Protein polymorphism inEligmodontia typus. Genetic divergence with other phyllotine cricetids

By means of gel electrophoresis of tissue extracts we have studied protein polymorphism inEligmodontia typus. The analysis was performed on specimens from five population samples collected at different sites in Patagonia (Argentina). Mean heterozygosity (\-h) and proportion of polymorphic loci (P) were determined on the basis of 19 loci. Considering all individuals as one sample, \-h gave a value of 0.16 and P was 70%. Although these values are much higher than those reported for most rodent species, they are very similar to those obtained by us for four species of the genusCalomys and forGraomys griseoflavus. There is a striking genetic identity (I_N=0.99) among populations from regions with different environmental conditions, indicating that the species possesses a common genic pool. Genetic distance with other species of the Phyllotini was estimated. D_N was lower betweenE. typus andCalomys (mean D_N=0.88) than betweenE. typus andGraomys griseoflavus (D_N=1.01). The high morphological similarity between these last two species, especially regarding those characters related to desert life adaptation, could be assigned, at least in part, to convergent evolution.     

A new species of Macrothrix (Anomopoda: Macrothricidae) from Central Mexico

Macrothrix mexicanus sp. nov. is described from central México, a transition zone between the nearctic and neotropics. All localities where it was found are over 1800 meters above sea level. It shows many resemblances with M. laticornis, M. camjatae and M. rosea but is characterized by a persistent dorsal tooth on the valve keel, a spinous papilla on the basipodite of the antenna, the second thoracic limb with a long conical sensillum between scraper 1 and the gnathobase, the endopod of trunk limb IV having two setae; the postabdomen with the dorsal margin bilobed, and the distal segment of the seta natatoria which is unusually long.Abbreviations used on figures EN Endopodite - EP Epipodite - EX Exopodite - IDL Inner distal lobe - ODL Outer distal lobe - GT Gnatobase - E1 Endite 1 - E2 Endite 2 - E3 Endite 3     

Decomposition of Eucalyptus globulus leaves and three native leaf species (Alnus glutinosa, Castanea sativa and Quercus faginea) in a Portuguese low order stream

Leaf decomposition of the exotic evergreen Eucalyptus globulus (eucalyptus), and three native deciduous tree species, Alnus glutinosa (alder), Castanea sativa (chestnut) and Quercus faginea (oak), was compared in a second order stream in Central Portugal. Changes in dry weight, nitrogen and polyphenolic compounds and microbial colonization were periodically assessed for three months.Negative exponential curves fit the leaf weight loss with time for all leaf species. Mass loss rate was in the order alder (K = 0.0161) > chestnut (K = 0.0079) > eucalyptus (K = 0.0068) > oak (K = 0.0037). Microbial colonization followed the same pattern as breakdown rates. Evidence of fungal colonization was observed in alder after 3 days in the stream, whereas it took 21 days in oak leaves to have fungal colonization. Fungal diversity was leaf species-dependent and increased with time. In all cases, percent nitrogen per unit leaf weight increased, at least, at the initial stages of decay while soluble polyphenolics (expressed as percentage per unit leaf weight) decreased rapidly in the first month of leaves immersion.Intrinsic factors such as nitrogen and polyphenolic content may explain differences in leaf decomposition. The possible incorporation of eucalyptus litter into secondary production in a reasonable time span is suggested, although community balance and structure might be affected by differences in allochthonous patterns determined by eucalyptus monocultures.     

“Bacillus thermoantarcticus” sp. nov., from Mount Melbourne,Antarctica: a novel thermophilic species

 A novel thermophilic Gram-positive bacillus, “Bacillus thermoantarcticus”, isolated from geothermal soil near the crater of Mount Melbourne, is described. The organism grows at an optimal temperature of 63^°C at pH 6.0, is oxidase-positive, catalase-negative and produces an exopolysaccharide, an exocellular xylanase, an intracellular alcohol dehydrogenase and exo- and endocellular α-glucosidase(s). The sequence of 16S rDNA is very similar to that of “Bacillus thermoglucosidasius”; however, the guanine-plus-cytosine (G+C) content is 8 mol% higher. The type strain is “Bacillus thermoantarcticus” (DSM 9572). Received : 3 February 1995/Accepted : 12 May 1995     

Pectin lyase production by Penicillium griseoroseum: Effect of tea extract, caffeine, yeast extract, and pectin

Summary Mycelial growth and production of extracellular pectin lyase by Penicillium griseoroseum at different concentrations of inducers were investigated. The fungus was cultured in mineral medium using sucrose as a carbon source and caffeine, yeast extract, tea extract or pectin as inducers. Caffeine, yeast extract and tea extract in the presence of sucrose, and tea extract alone were capable of inducing pectin lyase in P. griseoroseum, even at low concentrations.     

