Genetica

Polyploid origin, genetic diversity and population structure in the tetraploid sea lavender Limonium narbonense Miller (Plumbaginaceae) from eastern Spain.

Publication Date: 2012 Feb 2 PMID: 22297901
Authors: Palop-Esteban, M. - Segarra-Moragues, J. G. - Gonzalez-Candelas, F.
Journal: Genetica

Limonium narbonense Miller is a fertile tetraploid species with a sporophytic self-incompatibility system. This sea lavender is found in coastal salt marshes which have been under intense human pressure during the past decades resulting in significant habitat fragmentation. Eleven microsatellite loci specifically designed for this species were amplified in 135 individuals from five populations. These markers were used to investigate the polyploid nature, the levels of genetic diversity and population structure in this species. L. narbonense showed high levels of genetic diversity (A = 7.82, P = 100% H (T) = 0.446), consistent with its likely autotetraploid origin revealed in this study and obligate outcrossing breeding system. Inbreeding (F (IS)) values were low in the three southern populations (mean F (IS) = 0.062), and higher in the northern populations (mean F (IS) = 0.184). Bayesian analysis of population structure revealed that populations could be grouped into two genetic clusters, one including three southern populations and the other the two northernmost ones. Individuals from the two northernmost populations showed higher admixture of the two genetic clusters than individuals from the three southern ones. A thorough analysis of microsatellite electrophoretic patterns suggests an autotetraploid origin for L. narbonense. The genetic structure revealed in this study is attributed to a recent migration from the southern area. This result suggests a net gene flow from the south to the north, likely facilitated by migratory movements of birds visiting the temporary flooded ponds occupied by L. narbonense.

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Characterization of barley Prp1 gene and its expression during seed development and under abiotic stress.

Publication Date: 2012 Jan 31 PMID: 22290495
Authors: Jiang, Q. T. - Liu, T. - Ma, J. - Wei, Y. M. - Lu, Z. X. - Lan, X. J. - Dai, S. F. - Zheng, Y. L.
Journal: Genetica

The pre-mRNA processing (Prp1) gene encodes a spliceosomal protein. It was firstly identified in fission yeast and plays a regular role during spliceosome activation and cell cycle. Plant Prp1 genes have only been identified from rice, Sorghum and Arabidopsis thaliana. In this study, we reported the identification and isolation of a novel Prp1 gene from barley, and further explored its expressional pattern by using real-time quantitative RT-PCR, promoter prediction and analysis of microarray data. The putative barley Prp1 protein has a similar primary structure features to those of other known Prp1 protein in this family. The results of amino acid comparison indicated that Prp1 protein of barley and other plant species has a highly conserved 3' termnal region while their 5' sequences greatly varied. The results of expressional analysis revealed that the expression level of barley Prp1 gene is always stable in different vegetative tissues, except it is up-regulated at the mid- and late stages of seed development or under the condition of cold stress. This kind of expressional pattern for barley Prp1 is also supported by our results of comparison of microarray data from barley, rice and Arabidopsis. For the molecular mechanism of its expressional pattern, we conclude that the expression of Prp1 gene may be up-regulated by the increase of pre-mRNAs and not be constitutive or ubiquitous.

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Genomic content and new insights on the origin of the B chromosome of the cichlid fish Astatotilapia latifasciata.

Publication Date: 2012 Jan 29 PMID: 22286964
Authors: Fantinatti, B. E. - Mazzuchelli, J. - Valente, G. T. - Cabral-de-Mello, D. C. - Martins, C.
Journal: Genetica

B chromosomes are additional chromosomes widely studied in a diversity of eukaryotic groups, including fungi, plants and animals, but their origin, evolution and possible functions are not clearly understood. To further understand the genomic content and the evolutionary history of B chromosomes, classical and molecular cytogenetic analyses were conducted in the cichlid fish Astatotilapia latifasciata, which harbor 1-2 B chromosomes. Through cytogenetic mapping of several probes, including transposable elements, rRNA genes, a repeated DNA genomic fraction (C (0) t - 1 DNA), whole genome probes (comparative genomic hybridization), and BAC clones from Oreochromis niloticus, we found similarities between the B chromosome and the 1st chromosome pair and chromosomes harboring rRNA genes. Based on the cytogenetic mapping data, we suggest the B chromosome may have evolved from a small chromosomal fragment followed by the invasion of the proto-B chromosome by several repeated DNA families.

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Patterns of spatial genetic structuring in the endangered limpet Patella ferruginea: implications for the conservation of a Mediterranean endemic.

Publication Date: 2012 Jan 28 PMID: 22286933
Authors: Casu, M. - Rivera-Ingraham, G. A. - Cossu, P. - Lai, T. - Sanna, D. - Dedola, G. L. - Sussarellu, R. - Sella, G. - Cristo, B. - Curini-Galletti, M. - Garcia-Gomez, J. C. - Espinosa, F.
Journal: Genetica

Patella ferruginea Gmelin, 1791 is an endangered marine gastropod endemic to the Western Mediterranean. Its range is restricted to the Sardinian-Corsican region (SCR), North Africa, a few scattered sites in Southern Spain, and Sicily. Inter-simple sequence repeat (ISSR) markers and three different mitochondrial DNA (mtDNA) regions, Cytochrome c Oxidase subunit I, 12S (small-subunit ribosomal RNA gene) and 16S (large-subunit ribosomal RNA gene), were used to investigate the presence of genetic population structuring. The mtDNA sequences showed very low levels of genetic differentiation. Conversely, ISSRs showed the presence of two main genetic groups, corresponding to Spain, North Africa and Sicily and the SCR. The SCR was further split into two subgroups. The ISSR results suggest that, on a regional scale, the genetic structure of P. ferruginea is mainly determined by the restriction of gene flow by dispersal barriers. On a more local scale human harvesting may play a crucial role in population structuring by increasing the effect of genetic drift.

