Journal of Genetics

A study was conducted to examine the genetic divergence and to determine the genetic loci and genes associated with natural variation of grain zinc (Zn) concentration among 28 landraces, improved varieties and advanced breeding lines of rice using candidate gene specific primers. Field evaluation of the experimental material was conducted in randomized block design with three replications and Zn content in unpolished grains of the entries was determined by addition of nitric acid and perchloric acid (1:3) following the procedure of diacid digestion method. Statistical analysis revealed the exploitable extent of variability with respect to grain Zn concentration among the entries. Eighteen entries were selected from the two extremes of grain Zn distribution range and subjected to molecular profiling using a panel of 14 candidate genes specific 12 reported and 14 designed primer pairs. Only eight (OsZIP1-1, OsZIP3a, OsZIP4a, OsZIP5-3, OsZIP7-2, OsZIP8b, OsNRAMP7 and OsNAAT1) reported and eight (OsZIP3K, OsZIP4K, OsZIP5K, OsZIP7K, OsNRAMP7K, OsNAAT1K, OsNACK and OsYSL14K) designed primers generated polymorphic amplified products showing sequence length variation due to targeted amplification of candidate genes specific genomic regions. Ample genetic differentiation and divergence were revealed among the entries, which were accommodated into similarity coefficient-based six clusters, remarkably consistent with grain Zn concentration of the entries. Hierarchical classification pattern of entries was almost completely corroborated by principal co-ordinate analysis-based spatial distribution pattern of their genetic profiles. Molecular analysis based on candidate genes specific primers appeared to be an efficient approach for the elucidation of genetic differentiation and divergence in relation to variation of grain Zn concentration among entries. Hence, these markers can be effectively and efficiently utilized for grain Zn concentration related discrimination of rice genotypes and selection of parental genotypes for grain Zn biofortification. Microsatellites were detected within the candidate genes and amplicons, thereby providing a basis to deduce that the repeat sequence length variation in candidate genes may be a role player in the differential grain Zn accumulation in rice varieties. Single marker analysis established the association of OsNACK, OsZIP1-1, OsNRAMP7 and OsNRAMP7K with grain Zn concentration. Thus, these four markers can be effectively used in marker-assisted selection programme for grain Zn biofortification in rice.

Consanguineous marriages have been favoured throughout South India for many generations. On theoretical grounds it was proposed that long-term inbreeding would have resulted in the elimination of deleterious, recessive lethal and sub-lethal genes. As part of a newborn screening programme for amino acidopathies, data were collected on the level of inbreeding in the current populations of the cities of Bangalore and Mysore, and on the relationship between consanguinity and mean numbers of liveborn and living children. Mean cnonsanguinity was 32.24%, equivalent to a cuoefficient of inbreeding in the newborns,F = 00271. There were no significant differences between the various inbreeding classes in the number of liveborn or living children, nor was a significant consanguinity-related effect on the proportion of survivors detectable. In the light of these findings, the effects on the gene pool of multiple generations of inbreeding are discussed.

Genes that code for proteins expressed at high and low levels in plants were classified into separate data sets. The two data sets were analysed to identify the conserved nucleotide sequences that may characterize genes with contrasting levels of expression. The AUG context that characterized the highly expressed genes is (A/C)N2AAN3(A/T)T(A/C) AACAATGGCTNCC(T/A)CNA(C/T)(A/C). The data set of highly expressed genes shows overrepresentation of codons for alanine at the second position and serine at the third and fourth positions after the translation initiation codon. The characteristic transcription initiation site in the highly expressed genes is CAN(A/C)(A/C)(C/A)C(C/A)N2A(C/A). The promoter region is characterized by two tandemly repeated TATA elements, sometimes with one and rarely with two point mutations in the highly expressed genes. Besides the two tandemly repeated TATA elements, the promoter context in the highly expressed genes is overrepresented by C, C and G at the -3, -1 and+9 positions respectively. The characteristic TATA motif in the highly expressed plant genes is (T/C)(T/A)N2TCACTATATATAG. Most of these features are not present in the genes ubiquitously expressed at low levels in plants.

Data for body length, depth, width, fore cannon length, fold score and mutton score were collected on two groups of Peppin Merino ewe lambs. The experimental animals comprised 284 ewe lambs born in the spring of 1951 (group ‘A’) and 273 born in the autumn of 1952 (group ‘W’) at the Trangie Agricultural Experiment Station of the New South Wales Department of Agriculture. The estimates for heritability calculated by the method of intra-sire correlation for body depth, length, width, fore cannon length, fold score and mutton score are: 0.00, 0.00, 0.08, 0.16, 0.28 and 0.28 respectively in group ‘W’ and 0.29, 0.10, 0.48, 0.30, 0.79 and 0.10 in group ‘A’ and 0.01, 0.00, 0.27, 0.24, 0.46 and 0.13 in the combined groups (A & W). Estimate for fold score calculated by sire-offspring regression for both the groups is 0.34.

A mosaic black-blue and white Dutch rabbit is reported. The condition was not transmitted to any of his 144 offspring. The possibility of the presence of genes controlling pigmentation in normally white areas is discussed, as also is the tendency for somatic instability being increased through inbreeding.