Mouse models of insulin resistance

The hallmarks of type 2 diabetes are impaired insulin action in peripheral tissues and decreased pancreatic beta-cell function. Classically, the two defects have been viewed as separate entities, with insulin resistance arising primarily from impaired insulin-dependent glucose uptake in skeletal muscle, and beta-cell dysfunction arising from impaired coupling of glucose sensing to insulin secretion. Targeted mutagenesis and transgenesis involving components of the insulin action pathway have changed our understanding of these phenomena. It appears that the role of insulin signaling in the pathogenesis of type 2 diabetes has been overestimated in classic insulin target tissues, such as skeletal muscle, whereas it has been overlooked in liver, pancreatic beta-cells, and brain, which had been thought not to be primary insulin targets. We review recent progress and try to reconcile areas of apparent controversy surrounding insulin signaling in skeletal muscle and pancreatic beta-cells.     

Control of the pattern‐recognition receptor EFR by an ER protein complex in plant immunity

In plant innate immunity, the surface‐exposed leucine‐rich repeat receptor kinases EFR and FLS2 mediate recognition of the bacterial pathogen‐associated molecular patterns EF‐Tu and flagellin, respectively. We identified the Arabidopsis stromal‐derived factor‐2 (SDF2) as being required for EFR function, and to a lesser extent FLS2 function. SDF2 resides in an endoplasmic reticulum (ER) protein complex with the Hsp40 ERdj3B and the Hsp70 BiP, which are components of the ER‐quality control (ER‐QC). Loss of SDF2 results in ER retention and degradation of EFR. The differential requirement for ER‐QC components by EFR and FLS2 could be linked to N‐glycosylation mediated by STT3a, a catalytic subunit of the oligosaccharyltransferase complex involved in co‐translational N‐glycosylation. Our results show that the plasma membrane EFR requires the ER complex SDF2–ERdj3B–BiP for its proper accumulation, and provide a demonstration of a physiological requirement for ER‐QC in transmembrane receptor function in plants. They also provide an unexpected differential requirement for ER‐QC and N‐glycosylation components by two closely related receptors.     

Effects of climate change and horticultural use on the spread of naturalized alien garden plants in Europe

Climate warming is supposed to enlarge the area climatically suitable to the naturalization of alien garden plants in temperate regions. However, the effects of a changing climate on the spread of naturalized ornamentals have not been evaluated by spatially and temporarily explicit range modelling at larger scales so far. Here, we assess how climate change and the frequency of cultivation interactively determine the spread of 15 ornamental plants over the 21st century in Europe. We coupled species distribution modelling with simulations of demography and dispersal to predict range dynamics of these species in annual steps across a 250 × 250 m raster of the study area. Models were run under four scenarios of climate warming and six levels of cultivation intensity. Cultivation frequency was implemented as size of the area used for planting a species. Although the area climatically suitable to the 15 species increases, on average, the area predicted to be occupied by them in 2090 shrinks under two of the three climate change scenarios. This contradiction obviously arises from dispersal limitations that were pronounced although we assumed that cultivation is spatially adapting to the changing climate. Cultivation frequency had a much stronger effect on species spread than climate change, and this effect was non‐linear. The area occupied increased sharply from low to moderate levels of cultivation intensity, but levelled off afterwards. Our simulations suggest that climate warming will not necessarily foster the spread of alien garden plants in Europe over the next decades. However, climatically suitable areas do increase and hence an invasion debt is likely accumulating. Restricting cultivation of species can be effective in preventing species spread, irrespective of how the climate develops. However, for being successful, they depend on high levels of compliance to keep propagule pressure at a low level.     

Differential Expression of Cerebellar Metabotropic Glutamate Receptors mGLUR2/3 and mGLUR4a after the Administration of a Convulsant Drug and the Adenosine Analogue Cyclopentyladenosine

Metabotropic glutamate receptors (mGluR) play a role in synaptic transmission, neuronal modulation and plasticity but their action in epileptic activity is still controversial. On the other hand adenosine acts as a neuromodulator with endogenous anticonvulsive properties. Since cerebellum from epileptic patients has shown neuronal damage, sometimes associated with Purkinje cells loss, we have explored the effect of repetitive seizures on two types of mGluR in the cerebellum. Seizures were induced by the convulsant drug 3-mercaptopropionic acid (MP) and the effect of the adenosine analogue cyclopentyladenosine (CPA) alone or before MP administration (CPA+MP) were also evaluated. The expression of the receptors subtypes 2/3 (mGluR2/3) and 4a (mGluR4a) was assessed by immunocitochemistry. Granular cell layer was labeled with mGluR2/3 antibody and increased immunoreactivity was observed after MP (60%), CPA (53%) and CPA + MP (85%) treatments. Control cerebellum slices showed mGluR4a reactivity around Purkinje cells, while MP, CPA and CPA+MP treatment decreased this immunostaining. Repetitive administration of MP and CPA induces an increased cerebellar mGluR2/3 and a decreased mGluR4a immunostaining, suggesting a distinct participation of both receptors that may be related to the type of cell involved. A protective action and /or an apoptotic effect may not be discarded. CPA repetitive administration although increase seizure latency, cannot prevent seizure activity.     