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Nucleotide sequence and chromosomal localization of the gene for pierisin-1, a DNA ADP-ribosylating protein, in the cabbage butterfly Pieris rapae.

Publication Date: 2012 Jan 12 PMID: 22237414
Authors: Yamamoto, M. - Takahashi-Nakaguchi, A. - Matsushima-Hibiya, Y. - Nakano, T. - Totsuka, Y. - Imanishi, S. - Mitsuhashi, J. - Watanabe, M. - Nakagama, H. - Sugimura, T. - Wakabayashi, K.
Journal: Genetica

Cabbage butterfly, Pieris rapae, contains a unique DNA ADP-ribosylating protein, pierisin-1, which transfers ADP-ribose moiety of NAD to guanine bases of DNA. Pierisin-like proteins are only distributed in subtribes Pierina, Aporiina and Appiadina of the family Pieridae. In this study, we obtained genomic clones carrying the pierisin-1 gene from adult samples of P. rapae by plaque hybridization. The pierisin-1 gene was found to consist of two exons, 0.1-kb exon 1 and 3.9-kb exon 2, and a 2.3-kb intron. In addition, we could demonstrate that the putative promoter in the about 3-kb upstream region from the transcription start site of the gene include a transcriptional activating motif involved in immune pathways and hormonal regulation. We also examined chromosomal localization of the pierisin-1 gene. Fluorescence in situ hybridization (FISH) analysis using Cy3-labeled pierisin-1 genomic clone demonstrated the localization of the gene near the kinetochore in chromosome 9. Thus, we confirmed that the pierisin-1 gene is located in the genome of P. rapae.

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Genetic structure of traditional varieties of bitter manioc in three soils in Central Amazonia.

Publication Date: 2012 Jan 7 PMID: 22228136
Authors: Alves-Pereira, A. - Peroni, N. - Abreu, A. G. - Gribel, R. - Clement, C. R.
Journal: Genetica

Manioc is the most important food crop that originated in Amazonia. Many studies have increased our understanding of its evolutionary dynamics under cultivation. However, most of them focused on manioc cultivation in environments with low soil fertility, generally Oxisols. Recent ethnobotanical observations showed that bitter manioc also performs well in high fertility soils, such as Amazonian dark earths (ADE) and the floodplain. We used 10 microsatellite loci to investigate the genetic diversity and structure of bitter manioc varieties grown in different soil types in communities of smallholder farmers along the middle Madeira River in Central Amazonia. The genetic diversity of some sweet varieties and seedlings was also evaluated. Adult individuals showed higher levels of genetic diversity and smaller inbreeding coefficients (A ( R ) = 5.52, H ( O ) = 0.576, f = 0.086) than seedlings (A ( R ) = 4.39, H ( O ) = 0.421, f = 0.242). Bitter manioc varieties from the floodplain showed higher levels of genetic diversity (A ( R ) = 5.19, H ( O ) = 0.606) than those from ADE (A ( R ) = 4.45, H ( O ) = 0.538) and from Oxisols (A ( R ) = 4.15, H ( O ) = 0.559). The varieties grown in the floodplain were strongly differentiated from the varieties grown in Oxisols (F ( ST ) = 0.093) and ADE (F ( ST ) = 0.108), suggesting important genetic structuring among varieties grown in the floodplain and upland soils (ADE and Oxisols). This is the first time that genetic divergence of bitter manioc varieties in cultivation in different Amazonian soils in a small geographic area is reported.

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Genetic variation in a female genital trait evolved by sexual coevolution.

Publication Date: 2012 Jan 5 PMID: 22219041
Authors: Jimenez Ambriz, G. - Mota, D. - Cordero, C.
Journal: Genetica

Understanding the patterns of genetic variation of traits subject to sexual selection is fundamental for explaining its evolutionary dynamics and potential for sexual coevolution. The signa of female Lepidoptera are sclerotized structures located on the inner surface of the genital receptacle that receives the spermatophore during copulation (the corpus bursae), whose main function is tearing the spermatophore envelope. Comparative data indicate that the evolution of signa has been influenced by sexually antagonistic coevolution with spermatophore envelopes. We looked for additive genetic variation in the size and shape of signa in females of the butterfly Callophrys xami (Lycaenidae) from two localities (BG and FC) in Mexico City. We also looked for genetic variation in female body size and in the size of corpus bursae. There were significant between-population differences in female body size, signa width and three signa shape traits. We found significant extranuclear maternal effects in one component of signa shape in the BG population, and in body weight, signa length and in one uniform component of signa shape in the FC population. Extranuclear maternal contributions could permit the evolution of female adaptations even if these reduce male fitness. We found additive genetic variation in signa length and width only in one population (BG); heritability estimates were high: 0.96 and 0.8, respectively. The existence of additive genetic variation in signa size could be, at least in part, a result of relaxed sexually antagonistic selection pressures due to the low level of polyandry exhibited by this species. Our results imply that there is currently potential for further sexual coevolution in this trait.

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