Complex Transitions Between C3 and C4 Photosynthesis During the Evolution of Paniceae: A Phylogenetic Case Study Emphasizing the Position of Steinchisma Hians (Poaceae), A C3-C4 Intermediate

A two-tiered, nested molecular phylogenetic study of panicoid grasses to explore character state transitions between the C3 and C4 adaptive syndromes is presented. A broad survey of 92 panicoid species was sampled for the grass-specific insert sequence in the chloroplast RNA polymerase locus (rpoC2), combining published and unpublished sequences. This portion of the study also included an intensive phylogenetic investigation of one clade of seven species that included Steinchisma hians, which is notable for exhibiting intermediacy between the C3 and C4 photosynthetic types. Both rpoC2 data and previously published sequences of the F subunit of an NADH-dependent dehydrogenase were analyzed together for this small group. A rigorous phylogenetic investigation of S. hians and 13 other species of Panicoideae included in the broad survey was then performed with sequences of both rpoC2 and the externally transcribed spacer region of the nuclear ribosomal repeat. These 14 species were selected to maximize representation among photosynthetic subtypes. Combined analysis resolved single origins of two photosynthetic subtypes. A reversion of C4 to C3 photosynthesis during the evolution of the lineage that includes S. hians is identified. These and other recent results indicate that repeated reversions from C4 to C3 have occurred. The C3 species Panicum laxum has a strongly supported sister group relationship to S. hians (C3-C4). The most parsimonious interpretation is that S. hians represents an incipient reversal from C3 to C4 photosynthesis, beginning with the capacity to compartmentalize photorespiratory metabolism in the bundle sheath tissue

Phylogenetically Widespread Multiple Paternity in New World Natricine Snakes

We used microsatellite DNA markers to identify the extent to which multiple paternity within litters occurs among species of New World natricine snakes. We selected seven species to represent the three major clades of Natricinae and all three subclades of the gartersnake clade. Microsatellite DNA genotyping of dams and litters confirmed multiple paternity within litters of six species, including Thamnophis radix, T. sauritus, Storeria dekayi, S. occipitomaculata, Nerodia rhombifer, and Regina septemvittata. Multiple paternity was not evident in one litter of nine Thamnophis melanogaster. Together with published data documenting multiple paternity in T. bulteri, T. elegans, T. sirtalis, and N. sipedon, these results confirm the phylogenetically widespread occurrence of multiple paternity among New World natricines, emphasizing the need to consider phylogenetic (historical) explanations when analyzing snake mating systems

Soybean Leaves Contain Multiple Lipoxygenases

Chromatofocusing of soybean (Glycine max L.) leaf lipoxygenases revealed three distinct peaks of activity. Based on their isoelectric points (pis), pH optima, and mutant analysis it appears that the leaf isozymes are different from those described from mature soybean seed. At least one leaf lipoxygenase appears to differ from those found in hypocotyls. The pis of the main bands of the three leaf lipoxygenase peaks are 6.67, 5.91, and 5.67. The pH optima curves of three active fractions exhibit peaks at pH 6.2, 5.5, and 8.5, respectively. One of the fractions has two polypeptides with slightly different molecular weights, both of which react to soybean seed lipoxygenase antibodies. The other two fractions contain a polypeptide of unit molecular weight reacting with the lipoxygenase antibodies

The Mitochondrial Genome of the Peronosporomycete Saprolegnia Ferax: Organization, Gene Content, and Nucleotide Sequence

The mitochondrial genome of the peronosporomycete water mold Saprolegnia ferax has been characterized as a 46 930 bp circle containing an 8618 bp large inverted repeat (LIR). Eighteen reading frames encode identified subunits of respiratory complexes I, III, IV and V; 16 encode polypeptides of small and large mitoribosome subunits; and one encodes a subunit of the sec-independent protein translocation pathway. Of four additional putative reading frames three are homologues of those found in the related Phytophthora infestans genome. Protein encoding loci in the tightly compacted genome typically are arranged in operon-like clusters including three abutting and two overlapping pairs of reading frames. Translational RNAs include the mitochondrial small and large subunit rRNAs and 25 tRNA species. No tRNAs are encoded to enable translation of any threonine or the arginine CGR codons. The LIR separates the molecule into 19 274 bp large and 10 420 bp small single copy regions, and it encodes intact duplicate copies of four reading frames encoding known proteins, both rRNAs, and five tRNAs. Partial 39 sequences of three additional reading frames are duplicated at single copy sequence junctions. Active recombination between LIR elements generates two distinctive gene orders and uses the duplicated 39 sequences to maintain intact copies of the partially duplicated loci. Key words: mitochondria

Role of Nitric Oxide and Flavohemoglobin Homolog Genes in Aspergillus nidulans Sexual Development and Mycotoxin Production ▿ †

Flavohemoglobins are widely distributed in both prokaryotes and eukaryotes. These proteins are involved in reducing nitric oxide levels. Deletion of the Aspergillus nidulans flavohemoglobin gene fhbA induced sexual development and decreased sterigmatocystin production. Supplementation with a nitric oxide-releasing compound promoted cleistothecial formation and increased nsdD and steA expression, indicating that nitric oxide induces sexual development. This is the first study on the effect of nitric oxide on morphogenesis and secondary metabolism in fungi

Aspergillus nidulans Natural Product Biosynthesis Is Regulated by MpkB, a Putative Pheromone Response Mitogen-Activated Protein Kinase▿ †

The Aspergillus nidulans putative mitogen-activated protein kinase encoded by mpkB has a role in natural product biosynthesis. An mpkB mutant exhibited a decrease in sterigmatocystin gene expression and low mycotoxin levels. The mutation also affected the expression of genes involved in penicillin and terrequinone A synthesis. mpkB was necessary for normal expression of laeA, which has been found to regulate secondary metabolism gene clusters