Effect of Azospirillum inoculation on some growth parameters and n-content of wheat,sorghum and panicum

The potential of the nitrogen fixing bacteriumAzospirillum brasilense to enhance development and increase growth of several gramineae was investigated. In both sterilized and non-sterilized systems heading and flowering occurred earlier in the inoculated plants as compared to the noninoculated ones. Total shoot and root weights, total-N content, plant height and leaf length were significantly increased by inoculation.From the Department of Agricultural Botany.     

The temperature relations of vocalization in infant Golden hamsters and Wistar rats

Environmental temperature changes are capable of evoking ultrasonic responses from the young of Wistar rats and Golden hamsters. The changes with age in the intensity of these sounds and the rate of calling are found to be related to the pattern of development of homiothermy in the two species. In the Golden hamster, the same temperature changes also evoke audible calls which show a different pattern of variation with age. These findings are discussed in comparison with those previously reported for albino mice.     

Factors affecting growth and nitrogen fixation of Spirillum lipoferum.

Spirillum lipoferum grows vigorously on malate, succinate, lactate, or pyruvate, moderately on galactose or acetate, and poorly on glucose or citrate. It reduces 15N2. Acetylene reduction rates decrease rapidly when the pH of the culture rises above 7.8. The organism is highly aerobic and had doubling times as low as 2 h when grown on NH4+. However, S. lipoferum reduces N2 well only under microaerophilic conditions. The optimal pO2 for acetylene reduction by stagnant cultures was 0.006 to 0.02 atm depending upon the cell density; aerated cultures grew well at dissolved O2 concentration corresponding to a pO2 of about 0.008 atm. Shaking S. lipoferum with air temporarily inactivates its nitrogenase; reactivation is inhibited by chloramphenicol. The organism assimilated 20 to 24 mg of N/g of organic acid oxidized during growth. The strains studied can be placed in two groups based upon their morphology and physiological characteristics.     

Response ofSetaria italica to inoculation withAzospirillum brasilense as compared toAzotobacter chroococcum

Summary Under controlled conditions in pots filled with sand, vermiculite and field soil, inoculation withA. brasilense-Cd ATCC 29729 or withAzotobacter chroococcum caused increases above controls in the weight and N content of panicles ofSetaria italica. In no case, however, did N increases in test plants exceed the initial total N content. High acetylene reduction activities (1,000–2,000 nmole/h/pot) could be found only in plants inoculated withAzospirillum. Inoculation withAzospirillum (strain-Cd) in the field caused a significant increase above noninoculated controls of 18.5% in shoot dry weight, ofSetaria italica. Azotobacter caused a non significant increase of 8%. No significant differences were found between yields ofSetaria italica grown in soil inoculated withA. chroococcum, and those of plants grown in the presence ofA. vinelandii. A. brasilense-Cd was more effective in the field thanA. brasilense Sp-7 ATCC 29145. The results suggest that Azospirillum may increase yields ofS. italica more efficiently than Azotobacter under local field conditions.     

Biophysical Characterization of the Tandem FHA Domain Regulatory Module from the Mycobacterium tuberculosis ABC Transporter Rv1747

1. Download high-res image (236KB)
2. Download full-size image

     

Effect ofAzospirillum inoculation on nitrogen fixation and growth of several winter legumes

Summary Inoculation of naturally nodulatedPisum sativum L. (garden pea) withAzospirillum in the greenhouse caused a significant increase in nodule numbers above controls. Field inoculation of garden peas in the winter 1981–1982 andCicer arietinum L. (chick pea), in winter 1982–1983, withAzospirillum one week after plant emergence, produced a significant increase in seed yield, but did not affect plant dry matter yield. ForVicia sativa L. (vetch) grown in soil in the greenhouse and in the field for forage, winter 1980–1981, inoculation significantly increased dry matter yield, %N, N-content, and acetylene reduction (nitrogen fixation) activity. InHedysarum coronarium L. (sulla clover), winter 1981–1982, inoculated with both its specificRhizobium (by the slurry method) andAzospirillum, 7 days after emergence, there was an increase in acetylene reduction above controls inoculated withRhizobium alone. These results suggest that it is possible, under conditions tested in this work, to increase nodulation, nitrogen fixation, and crop yields of winter legumes by inoculation withAzospirillum.     

