Genetic analysis of variegation mutants of pearl millet, Pennisetum glaucum

Intercrosses between different variegated lines of Pennisetum glaucum (L.) R.Br. were made to determine their allelic composition and the number of loci controlling plastid alterations. Self-pollinations of different variegated plants resulted in normal, variegated, and yellow or white progeny. Crosses among yellow stripe mutants (IP 5009, IP 9712, IP 482) resulted in normal and yellow progeny in the F1, and normal and yellow stripe in the F2 generations, indicating the complementary interaction of two loci in each cross. Reciprocal crosses between the yellow stripe mutants IP 5009 and IP 13160-1 revealed similarity in their genotypes. Progeny composition from the crosses between the white stripe mutants VCM-36 and GWS-14 indicated their genotypic similarities. Crosses between yellow stripe and white stripe mutants (IP 5009 × VCM-36, IP 482 × VCM-36) indicated differences in their genotypes. Comparison of segregation patterns in the progenies of intercrosses revealed at least 4 independent loci, any one of which in recessive condition leads to mutant phenotype(s) while the development of chlorophyll is accomplished by the complementary interaction of dominant genes at these loci. Among the recessive genotypes in the F2s from intergenotypic crosses, the mutant phenotypes fell short of expectation, indicating differential penetrance in expression

Novel magnetic properties of graphene: Presence of both ferromagnetic and antiferromagnetic features and other aspects

Investigations of the magnetic properties of graphenes prepared by different methods reveal that dominant ferromagnetic interactions coexist along with antiferromagnetic interactions in all the samples. Thus, all the graphene samples exhibit room-temperature magnetic hysteresis. The magnetic properties depend on the number of layers and the sample area, small values of both favoring larger magnetization. Molecular charge-transfer affects the magnetic properties of graphene, interaction with a donor molecule such as tetrathiafulvalene having greater effect than an electron-withdrawing molecule such as tetracyanoethyleneComment: 16 pges, 5 figure

Interspecific hybridization with Hordeum bulbosum and development of hybrids and haploids

Subrahmanyam, N.C. and Bothmer, R. von, 1987. Interspecific hybridization with Hordeum bulbosum and development of hybrids and haploids. - Hereditas 106: 119-127. Lund, Sweden. ISSN 001-0661. Received May 2, 1986.A total of 64 interspecific crossing combinations with H. bulbosum (2x and 4x) were attempted. The maximum seed set was generally very high. Progeny was obtained in 19 combinations with diploid and 13 combinations with tetraploid H. bulbosum. As a result of selective chromosome elimination, haploids were recorded in 7 interspecific combinations with diploid and 7 with tctraploid H. bulbosum. There are 7 new haploid-producing combinations, viz. H. cordobense monohaploids, H. marinum mono- and dihaploids. and H. brevisubularum di- and trihaploids in crosses with H. bulbosum (4x), H. capense dihaploids and H. murinum dihaploids with H. bulbosum (2x). The theory of a hierarchical chromosome elimination system is strengthened by the present results.Roland yon Bothmer, Department of Crop Genetics and Breeding, Swedish University of Agricultural Sciences, S-268 00 Svalov, Sweden

Femtosecond carrier dynamics and saturable absorption in graphene suspensions

Nonlinear optical properties and carrier relaxation dynamics in graphene, suspended in three different solvents, are investigated using femtosecond (80 fs pulses) Z-scan and degenerate pumpprobe spectroscopy at 790 nm. The results demonstrate saturable absorption property of graphene with a nonlinear absorption coefficient, $beta$, of ~2 to 9x10^-8 cm/W. Two distinct time scales associated with the relaxation of photoexcited carriers, a fast one in the range of 130-330 fs (related to carrier-carrier scattering) followed by a slower one in 3.5-4.9 ps range (associated with carrier-phonon scattering) are observed.Comment: 3 pages, 2 figures, 2 table

Differential amplification of rDNA repeats in barley translocation and duplication lines: role of a specific segment

Variation in restriction pattern, relative amounts of the two ribosomal DNA (rDNA) repeats, and the overall content of rDNA were compared among twelve segmental duplications and eleven parental translocations involving NOR6 and NOR7 of cultivated barley. Southern blot hybridization revealed two rDNA repeats of 9.9 kb and 9.0 kb. While all duplications snowed dimers for these rDNA repeats, the duplication lines D29 and D47 displayed trimers in addition to a higher proportion of rDNA repeats as dimers. The rDNA of Dl, D29 and D47 showed resistance to Bam HI and Taq I digestion, indicating possible melhylation of cytosine and adenine. Densitometric scans of autoradiographs revealed variations in the relative amounts of the 9.0 kb and 9.9 kb rDNA repeats among different karyotypes. Dot blot hybridizations indicated variation in the overall rDNA content. Comparison of the 9.0/9.9 kb ratios and the percentage of genomic DNA hybridizing to an rDNA clone of barley illustrates differential amplification for the two rDNA repeats. When the segmental composition of these deviating lines were compared, it was evident that the relative position of the segment 12-16 of chromosome 6 determines differential amplification while duplication of the same segment controls the overall rDNA content

