Untersuchungen zur genetischen Variabilität in einer Kreuzungspopulation von Labormäusen

Two high fecundity mouse lines, FL1 and FL2, were established after a long-term selection for increased litter size. In order to identify potential candidate genes for litter size an advanced intercross mouse population (AIL) was established as a crossbred between FL1 and a particular control line. A coarse QTL-mapping analysis was conducted in the F2-generation of this population. In total 47 genome-wide significant (5%) QTL were identified for 31 different traits. QTL for litter size, litter weight and body mass traits were mainly identified on chromosomes 2, 4, 9 and 13, on chromosomes 2, 4, 7 and 8 and on chromosomes 2, 4 and 13 respectively. This study verified the existence of the potential candidate genes with larger effect for litter size and emphasized several chromosomes to which more attentions should be paid in subsequent fine-mapping. A new method was developed to construct a modified relationship matrix for AIL-crossbreds that makes use of founder allele frequencies for markers and the pedigree. Thereby founder relationships were deduced from about 140k biallelic marker loci. This relationship matrix was derived both for autosomal and X-chromosomal loci and may be useful in the context of analyses of selection experiments. Real application was demonstrated with data from 30 generations of the AIL population, comprising about 19000 pedigreed animals. By applying the newly derived relationship matrices litter size-related traits and body mass related traits from the AIL were more deeply analyzed. Thereby X-chromosomal genetic variation for body mass traits was not found to be significant, in agreement with no significant X-chromosomal QTL in the coarse mapping study. Both the results from coarse mapping and quantitative analyses suggest that it is worthwhile to further fine-map the already coarsely mapped QTL, especially for litter size and litter weight.Zwei Mauslinien mit hoher Fruchtbarkeit, FL1 und FL2, wurden mittels Langzeitselektion auf eine größere Wurfgröße etabliert. Um potenzielle Kandidatengene für die Wurfgröße zu identifizieren, wurde eine fortgeschrittene Intercross-Linie (AIL) als Kreuzung zwischen FL1 und einer eigenen Kontrolllinie erstellt. Eine grobe QTL-Kartierung wurde in der F2-Generation dieser Population durchgeführt. Insgesamt wurden 47 genomweit signifikante (p< 5%) QTL für 31 verschiedene Merkmale identifiziert. QTL für Wurfgröße, Wurfgewicht und Körpermasse wurden hauptsächlich auf den Chromosomen 2, 4, 9 und 13, auf den Chromosomen 2, 4, 7 und 8 sowie auf den Chromosomen 2, 4 und 13 identifiziert. Damit bestätigte sich die Existenz potenzieller Kandidatengene mit größerem Effekt auf die Wurfgröße. Eine neue Methode wurde entwickelt, um eine modifizierte Verwandtschaftsmatrix für AIL-Kreuzungen aufzustellen, die die Markerallelfrequenzen der Gründertiere und das Pedigree aller Nachkommen berücksichtigt. Die Verwandtschaft zwischen Gründertieren wurde aus ca. 140k biallelen Marker-Loci abgeleitet. Diese Verwandtschaftsmatrix wurde sowohl für autosomale als auch für X-chromosomale Loci aufgestellt und ist allgemein für die Auswertung von Selektionsexperimenten von Nutzen. Als Anwendungsbeispiel wurden Daten von 30 Generationen der AIL-Population ausgewertet, wobei rund 19000 tiere im Pedigree enthalten waren. Merkmale der Wurfgröße und der Körpermasse in der AIL wurden anschließend eingehender analysiert, wobei die neuartigen Verwandtschftsmatrizen eingestzt wurden. Im Ergebnis war X-chromosomale genetische Variation für Merkmale der Körpermasse nicht signifikant, in Übereinstimmung mit fehlenden X-chromosomalen QTL in der Grobkartierungsstudie. Sowohl die Ergebnisse der Grobkartierung als auch die quantitativen Analysen deuten darauf hin, dass es sich lohnt, die Positionen der bereits grob kartierten QTL weiter zu verfeinern, insbesondere für Wurfgröße und Wurfgewicht

Chromosomal instability in Streptomyces avermitilis: major deletion in the central region and stable circularized chromosome