Phylogenetic distinctiveness of Middle Eastern and Southeast Asian village dog Y chromosomes illuminates dog origins

Modern genetic samples are commonly used to trace dog origins, which entails untested assumptions that village dogs reflect indigenous ancestry or that breed origins can be reliably traced to particular regions. We used high-resolution Y chromosome markers (SNP and STR) and mitochondrial DNA to analyze 495 village dogs/dingoes from the Middle East and Southeast Asia, along with 138 dogs from >35 modern breeds to 1) assess genetic divergence between Middle Eastern and Southeast Asian village dogs and their phylogenetic affinities to Australian dingoes and gray wolves (Canis lupus) and 2) compare the genetic affinities of modern breeds to regional indigenous village dog populations. The Y chromosome markers indicated that village dogs in the two regions corresponded to reciprocally monophyletic clades, reflecting several to many thousand years divergence, predating the Neolithic ages, and indicating long-indigenous roots to those regions. As expected, breeds of the Middle East and East Asia clustered within the respective regional village dog clade. Australian dingoes also clustered in the Southeast Asian clade. However, the European and American breeds clustered almost entirely within the Southeast Asian clade, even sharing many haplotypes, suggesting a substantial and recent influence of East Asian dogs in the creation of European breeds. Comparison to 818 published breed dog Y STR haplotypes confirmed this conclusion and indicated that some African breeds reflect another distinct patrilineal origin. The lower-resolution mtDNA marker consistently supported Y-chromosome results. Both marker types confirmed previous findings of higher genetic diversity in dogs from Southeast Asia than the Middle East. Our findings demonstrate the importance of village dogs as windows into the past and provide a reference against which ancient DNA can be used to further elucidate origins and spread of the domestic dog.     

Azospirillum as a potential inoculant for agriculture

Azospirillum sp. contribute to increased yields of cereal and forage grasses by improving root development in properly colonized roots, increasing the rate of water and mineral uptake from the soil, and by biological nitrogen fixation. A better understanding of the basic biology of the Azospirillum—root interaction, aided by the application of genetic engineering techniques, may lead to greater efficiency in its use as a biofertilizer.     

Establishment and movement of egg regions revealed by the size class of yolk platelets in Xenopus laevis

Sizes of yolk platelets were measured in sections of oocytes and embryos in Xenopus. It was found that the average size of the largest group of platelets in cells differed between germ layers of neurulae. It was small (3 to 5 m) in the ectoderm, medium-sized (5 to 8 µm) in the mesoderm, and large (over 8 m) in the endoderm. Platelets of these size classes formed layers in egg, the yolk gradient, by the end of oocyte maturation. The yolk gradient contained products of the mitochondrial cloud and a part of the germinal vesicle material at certain positions. The layers of small, medium and large platelets in the egg changed their locations to distribute to the ectoderm, mesoderm and endoderm of neurulae, respectively. The yolk layers in the egg thus represented different prospective fates, and a figure describing the locations of these layers could be regarded as a fate map for the one-cell stage. Most of the marginal blastomeres of embryos at cleavage stages consisted of a few parts with different prospective fates. Results were discussed with reference to available fate maps for cleavage stage embryos.     

The effect of glucose and lactose on beta-D-galactosidase activity and formation of sclerotia in Sclerotium rolfsii.

Addition of 0.5% (w/v) lactose to a glucose-mineral mdeium (SM) induced formation of sclerotia and beta-D-galactosidase (beta-D-galactoside galactohydrolase)(EC 3.2.1.23) synthesis in Sclerotium rolfsii types A and R; These effects as well as lactose uptake were inversely related to glucose concentration within the tested range of 0.5 to 2.5% (w/v). Transfer of lactose-grown colonies to a glucose-supplemented medium nullified the inducible effect of lactose on formation of sclerotia, whereas transfer to water agar did not. It is concluded that glucose nullifies the effect of lactose on S. rolfsii by interfering with its active uptake.