Hereditas最新文献

In this study part of the mitochondrial D-loop was sequenced in a total of 40 samples from nine Swedish local chicken breeds. Among our 40 samples we observed 15 segregating sites and seven different haplotypes. The most common haplotype was present in all investigated individuals in five breeds and together with other haplotypes in three breeds. This haplotype is common in domestic chickens and has been found in both local and commercial breeds in many parts of the world. The breed Ölandshöna was most different from the other Swedish breeds with all three individuals sharing a haplotype that differed from the most common haplotype at nine of the 15 segregating sites.

MicroRNAs (miRNAs) are approximately 21 nt noncoding RNAs that influence the phenotypes of different species through the post-transcriptional regulation of gene expression. Although many miRNAs have been identified in a few model plants, less is known about miRNAs specific to cucumber (Cucumis sativus L.). In this study, two libraries of cucumber RNA, one based on fruit samples and another based on mixed samples from leaves, stems, and roots, were prepared for deep-sequencing. A total of 110 sequences were matched to known miRNAs in 47 families, while 56 sequences in 46 families are newly identified in cucumber. Of these, 77 known and 44 new miRNAs were differentially expressed, with a fold-change of at least 2 and p-value < 0.05. In addition, we predicted the potential targets of known and new miRNAs. The identification and characterization of known and new miRNAs will enable us to better understand the role of these miRNAs in the formation of cucumber fruit.

In 1928, the Swedish geneticists Hermann Nilsson-Ehle and Åke Gustafsson started on their suggestion experiments with induced mutations using the barley crop. In 1953, at the instigation of the Swedish Government, the ‘Group for Theoretical and Applied Mutation Research’ was established. Its aim was to study basic research problems in order to influence and improve methods for breeding cultivated plants. The research was non-commercial, even if some mutants were of practical importance. The peaks of activities occurred during the 1950s, 1960s and 1970s. Applying X-rays and UV-irradiation very soon the first chlorophyll mutations were obtained followed by the first viable mutations ‘Erectoides’. Soon the X-ray experiments expanded with other types of irradiation such as neutrons etc. and finally with chemical mutagens, starting with mustard gas and concluding with the sodium azide. The research brought a wealth of observations of general biological importance, high increased mutation frequencies, difference in the mutation spectrum and to direct mutagenesis for specific genes. A rather large collection of morphological and physiological mutations, about 12 000 different mutant alleles, with a very broad variation were collected and incorporated into the Nordic Genetic Resource Center (NordGen) Sweden. Barley, the main experimental crop has become one of the few higher plants in which biochemical genetics and molecular biological studies are now feasible. The collection is an outstanding material for mapping genes and investigating the barley genome. Several characters have been studied and analyzed in more detail and are presented in this historical review.

Gunnar Östergren (1918–1998), a cytologist-geneticist of rank (Fig. 1), was active at the Inst. of Genetics, Univ. of Lund (Sweden) during the years 1940–1964, intermitted by a stay in Stockholm (Nobel Institute, 1947–1951), and followed by being a professor of genetics, and later professor emeritus, at the Swedish Univ. of Agricultural Sciences in Uppsala (1964–1998). Gunnar Östergren (G.Ö.) had connections with HEREDITAS in two ways. Firstly, during the years at the Inst. of Genetics in Lund, where the editorial office of HEREDITAS was located, he assisted in the editorial work of this periodical by handling the pictorial material of accepted articles. This task was handed over to me when he left for Uppsala, after giving me useful guidelines that I made use of during my years at this post. Secondly, HEREDITAS was the forum where he published the majority of his work. His most cited publication is his PhD thesis on chromosome orientation during cell division (Östergren 1951), briefly highlighted here. This work laid the grounds for, and was ratified by, recent findings.

In addition to these connections to HEREDITAS that motivated me to write about G.Ö. is the fact that he has been my supervisor and mentor during the time I worked for my PhD degree (1958–1963). My respect and admiration of G.Ö. is great.

The Mendelian Society in Lund was founded in 1910. The initiative came from two young biologists supported by a wide circle of interested plant breeders and academics. Already from the start the society was dominated by the towering personality Herman Nilsson-Ehle. After two active years, the Society went into temporal hibernation until it resumed its activities in spring 1916, when Nilsson-Ehle was on his way to become Sweden's first professor of genetics. One of the aims of the Society was to launch a scientific journal for local scientists directed at an international audience. After a successful fundraising campaign, Hereditas was started in 1920. One of the original instigators of the Mendelian Society, Robert Larsson, became its first editor, and he remained in this position for more than 30 years. Both he and Nilsson-Ehle were fascinating personalities, deeply rooted in their time's scientific and ideological debates.

