Reversible inhibition of the pollen germination and the stigma penetration in Crocus vernus ssp. vernus (Iridaceae) following fumigations with NO2, CO, and O3 Gases

We assessed the pollen hydration, the pollen germination, and the stigma papilla penetration of CROCUS VERNUS subsp. VERNUS (Iridaceae) after 2 h fumigations with O (3), NO (2), and CO gases within humidified (90 - 100 % RH) box experiments. When the pollen and the pistil were separately fumigated, the pollen retained the capacity to emit a tube which penetrated papilla, and the stigma papillae retained the receptivity; when the pistils were first pollinated and then fumigated, the capacity of pollen to hydrate was not affected, but the germination was significantly reduced. The vulnerability to gases became evident at 0.3 ppm O (3), 0.2 ppm NO (2), and 0.5 ppm CO. The inhibition curves as a function of the gas concentrations were of an exponential type, and they saturated at 2 ppm NO (2), 25 ppm CO, and 0.5 ppm O (3), with germination percentages of 17 %, 27 %, and 60 %, respectively. Both the pollen germination and the papilla penetration were fully restored by prolonging for 60 - 90 min the incubation at 90 - 100 % RH, after the cessation of fumigations. The vulnerability of the pollen-papilla system is discussed.     

Predicting haplotype carriers from SNP genotypes in Bos taurus through linear discriminant analysis

Background

SNP (single nucleotide polymorphisms) genotype data are increasingly available in cattle populations and, among other things, can be used to predict carriers of specific haplotypes. It is therefore convenient to have a practical statistical method for the accurate classification of individuals into carriers and non-carriers. In this paper, we present a procedure combining variable selection (i.e. the selection of predictive SNPs) and linear discriminant analysis for the identification of carriers of a haplotype on BTA19 (Bos taurus autosome 19) known to be associated with reduced cow fertility. A population of 3645 Brown Swiss cows and bulls genotyped with the 54K SNP-chip was available for the analysis.

Results

The overall error rate for the prediction of haplotype carriers was on average very low (∼≤1%). The error rate was found to depend on the number of SNPs in the model and their density around the region of the haplotype on BTA19. The minimum set of SNPs to still achieve accurate predictions was 5, with a total test error rate of 1.59.

Conclusions

The paper describes a procedure to accurately identify haplotype carriers from SNP genotypes in cattle populations. Very few misclassifications were observed, which indicates that this is a very reliable approach for potential applications in cattle breeding.     

The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis

Plant organelle function must constantly adjust to environmental conditions, which requires dynamic coordination. Ca²⁺ signaling may play a central role in this process. Free Ca²⁺ dynamics are tightly regulated and differ markedly between the cytosol, plastid stroma, and mitochondrial matrix. The mechanistic basis of compartment-specific Ca²⁺ dynamics is poorly understood. Here, we studied the function of At-MICU, an EF-hand protein of Arabidopsis thaliana with homology to constituents of the mitochondrial Ca²⁺ uniporter machinery in mammals. MICU binds Ca²⁺ and localizes to the mitochondria in Arabidopsis. In vivo imaging of roots expressing a genetically encoded Ca²⁺ sensor in the mitochondrial matrix revealed that lack of MICU increased resting concentrations of free Ca²⁺ in the matrix. Furthermore, Ca²⁺ elevations triggered by auxin and extracellular ATP occurred more rapidly and reached higher maximal concentrations in the mitochondria of micu mutants, whereas cytosolic Ca²⁺ signatures remained unchanged. These findings support the idea that a conserved uniporter system, with composition and regulation distinct from the mammalian machinery, mediates mitochondrial Ca²⁺ uptake in plants under in vivo conditions. They further suggest that MICU acts as a throttle that controls Ca²⁺ uptake by moderating influx, thereby shaping Ca²⁺ signatures in the matrix and preserving mitochondrial homeostasis. Our results open the door to genetic dissection of mitochondrial Ca²⁺ signaling in plants.     