Predators induce egg retention in prey

To prevent predation on their eggs, prey often avoid patches occupied by predators. As a result, they need to delay oviposition until they reach predator-free patches. Because many species allocate energy to egg production in a continuous fashion, it is not clear what kind of mechanism prey use to delay oviposition. We used females of the phytoseiid mite Neoseiulus cucumeris to study these mechanisms. Females were placed in patches with pollen, a food source they use for egg production, and they were exposed to another phytoseiid mite, Iphiseius degenerans, which is an intraguild predator of N. cucumeris juveniles. We found that the oviposition of N. cucumeris females on patches with the predator was lower than on patches without the predator. Cues left by the intraguild predator were not sufficient to elicit such behaviour. Females of N. cucumeris reduced oviposition when exposed to the predator by retaining the egg inside their body, resulting in a lower developmental rate once these eggs were laid. Hence, females are capable of retaining eggs, but the development of these eggs continues inside the mother’s body. In this way, females gain some time to search for less risky oviposition sites.     

Tolerance of Mesorhizobium type strains to different environmental stresses

The symbiosis between rhizobia and legumes is affected by different environmental conditions. Our aims were to evaluate stress tolerance of Mesorhizobium species and investigate species-specific stress response mechanisms. Tolerance of Mesorhizobium type strains to temperature, salt and pH stress was evaluated. Mesorhizobium thiogangeticum showed highest growth with 1.5% NaCl and Mesorhizobium ciceri at pH 5. Mesorhizobium plurifarium showed higher growth at 37°C. SDS-PAGE analysis revealed changes in the protein profiles, namely the overexpression of a 60 kDa protein, following heat stress. Under salt stress, five overexpressed proteins were identified in M. plurifarium and M. thiogangeticum. Northern analysis revealed an increase in groEL expression in Mesorhizobium huakuii and Mesorhizobium septentrionale after heat shock; by contrast, a decrease was detected in Mesorhizobium albiziae and M. thiogangeticum, upon salt shock. A high diversity in tolerance to temperature, salt and pH stress was detected among Mesorhizobium species. M. thiogangeticum and M. ciceri are moderately halophilic and acidophilic, respectively. Several proteins, overproduced in different strains, may be involved in stress tolerance. groEL expression increased upon heat and decreased upon salt shock. To our knowledge, this is the first study focusing tolerance to temperature, salt and pH stress, as well as groEL expression, in Mesorhizobium type strains.     

Microbial community associated with the colonial ascidian Cystodytes dellechiajei

The ascidian Cystodytes dellechiajei (Della Valle, 1877) (phylum Chordata, class Ascidiacea, family Polycitoridae) is a colonial tunicate that inhabits benthic rock environments in the Atlantic, Pacific and Indian Oceans, as well as the Mediterranean Sea. Its life cycle has two phases, the adult sessile colony and the free-living larva. Both adult zooids and larvae are surrounded by a protective tunic that contains several eukaryotic cell lines, is composed mainly of acidic mucopolysacharides associated with collagen and elastin-like proteins, and is covered by a thin cuticle. The microbiota associated with the tunic tissues of adult colonies and larva of C. dellechiajei has been examined by optical, confocal and electron microscopy and by fluorescence in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), and 16S rRNA gene clone library analysis. Microscopy analyses indicated the presence inside the tunic, both for the adult and the larva, of a dense community of Bacteria while only the external surface of colony cuticle was colonized by diatoms, rodophyte algae and prokaryotic-like epiphytes. Transmission electron microscopy showed tunic eukaryotic cells that were engulfing and lysing bacteria. 16S rRNA gene analyses (DGGE and clone libraries) and FISH indicated that the community inside the tunic tissues of the adults and larvae was dominated by Alphaproteobacteria. Bacteria belonging to the phyla Gammaproteobacteria and Bacteroidetes were also detected in the adults. Many of the 16S rRNA gene sequences in the tunic tissues were related to known aerobic anoxygenic phototrophs (AAP), like Roseobacter sp. and Erythrobacter sp. In order to check whether the gene pufM, coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis, was being expressed inside the ascidian tissues, two libraries, one for an adult colony and one for larva, of cDNA from the expressed pufM gene were also constructed. The sequences most frequently (64% for colony and 67% for larva) retrieved from these libraries presented > 90% aa identity with the pufM gene product of the Roseobacter-like group, a cluster of AAP widely detected in marine planktonic environments.     

Autofluorescence imaging for recurrence detection in skin cancer postoperative scars

This clinical study is a first attempt to use autofluorescence for recurrence diagnosis of skin cancer in postoperative scars. The proposed diagnostic parameter is based on a reduction in scar autofluorescence, evaluated in the green spectral channel. The validity of the method has been tested on 110 postoperative scars from 56 patients suspected of non‐melanoma skin cancer, with eight patients (13 scars) available for the repeated examination. The recurrence diagnosis within a scar has been made after two subsequent autofluorescence check‐ups, representing the temporal difference between the scar autofluorescence amplitudes as a vector. The recognition of recurrence has been discussed to represent the significant deviations from the value of vector angle θ. This new autofluorescence‐based method can be easily integrated into the postoperative monitoring of surgical scars and can help diagnose the recurrence of skin cancer from the early stage of scar development.