Biotransformation of monoterpenes and sesquiterpenes by cell suspension cultures of Achillea millefolium L. ssp. millefolium

The transformation capacity of Achillea millefolium L. ssp. millefolium (yarrow) cell suspension cultures was investigated using geraniol (50mg/l) and borneol, menthol, thymol and farnesols (25mg/l) as substrates. Apart from converting these substrates into several biotransformation products, the cell suspension cultures were also able to glycosylate both the substrates and the biotransformation products. aa]Key Words bb]Achillea millefolium L. ssp. millefolium bb]Yarrow bb]Compositae bb]Biotransformation bb]Glycosylation bb]Geraniol bb]Borneol bb]Menthol bb]Thymol bb]Farnesols     

Mapping of two plasmids from Lactobacillus helveticus ILC 54, plasmid curing and preliminary studies on their involvement in lactose metabolism and peptidase activity

Summary Two plasmids isolated from Lactobacillus helveticus strain ILC 54 were analysed by restriction digestion. A restriction map of the 14.3 and 5.6 kb plasmids is presented. Plasmid-curing studies suggest that these plasmids are involved in lactose metabolism and peptidase activity.     

A case-control study on selenium,zinc, and copper in plasma and hair of subjects affected by breast and lung cancer

The purpose of our study was to investigate the relationship between plasma and hair levels of Se, Zn, and Cu, and cancer. We selected a total of 66 patients affected by either breast (38) or lung (28) cancer. They entered into the study at the onset of disease, and before any chemical or radiotherapy. Controls were randomly selected among healthy people and were matched for sex, age, smoking habits, and residence. In the group of breast cancer, a significant decrease in hair Se was found compared to controls (p<0.01), whereas plasma Se was only slightly decreased. No difference between cases and controls was detected in both hair and plasma levels of Zn and Cu. Subjects who developed lung cancer were significantly lower in hair Zn (p<0.05) and Cu (p<0.01) than controls, whereas there was no difference with regard to Se. In addition, plasma Cu of these patients was increased as compared to controls.     

Substrate subsite recognition of the xyloglucan endo-transglycosylase or xyloglucan-specific endo-(1→4)-β-d-glucanase from the cotyledons of germinated nasturtium (Tropaeolum majus L.) seeds

We have investigated the substrate subsite recognition requirement of the xyloglucan endo-transglycosylase/xyloglucan-specific endo-(14)--d-glucanase (NXET) from the cotyledons of nasturtium seedlings. Seed xyloglucans are composed almost entirely of the Glc₄ subunits XXXG, XLXG, XXLG and XLLG, where G represents an unsubstituted glucose residue, X a xylose-substituted glucose residue and L a galactosyl-xylose-substituted glucose residue. Thus in the xyloglucan sequence shown below, the xylose (Xyl) residues at the backbone glucose (Glc) residues numbered — 3,— 2, + 2 and + 3 may be galactose-substituted, and NXET cleaves between the unsubstituted glucose at — 1 and the xylose-substituted glucose at + 1, which never carries a galactosyl substituent. We have isolated the xyloglucan oligosaccharides XXXGXXXG and XLLGXLLG from NXET digests of tamarind seed xyloglucan, have modified them enzymatically using a pure xyloglucan oligosaccharide-specific -xylosidase from nasturtium seeds to give GXXGXXXG and GLLGXLLG, and have identified and compared the products of NXET action on XXXGXXXG, GXXGXXXG, XLLGXLLG and GLLGXLLG. We have also compared the molar proportions of XXXG, XLXG, XXLG and XLLG in native tamarind and nasturtium seed xyloglucans with those in NXET digests of these polysaccharides. Using these and existing data we have demonstrated that NXET action does not require xylosesubstitution at glucose residues — 4, — 2, + 1 and + 3 and that xylose substitution at + 2, is a requirement. There may also be a requirement for xylose substitution at — 3. We have demonstrated also that galactosyl substitution of a xylose residue at + 1 prevents, and at — 2 modifies, chain-cleavage. A partial model for the minimum substrate binding requirement of NXET is proposed.Abbreviations G unsubstituted glucose residue - X xylose-substituted glucose residue - L galactosylxylose-substituted glucose residue - F fucosyl-galactosylxylose-substituted glucose residue - Gal galactose - Glc glucose - HPAE high-performance anion-exchange chromatography - NXET nasturtium xyloglucan endo-transglycosylase or xyloglucan-specific endo-(14)--d-glucanase - Xyl xylose This work was funded jointly by Unilever UK and the Department of Trade and Industry (UK) via the LINK initiative Agro-Food Quality.     

Markers for selection of the rice Xa21 disease resistance gene

Six molecular markers were mapped to a 7.4-cM region of rice chromosome 11 containing the Xa21 gene, which confers resistance to the pathogen Xanthomonas oryzae pv oryzae. Three markers, RG103, 248 and 818, co-segregated with Xa21 in a population of 1141 plants. Multiple copies of all marker loci were present within the region that was introgressed from Oryza longistaminata into O. sativa. The marker loci were cloned and primers were designed that defined sequence-tagged sites. Physical mapping of the three tightly linked central markers revealed that RG103, the marker that hybridizes to the Xa21 gene, resides on a separate DNA fragment from the other two markers.Disclaimer: Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.