Signal enhancement in DNA microarray using dye doped silica nanoparticles: application to human papilloma virus (HPV) detection

DNA microarray is a powerful tool for the parallel of nucleic acids and other biologically significant molecules. In this communication we report an easy and cheap synthesis route for incorporating organic dyes into monodisperse inorganic silica nanoparticles and their application on the detection of carcinogenic risky Human Papilloma Virus using DNA microarray technology. We correlate our system with conventional direct dyes and commercial quantum dots, with a promising increase in optical signal, and a related decrease of the limit of detection, thus giving a remarkable improvement in this technique towards early diagnosis of diseases and trace level detection of dangerous biological contaminants.     

Skeletal muscle regeneration in mice is stimulated by local overexpression of V1a-vasopressin receptor

Skeletal muscle has a remarkable capacity to regenerate after mechanical or pathological injury. We show that the V1a receptor (V1aR) for vasopressin, a potent myogenic-promoting factor that stimulates differentiation and hypertrophy in vitro, is expressed in mouse skeletal muscle and modulated during regeneration after experimental injury. We used gene delivery by electroporation to overexpress the myc-tagged vasopressin V1aR in specific muscles, thus sensitizing them to circulating vasopressin. The correct localization on the surface of the fibers of the recombinant product was demonstrated by confocal immunofluorescence directed against the myc tag. V1aR overexpression dramatically enhanced regeneration. When compared with mock-transfected controls, V1aR overexpressing muscles exhibited significantly accelerated activation of satellite cells and increased expression of differentiation markers. Downstream of V1aR activation, calcineurin was strongly up-regulated and stimulated the expression of IL-4, a potent mediator of myogenic cell fusion. The central role of calcineurin in mediating V1aR-dependent myogenesis was also demonstrated by using its specific inhibitor, cyclosporine A. This study identifies skeletal muscle as a physiological target of hormones of the vasopressin family and reveals a novel in vivo role for vasopressin-dependent pathways. These findings unveil several steps, along a complex signaling pathway, that may be exploited as potential targets for the therapy of diseases characterized by altered muscle homeostasis and regeneration.     

Assembly and characterization of pandemic influenza A H1N1 genome in nasopharyngeal swabs using high-throughput pyrosequencing

De novo high-throughput pyrosequencing was used to detect and characterize 2009 pandemic influenza A (H1N1) virus directly in nasopharyngeal swabs in the context of the microbial community. Data were generated with a prior sequence independent amplification by 454 pyrosequencing on GS-FLX platform (Roche). Influenza A assembled reads allowed near full-length genome reconstruction with the simultaneous analysis of site-specific heterogeneity. The molecular approach applied proved to be a powerful tool to characterize the new pandemic H1N1 influenza virus in clinical samples. This approach could be of great value in identifying possibly new reassortants that may occur in the near future.     

Single-point mutations of a lysine residue change function of Bax and Bcl-xL expressed in Bax- and Bak-less mouse embryonic fibroblasts: novel insights into the molecular mechanisms of Bax-induced apoptosis

Members of the Bcl-2 family play key roles as proapoptotic (e.g., Bax) and antiapoptotic (e.g., Bcl-x(L)) regulators of programmed cell death. We previously identified the mitochondrial potassium channel Kv1.3 as a novel target of Bax. Incubating Kv1.3-positive isolated mitochondria with Bax triggered apoptotic events, whereas Kv1.3-deficient mitochondria were resistant to this stimulus. Mutation of Bax at lysine 128 (BaxK128E) abrogated its effects on Kv1.3 and the induction of apoptotic changes in mitochondria. These data indicate a toxin-like action of Bax on Kv1.3 to trigger at least some of the mitochondrial changes typical for apoptosis. To gain insight into the mechanism of Bax-Kv1.3 interaction, we mutated Glu158 of Bcl-x(L) (corresponding to K128 in Bax) to lysine. This substitution turned Bcl-x(L) proapoptotic. Transfection of double knockout (Bax(-/-)/Bak(-/-)) mouse embryonic fibroblasts (DKO MEFs) with either wild-type Bax, BaxK128E, or Bcl-x(L)E158K showed that apoptosis induced by various stimuli was defective in DKO MEFs and BaxK128E-transfected cells, but was recovered upon transfection with Bcl-xLE158K or wild-type Bax. Both wild-type Bax and BaxK128E can form similar ion-conducting pores upon incorporation into planar lipid bilayers. Our results point to a physiologically relevant interaction of Bax with Kv1.3 and further indicate a crucial role of a distinct lysine in determining the proapoptotic character of Bcl2-family proteins.