Antagonism of the ATP-gated P2X7 receptor: a potential therapeutic strategy for cancer

Purinergic Signalling - The P2X receptor 7 (P2X7R) is a plasma membrane receptor sensing extracellular ATP associated with a wide variety of cellular functions. It is most commonly expressed on...     

Structural changes of vegetation and its association with microclimate in a successional gradient of low thorn forest in northeastern Mexico

Understanding how microclimate and vegetation are associated during secondary succession is of primary importance for plant conservation in the face of the increasing land cover modification. However, these patterns are still unstudied for many plant communities. This study aimed to evaluate the structure (species richness, Shannon's diversity index, Simpson´s dominance index, abundance of each species, average height of species, species cover (%), species composition, and indicator values) of a low thorn forest fragment and to analyze its relation with microclimate along a successional gradient. Four stages of succession were delimited by the analysis of Landsat images, in the state of Tamaulipas, northeast Mexico. Statistical models incorporated species richness, diversity indices, abundance, height, and cover, as variables for searching differences between stages, or to evaluate microclimate associations. A total of 70 species, 54 genera, and 27 families were determined. Height of tree layer was the most important variable for discrimination of the successional stages. Conserved areas differed floristically from other stages, associated mainly with the lowest values of wind speed originated by tree layer characteristics. A significant association between species and microclimate was found, being wind speed and relative humidity the most important variables. Some species, due to their high importance values and their patterns of association with microclimate, may be considered as key taxa for low thorn forest, which is a threatened semitropical community in northeast Mexico. Conserved and late successional areas account for climatic regulation of this plant community, and the importance of these forest patches may be considered when establishing biodiversity protection areas.

     

Spatial co‐localisation of extreme weather events: a clear and present danger

Extreme weather events have become a dominant feature of the narrative surrounding changes in global climate with large impacts on ecosystem stability, functioning and resilience; however, understanding of their risk of co‐occurrence at the regional scale is lacking. Based on the UK Met Office’s long‐term temperature and rainfall records, we present the first evidence demonstrating significant increases in the magnitude, direction of change and spatial co‐localisation of extreme weather events since 1961. Combining this new understanding with land‐use data sets allowed us to assess the likely consequences on future agricultural production and conservation priority areas. All land‐uses are impacted by the increasing risk of at least one extreme event and conservation areas were identified as the hotspots of risk for the co‐occurrence of multiple event types. Our findings provide a basis to regionally guide land‐use optimisation, land management practices and regulatory actions preserving ecosystem services against multiple climate threats.     

Flower power: floral reversion as a viable alternative to nodal micropropagation in Cannabis sativa.

In Vitro Cellular & Developmental Biology - Plant - The legalization of recreational and medicinal Cannabis sativa L. has been gaining global momentum, therefore increasing interest in Cannabis...     

Characterization of the Nit6803 nitrilase homolog from the cyanotroph Pseudomonas fluorescens NCIMB 11764

We report the purification and characterization of a nitrilase (E.C. 3.5.5.1) (Nit11764) essential for the assimilation of cyanide as the sole nitrogen source by the cyanotroph, Pseudomonas fluorescens NCIMB 11764. Nit11764, is a member of a family of homologous proteins (nitrile_sll0784) for which the genes typically reside in a conserved seven-gene cluster known as Nit1C. The physical properties and substrate specificity of Nit11764 resemble those of Nit6803, the current reference protein for the family, and the only true nitrilase that has been crystallized. The substrate binding pocket of the two enzymes places the substrate in direct proximity to the active site nucleophile (C160) and conserved catalytic triad (Glu44, Lys126). The two enzymes exhibit a similar substrate profile, however, for Nit11764, cinnamonitrile, was found to be an even better substrate than fumaronitrile the best substrate previously identified for Nit6803. A higher affinity for cinnamonitrile (Km 1.27 mM) compared to fumaronitrile (Km 8.57 mM) is consistent with docking studies predicting a more favorable interaction with hydrophobic residues lining the binding pocket. By comparison, 3,4-dimethoxycinnamonitrile was a poorer substrate the substituted methoxyl groups apparently hindering entry into the binding pocket. in situ ¹H NMR studies revealed that only one of the two nitrile substituents in the dinitrile, fumaronitrile, was attacked yielding trans-3-cyanoacrylate (plus ammonia) as a product. The essentiality of Nit11764 for cyanotrophy remains uncertain given that cyanide itself is a poor substrate and the catalytic efficiencies for even the best of nitrile substrates (~5 × 10³ M^?1 s^?1) is less than stellar.     

