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Extant crocodilian jaws are subject to functional demands induced by feeding and hydrodynamics. However, the morphological and ecological diversity of extinct crocodile-line archosaurs is far greater than that of living crocodilians, featuring repeated convergence towards disparate ecologies including armoured herbivores, terrestrial macropredators and fully marine forms. Crocodile-line archosaurs, therefore, present a fascinating case study for morphological and functional divergence and convergence within a clade across a wide range of ecological scenarios. Here, we build performance landscapes of two-dimensional theoretical jaw shapes to investigate the influence of strength, speed and hydrodynamics in the morphological evolution of crocodile-line archosaur jaws, and test whether ecologically convergent lineages evolved similarly optimal jaw function. Most of the 243 sampled jaw morphologies occupy optimized regions of theoretical morphospace for either rotational efficiency, resistance to Von Mises stress, hydrodynamic efficiency or a trade-off between multiple functions, though some seemingly viable shapes remain unrealized. Jaw speed is optimized only in a narrow region of morphospace whereas many shapes possess optimal jaw strength, which may act as a minimum boundary rather than a strong driver for most taxa. This study highlights the usefulness of theoretical morphology in assessing functional optimality, and for investigating form–function relationships in diverse clades. [ABSTRACT FROM AUTHOR]

Pili synthesized by the type III secretion system of Rhizobium species strain NGR234 are essential for protein secretion and thus for efficient symbiosis with many legumes. Isolation and partial purification of these pili showed that they are composed of at least three proteins, NopA, NopB, and NopX. Using biochemical assays, we show here that these proteins interact directly with one another.

Rhizobium sp. strain NGR234 possesses a functional type three secretion system (TTSS), through which a number of proteins, called nodulation outer proteins (Nops), are delivered to the outside of the cell. A major constraint to the identification of Nops is their low abundance in the supernatants of NGR234 strains grown in culture. To overcome this limitation, a more sensitive proteomics-based strategy was developed. Secreted proteins from wild-type NGR234 were separated by two-dimensional gel electrophoresis, and the gel was compared to similar gels containing the proteins from a TTSS mutant (NGR[OMEGA]rhcN). To identify the proteins, spots unique to the NGR234 gels were analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry and the data were compared to the sequence of the symbiotic plasmid of NGR234. A nonpolar mutant of one of these proteins was generated called NopB. NopB is required for Nop secretion but inhibits the interaction with Pachyrhizus tuberosus and augments nodulation of Tephrosia vogelii. Flavonoids and a functional TTSS are required for the formation of some surface appendages on NGR234. In situ immunogold labeling and isolation of these pili showed that they contain NopB.

The type three secretion system (TTSS) encoded by pNGR234a, the symbiotic plasmid of Rhizobium sp. strain NGR234, is responsible for the flavonoid- and NodD1-dependent secretion of nodulation outer proteins (Nops). Abolition of secretion of all or specific Nops significantly alters the nodulation ability of NGR234 on many of its hosts. In the closely related strain Rhizobiumfredii USDA257, inactivation of the TI'SS modifies the host range of the mutant so that it includes the improved Glycine max variety McCall. To assess the impact of individual TTSS-secreted proteins on symbioses with legumes, various attempts were made to identify nop genes. Amino-terminal sequencing of peptides purified from gels was used to characterize NopA, NopL, and NopX, but it failed to identify SR3, a TTSS-dependent product of USDA257. By using phage display and antibodies that recognize SR3, the corresponding protein of NGR234 was identified as NopP. NopP, like NopL, is an effector secreted by the TTSS of NGR234, and depending on the legume host, it may have a deleterious or beneficial effect on nodulation or it may have little effect.

A study was conducted to analyze a fourth flagellin gene in a 21850 bp region of the Agrobacterium tumefaciens C58C1 chromosome supporting at least 20 genes concerned with flagellar structure, assembly and function. Three flagellin genes were positioned in a tandem array at the right end. Results indicated that the flagellins contribute to flagellar structure. In addition, FlA has an anomolous electrophoretic mobility that ma be due to glycosylation.

Presents information on a study which attempted to repair the DNA templates in sorghum seed extracts prior to subjecting to conventional amplification using polymerase chain reactions (PCR). Forms of the sorghum found at Qasr Ibrim in Egyptian Nubia; Materials and methods used in the study; Results.

Focuses on a study on the amplification and sequencing of DNA from preserved sorghum seeds found in Qasr Ibrim, southern Egypt. Microscopic and molecular analysis of Qasr Ibrim Sorghum seeds; Amplification using ribosomal DNA primers; Amplification using phosphoenolpyruvate carboxylase gene primers.