<p>Abstract</p> <p>Background</p> <p>The chromosome of <it>Streptomyces </it>has been shown to be unstable, frequently undergoing gross chromosomal rearrangements. However, the mechanisms underlying this phenomenon remain unclear, with previous studies focused on two chromosomal ends as targets for rearrangements. Here we investigated chromosomal instability of <it>Streptomyces avermitilis</it>, an important producer of avermectins, and characterized four gross chromosomal rearrangement events, including a major deletion in the central region. The present findings provide a valuable contribution to the mechanistic study of genetic instability in <it>Streptomyces</it>.</p> <p>Results</p> <p>Thirty randomly-selected "bald" mutants derived from the wild-type strain all contained gross chromosomal rearrangements of various types. One of the bald mutants, SA1-8, had the same linear chromosomal structure as the high avermectin-producing mutant 76-9. Chromosomes of both strains displayed at least three independent chromosomal rearrangements, including chromosomal arm replacement to form new 88-kb terminal inverted repeats (TIRs), and two major deletions. One of the deletions eliminated the 36-kb central region of the chromosome, but surprisingly did not affect viability of the cells. The other deletion (74-kb) was internal to the right chromosomal arm. The chromosome of another bald mutant, SA1-6, was circularized with deletions at both ends. No obvious homology was found in all fusion sequences. Generational stability analysis showed that the chromosomal structure of SA1-8 and SA1-6 was stable.</p> <p>Conclusions</p> <p>Various chromosomal rearrangements, including chromosomal arm replacement, interstitial deletions and chromosomal circularization, occurred in <it>S. avermitilis </it>by non-homologous recombination. The finding of an inner deletion involving in the central region of <it>S. avermitilis </it>chromosome suggests that the entire <it>Streptomyces </it>chromosome may be the target for rearrangements, which are not limited, as previously reported, to the two chromosomal ends.</p

Organic Peroxide-Sensing Repressor OhrR Regulates Organic Hydroperoxide Stress Resistance and Avermectin Production in Streptomyces avermitilis

The bacterium Streptomyces avermitilis is an industrial-scale producer of avermectins, which are important anthelmintic agents widely used in agriculture, veterinary medicine, and human medicine. During the avermectin fermentation process, S. avermitilis is exposed to organic peroxides generated by aerobic respiration. We investigated the role of MarR-family transcriptional regulator OhrR in oxidative stress response and avermectin production in S. avermitilis. The S. avermitilis genome encodes two organic hydroperoxide resistance proteins: OhrB1 and OhrB2. OhrB2 is the major resistance protein in organic peroxide stress responses. In the absence of organic peroxide, the reduced form of OhrR represses the expression of ohrB2 gene by binding to the OhrR box in the promoter region. In the presence of organic peroxide, the oxidized form of OhrR dissociates from the OhrR box and the expression of ohrB2 is increased by derepression. OhrR also acts as a repressor to regulate its own expression. An ohrR-deletion mutant (termed DohrR) displayed enhanced avermectin production. Our findings demonstrate that OhrR in S. avermitilis represses avermectin production by regulating the expression of pathway-specific regulatory gene aveR. OhrR also plays a regulatory role in glycolysis and the pentose phosphate (PP) pathway by negatively controlling the expression of pykA2 and ctaB/tkt2-tal2-zwf2-opcA2-pgl

α-Lys424 Participates in Insertion of FeMoco to MoFe Protein and Maintains Nitrogenase Activity in Klebsiella oxytoca M5al

Our previous investigation of substrates reduction catalyzed by nitrogenase suggested that α-Ile423 of MoFe protein possibly functions as an electron transfer gate to Mo site of active center-“FeMoco”. Amino acid residue α-Lys424 connects directly to α-Ile423, and they are located in the same α-helix (α423-431). In the present study, function of α-Lys424 was investigated by replacing it with Arg (alkaline, like Lys), Gln (neutral), Glu (acidic), and Ala (neutral) through site-directed mutagenesis and homologous recombination. The mutants were, respectively, termed 424R, 424Q, 424E, and 424A. Studies of diazotrophic cell growth, cytological, and enzymatic properties indicated that none of the substitutions altered the secondary structure of MoFe protein, or normal expression of nifA, nifL, and nifD. Substitution of alkaline amino acid (i.e., 424R) maintained acetylene (C2H2) and proton (H+) reduction activities at normal levels similar to that of wild-type (WT), because its FeMoco content did not reduce. In contrast, substitution of acidic or neutral amino acid (i.e., 424Q, 424E, 424A) impaired the catalytic activity of nitrogenase to varying degrees. Combination of MoFe protein structural simulation and the results of a series of experiments, the function of α-Lys424 in ensuring insertion of FeMoco to MoFe protein was further confirmed, and the contribution of α-Lys424 in maintaining low potential of the microenvironment causing efficient catalytic activity of nitrogenase was demonstrated

