The findings clearly suggest that the ambient air temperature is an important factor affecting the ARD production in alpine periglacial environments. Applying the paleoecological analysis of morphological abnormalities in chironomids through the past millennium, we tested and rejected the hypothesis that unfavorable conditions for aquatic life in the ARD‐stressed lakes are largely related to the temperature increase over recent decades, responsible for the enhanced release of ARD contaminants. Our results indicate that the ARDs generated in the catchments are of a long‐lasting nature and the frequency of chironomid morphological deformities was significantly higher during the Little Ice Age (LIA) than during pre‐ or post‐LIA periods, suggesting that lower water temperatures may increase the adverse impacts of ARD on aquatic invertebrates. This highlights that temperature‐mediated modulations of the metabolism and life cycle of aquatic organisms should be considered when reconstructing long‐term trends in the ecotoxicological state of lakes.     

Co-purification of soluble human galactosyltransferase and immunoglobulins

Preparations of human malignant effusion galactosyltransferase activity purified according to previously published techniques using enzyme-specific affinity chromatography consistently produced antibodies directed toward immunoglobulins with no detectable antigalactosyltransferase. Double immunodiffusion analysis of the antigen showed the presence of both IgG and IgA. Affinity chromatography with anti-human IgG-Sepharose and anti-human serum-Sepharose resulted in a 48,000-fold purification of galactosyltransferase activity with no detectable IgG by radioimmunoassay. Immunization of rabbits with this preparation produced antibodies directed against galactosyltransferase activity and minimal anti-Ig. The persistence of immunoglobulins during the purification of soluble galactosyltransferase activity through two enzyme-specific affinity chromatographic steps suggests an association of immunoglobulins with galactosyltransferase activity.     

Complete mitochondrial DNA analysis of eastern Eurasian haplogroups rarely found in populations of northern Asia and eastern Europe

With the aim of uncovering all of the most basal variation in the northern Asian mitochondrial DNA (mtDNA) haplogroups, we have analyzed mtDNA control region and coding region sequence variation in 98 Altaian Kazakhs from southern Siberia and 149 Barghuts from Inner Mongolia, China. Both populations exhibit the prevalence of eastern Eurasian lineages accounting for 91.9% in Barghuts and 60.2% in Altaian Kazakhs. The strong affinity of Altaian Kazakhs and populations of northern and central Asia has been revealed, reflecting both influences of central Asian inhabitants and essential genetic interaction with the Altai region indigenous populations. Statistical analyses data demonstrate a close positioning of all Mongolic-speaking populations (Mongolians, Buryats, Khamnigans, Kalmyks as well as Barghuts studied here) and Turkic-speaking Sojots, thus suggesting their origin from a common maternal ancestral gene pool. In order to achieve a thorough coverage of DNA lineages revealed in the northern Asian matrilineal gene pool, we have completely sequenced the mtDNA of 55 samples representing haplogroups R11b, B4, B5, F2, M9, M10, M11, M13, N9a and R9c1, which were pinpointed from a massive collection (over 5000 individuals) of northern and eastern Asian, as well as European control region mtDNA sequences. Applying the newly updated mtDNA tree to the previously reported northern Asian and eastern Asian mtDNA data sets has resolved the status of the poorly classified mtDNA types and allowed us to obtain the coalescence age estimates of the nodes of interest using different calibrated rates. Our findings confirm our previous conclusion that northern Asian maternal gene pool consists of predominantly post-LGM components of eastern Asian ancestry, though some genetic lineages may have a pre-LGM/LGM origin.     

Inducer exclusion by glucose 6-phosphate in Escherichia coli

The main mechanism causing catabolite repression by glucose and other carbon sources transported by the phosphotransferase system (PTS) in Escherichia coli involves dephosphorylation of enzyme IIA^Glc as a result of transport and phosphorylation of PTS carbohydrates. Dephosphorylation of enzyme IIA^Glc leads to 'inducer exclusion': inhibition of transport of a number of non-PTS carbon sources (e.g. lactose, glycerol), and reduced adenylate cyclase activity. In this paper, we show that the non-PTS carbon source glucose 6-phosphate can also cause inducer exclusion. Glucose 6-phosphate was shown to cause inhibition of transport of lactose and the non-metabolizable lactose analogue methyl-β- D -thiogalactoside (TMG). Inhibition was absent in mutants that lacked enzyme IIA^Glc or were insensitive to inducer exclusion because enzyme IIA^Glc could not bind to the lactose carrier. Furthermore, we showed that glucose 6-phosphate caused dephosphorylation of enzyme IIA^Glc. In a mutant insensitive to enzyme IIA^Glc-mediated inducer exclusion, catabolite repression by glucose 6-phosphate in lactose-induced cells was much weaker than that in the wild-type strain, showing that inducer exclusion is the most important mechanism contributing to catabolite repression in lactose-induced cells. We discuss an expanded model of enzyme IIA^Glc-mediated catabolite repression which embodies repression by non- PTS carbon sources.