Analysis of ssb mutations in vivo implicates SSB protein in two distinct pathways of SOS induction and in recombinational DNA repair

Site-directed mutations in the Escherichia coli ssb gene were tested for the ability to complement a chromosomal ssb deletion for viability, and only the ssb W54→G mutation failed to do so at the pSC101 copy level. Non-aromatic amino acid substitutions for SSB Trp-54 ( ssb W54→L and ssb W54→S) produced the greatest effects on in vivo protein function including altered marker linkage subsequent to generalized transduction, extreme UV sensitivity, and a lack of ability to support SOS induction. Additionally, the ssb-113 ( ssb P176→S) mutation demonstrated the existence of both uvrA -dependent and uvrA -independent components of SOS induction. Although nucleotide excision repair appeared unaffected by alterations in the SSB protein, the mutational analysis suggests a direct role for SSB in recombinational repair.     

The preparation and characterisation of some complexes of iron(II) with amino acids

The following complexes of iron(II) with the amino acids glycine, alanine, phenylglycine, phenylalanine, leucine, serine, aspartic acid, glutamic acid, glutamine, tryptophan, histidine, methionine, S-methylcysteine, cystine, and glycylglycine have been isolated: Fe(Gly)₂, Fe(Ala)₂, Fe(Phegly)₂, Fe(Phe)₂·2H₂0, Fe(Leu)₂·2H₂0, Fe(Ser)₂, Fe(Asp)·2H₂0, Fe(Glu)·2H₂0, Fe(Gln)₂, Fe(Trp)₂, Fe(His)₂·H₂0 and 2H₂0, Fe(Met)₂, Fe(MeCys)₂, Fe(CysCys) and Fe(GlyGly)₂. Their magnetic behaviour, reflectance spectra, and Mössbauer parameters are consistent with high spin, hexacoordinate iron(II), and imply extended structures involving carboxylate bridges.     

Abiotic and biotic constraints across reptile and amphibian ranges

A long‐standing macroecological hypothesis posits that species range limits are primarily determined by abiotic factors (e.g. climate) at poleward boundaries and biotic factors (e.g. competition) at equatorward boundaries. Using correlative environmental niche models we test this hypothesis for 214 amphibian and reptile species endemic to the United States (U.S.). As predicted, we find a closer association between climate and northern (poleward) range limits than at southern (equatorward) boundaries. However when we separately analyze amphibians and reptiles, only reptiles show the predicted pattern; amphibians show the opposite pattern. We also find more unoccupied, but climatically habitable, area beyond species’ southern range limits for reptiles but not amphibians. This suggests that factors other than climate limit distributions at southern boundaries for reptiles and at northern boundaries for amphibians. These contrasting results suggest that even in the same biogeographic regions, this macroecological hypothesis does not hold. Further studies should investigate, preferably via experimental approaches, the proximate and ultimate mechanisms responsible for range limits.     

Evidence of selection signatures that shape the Persian cat breed

The Persian cat is mainly characterized by an extremely brachycephalic face as part of the standard body conformation. Despite the popularity, world-wide distribution, and economic importance of the Persian cat as a fancy breed, little is known about the genetics of their hallmark morphology, brachycephaly. Over 800 cats from different breeds including Persian, non-Persian breeds (Abyssinian, Cornish Rex, Bengal, La Perm, Norwegian Forest, Maine Coon, Manx, Oriental, and Siamese), and Persian-derived breeds (British Shorthair, Scottish Fold, Selkirk Rex) were genotyped with the Illumina 63 K feline DNA array. The experimental strategy was composed of three main steps: (i) the Persian dataset was screened for runs of homozygosity to find and select highly homozygous regions; (ii) selected Persian homozygous regions were evaluated for the difference of homozygosity between Persians and those considered non-Persian breeds, and, (iii) the Persian homozygous regions most divergent from the non-Persian breeds were investigated by haplotype analysis in the Persian-derived breeds. Four regions with high homozygosity (H > 0.7) were detected, each with an average length of 1 Mb. Three regions can be considered unique to the Persian breed, with a less conservative haplotype pattern in the Persian-derived breeds. Moreover, two genes, CHL1 and CNTN6 known to determine face shape modification in humans, reside in one of the identified regions and therefore are positional candidates for the brachycephalic face in Persians. In total, the homozygous regions contained several neuronal genes that could be involved in the Persian cat behavior and can provide new insights into cat domestication.