Графический дизайн как визуальный язык межкультурного взаимодействия

This article describes how visual graphics language as a sign system can be in contact with the audience, overcoming the language barrier. In terms of graphic design it can be available to transfer information, and even affect the viewer, causing artistic and emotional reflection.Эта статья о том, как визуальный язык графики в виде знаковой символики может входить в контакт со зрителем, преодолевая языковый барьер. На языке графического дизайна можно доступно передать информацию и даже воздействовать на зрителя, вызывая при этом художественно-эмоциональные образы

Population response of intestinal microbiota to acute Vibrio alginolyticus infection in half-smooth tongue sole (Cynoglossus semilaevis)

IntroductionVibriosis causes enormous economic losses of marine fish. The present study investigated the intestinal microbial response to acute infection of half-smooth tongue sole with different-dose Vibrio alginolyticus within 72 h by metagenomic sequencing.MethodsThe inoculation amount of V. alginolyticus for the control, low-dose, moderate-dose, and high-dose groups were 0, 8.5 × 101, 8.5 × 104, and 8.5 × 107 cells/g respectively, the infected fish were farmed in an automatic seawater circulation system under a relatively stable temperature, dissolved oxygen and photoperiod, and 3 ~ 6 intestinal samples per group with high-quality DNA assay were used for metagenomics analysis.ResultsThe acute infections with V. alginolyticus at high, medium, and low doses caused the change of different-type leukocytes at 24 h, whereas the joint action of monocytes and neutrophils to cope with the pathogen infection only occurred in the high-dose group at 72 h. The metagenomic results suggest that a high-dose V. alginolyticus infection can significantly alter the intestinal microbiota, decrease the microbial α-diversity, and increase the bacteria from Vibrio and Shewanella, including various potential pathogens at 24 h. High-abundance species of potential pathogens such as V. harveyii, V. parahaemolyticus, V. cholerae, V. vulnificus, and V. scophthalmi exhibited significant positive correlations with V. alginolyticus. The function analysis revealed that the high-dose inflection group could increase the genes closely related to pathogen infection, involved in cell motility, cell wall/ membrane/envelope biogenesis, material transport and metabolism, and the pathways of quorum sensing, biofilm formation, flagellar assembly, bacterial chemotaxis, virulence factors and antibiotic resistances mainly from Vibrios within 72 h.DiscussionIt indicates that the half-smooth tongue sole is highly likely to be a secondary infection with intestinal potential pathogens, especially species from Vibrio and that the disease could become even more complicated because of the accumulation and transfer of antibiotic-resistance genes in intestinal bacteria during the process of V. alginolyticus intensified infection

Foreign Direct Investment in Electronic Industry in SouthEeast Asia

Since its independence after World War II, Southeast Asia has achieved a lot of economic development and attracted many FDI. The development of its electronics industry has also made considerable achievements, and international electronics giants currently favor it. However, although many international electronics giants are increasing investment in Southeast Asia now, the future of investment in the electronics industry in Southeast Asia may not be smooth sailing. Southeast Asian countries need to make more efforts to attract more investment from foreign electronics giants.Since its independence after World War II, Southeast Asia has achieved a lot of economic development and attracted many FDI. The development of its electronics industry has also made considerable achievements, and international electronics giants currently favor it. However, although many international electronics giants are increasing investment in Southeast Asia now, the future of investment in the electronics industry in Southeast Asia may not be smooth sailing. Southeast Asian countries need to make more efforts to attract more investment from foreign electronics giants