FOSSIL ALGAE FROM SAUDI ARABIA REVISITED

New sampling of surface sections, east of Unayzah, Qassim District and in the vicinity of Riyadh has revealed new information on the occurrence of fossil algae in the Late Permian, Middle to Late Jurassic and Late Cretaceous of central Saudi Arabia. This includes the finding of the blue-green alga, Girvanella sp., the red algae Solenopora sp. and Archaeolithothamnium sp. and the dasycladacean algae Griphoporella sp., Heteroporella cf. H. lusitanica (Ramalho), Heteroporella morillonensis (Bernier), Mizza cf. M. velebitana (Schubert) and Trinocladus cf. T. perplexus (Elliott). The biostratigraphy and the environment of deposition of the algae and the algal bearing rocks are discussed

Structural modifications in Bermuda grass [Cynodon dactylon (L.) Pers.] ecotypes for adaptation to environmental heterogeneity

IntroductionIt is well known that different ecotypes adopt different mechanisms to survive under environmental stress conditions. In this regard, each ecotype showed different type of modifications for their existence in a specific habitat that reflects to their ecological success.MethodsHere, differently adapted ecotypes of Bermuda grass [Cynodon dactylon (L.) Pers.] were collected to evaluate their differential structural and functional modifications that are specific to cope with environmental stress conditions. The soil that adheres ecotypes roots were highly saline in case of DF-SD (Derawar Fort-Saline Desert), UL-HS (Ucchali Lake-Hyper Saline) and G-SSA (Gatwala-Saline Semiarid) ecotypes. Soils of S- HS (Sahianwala-Hyper Saline), S-SW (Sahianwala-Saline Wetland) and PA-RF (Pakka Anna-Reclaimed Field) were basic (pH 9 to 10). Soils of UL-HS and PA- HS (Pakka Anna-Hyper Saline), KKL-S (Kalar Kahar Lake-Saline), BG-NS (Botanic Garden-Non Saline) and G-SSA were rich in organic matter, and soil of BG-NS and DF-SD were rich in minerals. Anatomical modifications were performed by using the free hand sectioning technique and light microscopy.Results and DiscussionDF-SD is one of the best ecotypes which showed anatomical modifications to cope with environmental changes. These modifications included stem cross-sectional area and leaf sheath thickness that contribute towards water storage, vascular tissues for proficient translocation of solutes and trichomes that provide resistance to water loss. On the other hand, sclerification in root is the only notable modification in the Gatwala Saline Semiarid (G-SSA) ecotype from saline arid habitat where rainfall is not as low as in the Cholistan Desert. Two ecotypes from hyper-saline wetlands, UL-HS and KL-HS showed increased number and size of vascular tissue, central cavity and sclerification in stem which are important for solutes conduction, water loss and salts bulk movement, respectively. The ecotype from reclaimed site was not much different from its counterpart from hyper-saline dryland. Overall, anatomical modifications to maintain water conservation are key mechanisms that have been identified as mediating stress tolerance in C. dactylon ecotypes

Bacterial Pili exploit integrin machinery to promote immune activation and efficient blood-brain barrier penetration

Group B Streptococcus (GBS) is the leading cause of meningitis in newborn infants. Bacterial cell surface appendages, known as pili, have been recently described in streptococcal pathogens, including GBS. The pilus tip adhesin, PilA, contributes to GBS adherence to blood-brain barrier (BBB) endothelium; however, the host receptor and the contribution of PilA in central nervous system (CNS) disease pathogenesis are unknown. Here we show that PilA binds collagen, which promotes GBS interaction with the α2β1 integrin resulting in activation of host chemokine expression and neutrophil recruitment during infection. Mice infected with the PilA-deficient mutant exhibit delayed mortality, a decrease in neutrophil infiltration and bacterial CNS dissemination. We find that PilA-mediated virulence is dependent on neutrophil influx as neutrophil depletion results in a decrease in BBB permeability and GBS–BBB penetration. Our results suggest that the bacterial pilus, specifically the PilA adhesin, has a dual role in immune activation and bacterial entry into the CNS

Yield of soybean genotypes identified through GGE biplot and path analysis.

Genotype x environment (GxE) interaction is an important source of variation in soybean yield, which can significantly influence selection in breeding programs. This study aimed to select superior soybean genotypes for performance and yield stability, from data from multienvironment trials (METs), through GGE biplot analysis that combines the main effects of the genotype (G) plus the genotype-by-environment (G×E) interaction. As well as, through path analysis, determine the direct and indirect influences of yield components on soybean grain yield, as a genotype selection strategy