Codon use and the rate of divergence of land plant chloroplast genes

Codon fitnesses for chloroplast genes were estimated using the relative synonymous codon use of psbA, which has a different pattern of codon use than other chloroplast genes and is the major translation product of the chloroplast. These estimates were used to calculate the codon adaptation index (CAI) of chloroplast genes from Marchantia polymorpha, Nicotiana tabacum, and Chlamydomonas reinhardtii. The genes with the highest CAI values in M. polymorpha correspond to those that are expressed at the highest levels. The rate of divergence between M. polymorpha and both C. reinhardtii and N. tabacum is inversely related to the CAI value of the M. polymorpha gene. The data suggest that selection is acting on the synonymous codon use of the highly expressed genes of the M. polymorpha chloroplast genome. The data set is inconclusive about N. tabacum genes, but, as there is a weaker correspondence between CAI value and expression level, it suggests that selection is not operating in this lineage.      

Purification and characterization of maltooligosaccharide-forming amylase from Bacillus circulans GRS 313

A maltooligosaccharide-forming amylase that hydrolyzes starch into maltotriose and maltopentaose was found in the culture filtrate of a strain of Bacillus circulans GRS 313 isolated from local soil. The enzyme was purified by organic solvent fractionation, Sephadex G-100 gel filtration and CM-Sephadex column chromatography. Optimum pH and temperature of amylase were evaluated using response surface methodology (RSM) and were found to be 48°C and 4.9, respectively. The enzyme was stable up to 60°C and its pH stability was in the range of 5.0–8.0. The K _m and V _max of the amylase with starch were 11.66 mg/ml and 68.97 U, respectively, and the energy of activation, E _a, was 7.52 kcal/mol. Dextrin inhibited the enzyme competitively, with a K _i of 6.1 mg/ml, and glucose caused noncompetitive inhibition with a K _i of 9.5 mg/ml. The enzyme was inhibited by Hg²⁺, Mn²⁺, Fe³⁺ and Cu²⁺ and enhanced by Co²⁺ and Mg²⁺. EDTA reversed the inhibitory effect of the metals. Paper chromatographic and high-performance liquid chromatography analysis of the products of the amylolytic reaction showed the presence of maltotriose, maltotetraose, maltopentaose, maltose and glucose in the starch hydrolysate. Journal of Industrial Microbiology & Biotechnology (2002) 28, 193–200 DOI: 10.1038/sj/jim/7000220 Received 11 December 2000/ Accepted in revised form 22 October 2001     

Familial frontotemporal dementia with neuronal intranuclear inclusions is not a polyglutamine expansion disease

Background  

Many cases of frontotemporal dementia (FTD) are familial, often with an autosomal dominant pattern of inheritance. Some are due to a mutation in the tau- encoding gene, on chromosome 17, and show an accumulation of abnormal tau in brain tissue (FTDP-17T). Most of the remaining familial cases do not exhibit tau pathology, but display neuropathology similar to patients with dementia and motor neuron disease, characterized by the presence of ubiquitin-immunoreactive (ub-ir), dystrophic neurites and neuronal cytoplasmic inclusions in the neocortex and hippocampus (FTLD-U). Recently, we described a subset of patients with familial FTD with autopsy-proven FTLD-U pathology and with the additional finding of ub-ir neuronal intranuclear inclusions (NII). NII are a characteristic feature of several other neurodegenerative conditions for which the genetic basis is abnormal expansion of a polyglutamine-encoding trinucleotide repeat region. The genetic basis of familial FTLD-U is currently not known, however the presence of NII suggests that a subset of cases may represent a polyglutamine expansion disease.     

Hymenolepis nana: intestinal tissue phase in actively immunized mice.

We investigated the fate of the intestinal cestode Hymenolepis nana in immunized mice. Immunity was induced by infection with the parasite eggs. These immunized animals and unimmunized controls were then challenged with 50,000 H. nana eggs. The mice were killed 4 to 90 hr after challenge, and H. nana in the intestinal tissue were counted. At 4 hr after challenge the unimmunized and immunized animals had approximately equal numbers of oncospheres. By 12 hr there were fewer parasites in the immunized than in the unimmunized animals. At 90 hr, no H. nana were seen in the immunized mice, whereas in the unimmunized animals the median number of cysticercoids was more than 1,000. It appears, therefore, that in mice well immunized to H. nana by infection, challenge oncospheres can burrow into the intestinal tissue before they are killed. The reduced number of oncospheres in the immunized mice 12 hr after challenge, and the accumulation of eosinophils near individual oncospheres still present, indicate that an immune response to the parasite was taking place. Absence of a lymphocyte infiltration near any of the oncospheres suggests that the mechanism of immunity was not lymphocyte mediated; thus, the histopathology of the reaction is consistent with that of humoral immunity.     

Nothobranchius cooperi (Teleostei: Cyprinodontiformes): a new species of annual killifish from the Luapula River drainage,northern Zambia

Nothobranchius cooperi, Nagy, Watters and Bellstedt, new species, is described from seasonal streams and ephemeral pools associated with the upper Mansa River system in the middle Luapula drainage and systems draining into the low-lying area marginal to the southwestern part of Lake Bangweulu, in the Luapula province of northern Zambia. It belongs to the N. brieni species group. Males of Nothobranchius cooperi are distinguished from congeners by the following unique combination of characters: body scales with broad orange posterior margin, forming a highly irregular cross-barred pattern; anal fin fairly uniform orange-red with irregular to regular, light blue-green zone close to the base; caudal peduncle length 1.2–1.3 times its depth; prepelvic length 48.8–51.9% SL; and head depth 75–77% of head length. Genetic divergence of the mitochondrial COI and ND2 genes and nuclear S7 gene support the distinction of the new species from its closest known relative, N. rosenstocki and confirms its position in the N. brieni species group.