Blood clot formation under flow: the importance of factor XI depends strongly on platelet count

A previously validated mathematical model of intravascular platelet deposition and tissue factor (TF)-initiated coagulation under flow is extended and used to assess the influence on thrombin production of the activation of factor XI (fXI) by thrombin and of the activation of factor IX (fIX) by fXIa. It is found that the importance of the thrombin-fXIa-fIXa feedback loop to robust thrombin production depends on the concentration of platelets in the blood near the injury. At a near-wall platelet concentration of ~250,000/μL, typical in vessels in which the shear rate is <200 s(-1), thrombin activation of fXI makes a significant difference only at low densities of exposed TF. If the near-wall platelet concentration is significantly higher than this, either because of a higher systemic platelet count or because of the redistribution of platelets toward the vessel walls at high shear rates, then thrombin activation of fXI makes a major difference even for relatively high densities of exposed TF. The model predicts that the effect of a severe fXI deficiency depends on the platelet count, and that fXI becomes more important at high platelet counts.     

Flow cytometric determination of genome size for eight commercially important fish species in China

The genome size (C value) of eight commercially important fish species in China was measured using flow cytometry. Chicken (Gallus domesticus) erythrocytes were used as reference cells. When using propidium iodide (PI) as the fluorescent dye, genome sizes were 1.09?±?0.08, 2.75?±?0.12, 1.05?±?0.05, 1.35?±?0.11, 0.99?±?0.05, 0.90?±?0.08, 0.90?±?0.07, and 0.88?±?0.07?pg for Japanese eel (Anguilla japonica), mullet (Myxocyprinus asiaticus), yellowcheek carp (Elopichthys bambusa), blunt snout bream (Megalobrama amblycephala), yellow catfish (Pelteobagrus fulvidraco), ricefield eel (Monopterus albus), mandarin fish (Siniperca chuatsi), and snakehead (Ophicephalus argus), respectively. However, genome sizes were 1.25?±?0.00, 3.08?±?0.02, 1.25?±?0.00, 1.57?±?0.01, 0.96?±?0.01, 1.00?±?0.01, 0.91?±?0.01, and 0.89?±?0.01?pg for these fishes, respectively, when 4??, 6-diamidino-2-phenylindole (DAPI) was used as the fluorescent dye. Regardless of the dye used, the more evolutionarily advanced species had a smaller genome size than those with a lower evolutionary status. For each species, we also measured the size of erythrocytes and their nucleus and evaluated the relationships between erythrocyte size, nucleus size, chromosome number, and genome size. Genome size was positively correlated with erythrocyte nucleus size and chromosome number when using PI as the fluorescent dye, but it was only correlated with erythrocyte nucleus size when DAPI was used.     

Elevational plant species richness patterns and their drivers across non-endemics,endemics and growth forms in the Eastern Himalaya

Despite decades of research, ecologists continue to debate how spatial patterns of species richness arise across elevational gradients on the Earth. The equivocal results of these studies could emanate from variations in study design, sampling effort and data analysis. In this study, we demonstrate that the richness patterns of 2,781 (2,197 non-endemic and 584 endemic) angiosperm species along an elevational gradient of 300–5,300 m in the Eastern Himalaya are hump-shaped, spatial scale of extent (the proportion of elevational gradient studied) dependent and growth form specific. Endemics peaked at higher elevations than non-endemics across all growth forms (trees, shrubs, climbers, and herbs). Richness patterns were influenced by the proportional representation of the largest physiognomic group (herbs). We show that with increasing spatial scale of extent, the richness patterns change from a monotonic to a hump-shaped pattern and richness maxima shift toward higher elevations across all growth forms. Our investigations revealed that the combination of ambient energy (air temperature, solar radiation, and potential evapo-transpiration) and water availability (soil water content and precipitation) were the main drivers of elevational plant species richness patterns in the Himalaya. This study highlights the importance of factoring in endemism, growth forms, and spatial scale when investigating elevational gradients of plant species distributions and advances our understanding of how macroecological patterns arise.     

Genetic epidemiology: Systemic lupus erythematosus

Systemic lupus erythematosus is the prototype multisystem autoimmune disease. A strong genetic component of susceptibility to the disease is well established. Studies of murine models of systemic lupus erythematosus have shown complex genetic interactions that influence both susceptibility and phenotypic expression. These models strongly suggest that several defects in similar pathways, e.g. clearance of immune complexes and/or apoptotic cell debris, can all result in disease expression. Studies in humans have found linkage to several overlapping regions on chromosome 1q, although the precise susceptibility gene or genes in these regions have yet to be identified. Recent studies of candidate genes, including Fcγ receptors, IL-6, and tumour necrosis factor-α, suggest that in human disease, genetic factors do play a role in disease susceptibility and clinical phenotype. The precise gene or genes involved and the strength of their influence do, however, appear to differ considerably in different populations.     

Marker-assisted introgression of the major bacterial blight resistance gene, <Emphasis Type="Italic">Xa21</Emphasis> and blast resistance gene, <Emphasis Type="Italic">Pi54</Emphasis> into RPHR-1005, the restorer line of the popular rice hybrid,DRRH3

The elite Indian rice hybrid, DRRH3 is highly susceptible to two major diseases, bacterial blight (BB) and blast, which limit its productivity significantly. In the present study, we have introgressed two major genes, viz., Xa21 and Pi54 conferring resistance against BB and blast, respectively into RPHR-1005, the male parent of DRRH3 through marker-assisted backcross breeding (MABB) and analyzed the backcross derived plants for their resistance against BB and blast. RPBio Patho-2 was used as a donor for both the resistance genes. Gene-specific markers were used for the foreground selection of Xa21 and Pi54 at each stage of backcrossing and markers specific for the major fertility restorer genes, Rf3 and Rf4 were used only at BC₁F₁ generation for foreground selection. Background selection was done using 62 polymorphic SSR markers and marker-assisted backcrossing was continued till BC₃ generation. At BC₃F₄, through intensive phenotype-based selections 15 promising lines (ABLs) possessing high level of resistance against BB and blast, high yield, fine-grain type, complete fertility restoration along with better panicle exsertion and taller plant type as compared to RPHR-1005 were identified and test crossed with APMS 6 A, the female parent of DRRH3. The newly derived hybrids (i.e. improved versions of DRRH3) were observed to possess high level of resistance against BB and blast along with medium-slender grain type and yield level better than or equivalent to that of DRRH3. Our study exemplifies the utility of MABB for targeted improvement of multiple traits in hybrid rice.