A reconsideration of Gallicolumba (Aves: Columbidae) relationships using fresh source material reveals pseudogenes,chimeras, and a novel phylogenetic hypothesis

Phylogenetic analyses of nuclear and mitochondrial DNA sequences were used to test a recent phylogenetic hypothesis for the avian genus Gallicolumba that relied heavily on preserved museum study skins for DNA samples. Our comparisons show that several published gene sequences represent pseudogenes or chimeras of multiple taxa, and these sequences had an adverse influence on phylogeny estimation. A new phylogenetic hypothesis strongly supports the monophyly of Philippine bleeding-hearts, the monophyly of Gallicolumba sensu stricto, and places Leucosarcia as part of an Australasian radiation rather than sister to Alopecoenas. These findings clarify Gallicolumba biogeography and also highlight the need for greater caution in the use of suboptimal source material in molecular systematic studies.     

Muscle Gene Expression Associated with Increased Marbling in Beef Cattle

The objective of this study was to identify specific bovine genes expressed within skeletal muscle that are associated with intramuscular fat deposition. Twenty-eight Angus-Simmental cross steers and heifers were harvested at the University of Illinois Meat Science Laboratory. Four pairs of animals were identified based on similar adjusted backfat thickness but differing amounts of intramuscular fat within each pair. RNA was extracted from muscle samples devoid of visible fat and microarray analysis was performed. Based on this analysis, 9 genes were selected and expression was subsequently confirmed by qPCR. Expression levels of MYH3, HOXD10, MXRA8, and CASQ2 were increased in animals with high marbling, whereas levels of NPNT, MRC1, DNER, and CYPB4 were decreased in high marbled animals. The remaining gene, ACTN2 was determined to be a false positive and was, therefore, excluded from further study. Despite the positive results of the preliminary study, associations between gene expression and intramuscular fat content did not extend to the larger population of cattle. A significant negative association existed between expression of MRC1 and marbling level (P = 0.04). Therefore, this study was unable to identify a particular skeletal muscle gene set whose expression correlated well with marbling levels in the larger population of beef cattle.     

Does interhemispheric communication relate to the bilateral function of muscles? A study of scapulothoracic muscles using transcranial magnetic stimulation

Interhemispheric connections have been demonstrated between the motor cortex controlling muscle pairs. However, these investigations have tended to concentrate upon hand muscles. We have extended these investigations to proximal muscles that control the scapula upon the trunk and help to move and stabilise the shoulder. Using a paired pulse transcranial magnetic stimulation protocol, the interhemispheric interactions between different shoulder girdle muscle pairs, serratus anterior, upper trapezius and lower trapezius were investigated. Test motor evoked potentials were conditioned using conditioning pulse intensities of 80% and 120% of active motor threshold at three different condition-test intervals, during three different tasks. Interhemispheric inhibition was observed in upper trapezius using a conditioning intensity of 120% and condition-test interval of 8 ms (17 ± 18%, p < 0.007). A trend towards inhibition was observed in lower trapezius and serratus anterior using a conditioning intensity of 120% and a condition-test interval of 8 ms (13 ± 22%; p < 0.07 and 10 ± 19% respectively; p < 0.07). No interhemispheric facilitation was evoked. The study demonstrates that a low level of interhemispheric inhibition rather than interhemispheric facilitation could be evoked between these muscle pairs.     

Hybridization and speciation

Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near‐instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky–Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock‐on effects on speciation both within and outside regions of hybridization.