The molecular structure of B chromosomes (Bs) is relatively well studied. Previous research demonstrates that Bs of various species usually contain two types of repetitive DNA sequences, satellite DNA and ribosomal DNA, but Bs also contain genes encoding histone proteins and many others. However, many questions remain regarding the origin and function of these chromosomes. Here, we focused on the comparative cytogenetic characteristics of the red fox and Chinese raccoon dog B chromosomes with particular attention to the distribution of repetitive DNA sequences and their methylation status. We confirmed that the small Bs of the red fox show a typical fluorescent telomeric distal signal, whereas medium-sized Bs of the Chinese raccoon dog were characterized by clusters of telomeric sequences along their length. We also found different DNA methylation patterns for the B chromosomes of both species. Therefore, we concluded that DNA methylation may maintain the transcriptional inactivation of DNA sequences localized to B chromosomes and may prevent genetic unbalancing and several negative phenotypic effects.

The genetic diversity of 23 chickpea accessions representing Kyrgyz landraces and cultivars, ICARDA breeding lines, Spanish and Turkish cultivars was characterized using nine microsatellite (SSR) markers which generated a total of 122 alleles. The number of alleles (Na) per locus varied from 9 to 20. The observed heterozygosity (Ho) ranged between 0.05 and 0.43 (average 0.13) whereas both the expected heterozygosity (He) and polymorphic information content (PIC) ranged from 0.71 to 0.90 (average 0.83). Analysis of molecular variance (AMOVA) showed that 62% of the total genetic variation was found within accessions while the remaining 38% was found among accessions. Principal coordinate analysis (PCoA) indicated the presence of two groups. The two Kyrgyz cultivars were found apart from these groups. Cluster analysis generally confirmed the results of PCoA and also separated the Kyrgyz cultivars from the subcluster formed by Kyrgyz landraces and the subclusters formed by breeding lines from ICARDA along with landraces from Turkey and Spain. In addition, protein content and mineral concentration were determined. Protein content and mineral concentrations for Ca, S, Mg, P, K, Fe, Mn, Cu and Zn varied significantly among accessions. The results show that Kyrgyz germplasm provides a source of diversity for improvement of chickpea.

Cellular differentiation during eumetazoan development is based on highly conserved signalling pathways. Two of them, the Notch and the EGFR signalling pathways, are closely intertwined. We have identified two potential target sites of the Mitogen activated kinase (MAPK), the downstream effector kinase of EGFR, within Hairless (H), the major antagonist of Notch signalling in Drosophila. Assuming that phosphorylation of these sites modulates H activity, a direct influence of EGFR signalling on Notch pathway regulation might be possible. This hypothesis was tested by generating a phospho-deficient and a phospho-mimetic H isoform and by assaying for their biological activity. We first addressed the binding of known H interaction partners Su(H), Gro, CtBP and Pros26.4 which was similar between mutant and wild type H. Next we assayed eye, wing and bristle development which are strongly affected by the overexpression of H due to the inhibition of Notch signalling. Overexpression of the mutant constructs resulted in phenotypes similar to wildtype H overexpression, yet with subtle differences in phenotypic severity. However, large variations suggest that the mutated residues may be critical for the overall structure or stability of H. Albeit of minor impact, EGFR may fine tune Notch signalling via MAPK dependent phosphorylation of H.

The genus Harpagophytum has two species: H. procumbens which is an important medicinal plant in southern Africa, and H. zeyheri. Genetic diversity in 96 samples, obtained by germinating seeds collected from Botswana, was assessed using six inter-simple sequence repeat (ISSR) and 10 random amplified polymorphic DNA (RAPD) primers. These DNA markers yielded a total of 138 polymorphic bands. Polymorphism information content (PIC) ranged from 0.06 to 0.39 for ISSR primers, and from 0.09 to 0.43 for RAPD primers. Jaccard's similarity coefficients were highest when seedlings derived from the same fruit capsule were compared, while seedlings from different fruits on the same plant had intermediate values. The lowest values were recorded among seedlings from different plants. These results were consistent with an outcrossing breeding system in Harpagophytum. Analysis of molecular variance revealed significant differentiation (P < 0.01) between taxonomic units within Harpagophytum. About 39% of the variability occurred between the two species, H. procumbens and H. zeyheri. Plants with an intermediate morphology, i.e. putative hybrids (PH), showed 21% differentiation when compared with H. procumbens ssp. procumbens (PP), and 19% when compared with H. procumbens ssp. transvaalense (PT) or with H. zeyheri (ZZ). In addition, a deviating variant of PT was identified, here termed ‘procumbens new variety’ (PN). PN showed only 9% differentiation when compared with PT, 22% when compared with PP or with PH, and 41% when compared with ZZ. Considerable differentiation between the two Harpagophytum species was revealed also by a cluster analysis. Introgression was, however, suggested by the intermediate position of the putative hybrid plants in a principal component analysis while inter-specific gene flow was shown by a Bayesian genetic structure analysis.