Studies on the Geology and Beneficiation of Chandak Magne-site Deposit from Pithoragarh District, Uttar Pradesh

Stringent operating conditions in modern steel making furnaces demand high quality basic refractories based on magnesia. Source of good quality natural magnesite cont-ains considerable amounts of SiO2 and fluxing agents. Therefore, appropriate measures are to be taken to ensure the availablity of good quality magnesite. Measures for meeting the demand of quality magnesite are follows:- i) Upgrading of the presently available natural magnesite by various beneficiation techniques ; ii) Production of high quality magnesia from sea water

Quenching of fluorescence of aromatic molecules by graphene due to electron transfer

Investigations on the fluorescence quenching of graphene have been carried out with two organic donor molecules, pyrene butanaoic acid succinimidyl ester (PyBS, I) and oligo(p-phenylenevinylene) methyl ester (OPV-ester, II). Absorption and photoluminescence spectra of I and II recorded in mixture with increasing the concentrations of graphene showed no change in the former, but remarkable quenching of fluorescence. The property of graphene to quench fluorescence of these aromatic molecules is shown to be associated with photo-induced electron transfer, on the basis of fluorescence decay and time-resolved transient absorption spectroscopic measurements.Comment: 18 pages, 6 figure

Synthetic Aspects and Selected Properties of Graphene

Graphene has generated great sensation owing to its fascinating properties with possible potential applications. This two‐dimensional material exhibits half‐ integer quantum Hall effect and an ambipolar electric field effect, along with ballistic conduction of charge carriers. In this article, we provide a overview on some aspects of graphene devoting the special attention to synthesis, functionalization, self‐assembly, surface properties, gas adsorption and fluorescence quenching ability of graphene. Graphenes with varying number of layers can be synthesized by using different strategies. Graphene can be functionalized by different means in order to disperse it in various solvents. We also present the self‐assembly of graphene at the liquid‐liquid interface besides its surface properties including adsorption of hydrogen, carbon dioxide and methane. The remarkable property of graphene of quenching fluorescence of aromatic molecules is shown to be associated with photo‐induced electron transfe

Ultrastructural and molecular characterization of altered plastids in nuclear gene controlled yellow stripe mutant of Pennisetum americanum

The ultrastructural and molecular biological studies were conducted to elucidate the changes in the nuclear gene controlled plastid alterations in yellow stripe mutant of Pennisetum americanum. The plastids in yellow tissue were bound by a double membrane envelope and no internal thylakoid membrane differentiation, whereas plastid development was normal in the green tissue. The nuclear gene apparently influences the individual plastids as evidenced by the presence of heteroplastidic cells. Ribosomal RNAs were extracted from green and yellow seedlings with homozygous recessive and heterozygous genotypes. Plastid specific 23S and 16S rRNAs were absent in the yellow seedlings irrespective of the genotype. The presence of disorganized lamellar membranes in the rRNA/ribosome deficient plastids indicate that they are synthesized outside the plastid compartment. Restriction endonuclease analysis revealed no detectable differences in fragmentation pattern of the plastid DNAs from green and reverted green seedlings. This is consistent with the suggestion that the nuclear gene is not inducing any change in the plastid genome size and in the restriction enzyme recognition sites

Proceedings of the Fifth Regional Groundnut Workshop for Southern Africa 9-12 March 1992

Eighteen scientists representing national programs and agricultural universities in the Southern African Development Coordination Conference (SADCC) region participated in this regional workshop. Angola and Lesotho were the only countries of the region not represented. Also participating were five groundnut scientists from four other African countries(Ethiopia, Kenya, Nigeria, and Uganda), representatives from the Southern African Centre for Cooperation in Agricultural Research and Training(SACCAR) and Deutsche Gesellschaft fur Technische Zusammenarbeit(GTZ), and 10 ICRISAT delegates. Papers reviewed various aspects of groundnut research, particularly agronomy and physiology. Country reports summarized the state of groundnut research in each country represented. The recommendations made at the Workshop's plenary session provide valuable guidelines for regional project activities