Zonal hierarchy of differentiation markers and nestin expression during oval cell mediated rat liver regeneration

Oval cells constitute a heterogeneous population of proliferating progenitors found in rat livers following carcinogenic treatment (2-acetylaminofluorene and 70% hepatectomy). The aim of this study was to investigate the cellular pattern of various differentiation and cell type markers in this model of liver regeneration. Immunophenotypic characterisation revealed at least two subtypes emerging from the portal field. First, a population of oval cells formed duct-like structures and expressed bile duct (CD49f) as well as hepatocytic markers (α-foetoprotein, CD26). Second, a population of non-ductular oval cells was detected between and distally from the ductules expressing the neural marker nestin and the haematopoietic marker Thy1. Following oval cell isolation, a subset of the nestin-positive cells was shown to co-express hepatocytic and epithelial markers (albumin, CD26, pancytokeratin) and could be clearly distinguished from anti-desmin reactive hepatic stellate cells. The gene expression profiles (RT-PCR) of isolated oval cells and oval cell liver tissue were found to be similar to foetal liver (ED14). The present results suggest that the two oval cell populations are organised in a zonal hierarchy with a marker gradient from the inner (displaying hepatocytic and biliary markers) to the outer zone (showing hepatocytic and extrahepatic progenitor markers) of the proliferating progeny clusters.     

A Polymerase Chain Reaction Screening Method for Rapid Detection of Microsatellites in Bacterial Artificial Chromosomes

Standard protocols aimed at identifying subclones of interest from bacterial artificial chromosomes (BACs) include the use of hybridization methods that are time consuming and often require the use of radioactive isotopes. Through our efforts to identify microsatellites in BACs from rainbow trout (Oncorhynchus mykiss) we have developed a nonradioactive polymerase chain reaction (PCR)-based screening technique to select microsatellites containing subclones for marker development. Two BACs were subcloned and screened by PCR using a vector-specific primer and a mix of microsatellite repeat primers. The subclones were then sequenced to evaluate the efficiency of the PCR screening method. Correlation between positive PCR amplification and presence of microsatellites varied between the two BACs (21.9% and 71.4%), but still a sufficient number of subclones were identified to enable design and optimization of microsatellite markers.     

Transformation of recalcitrant turfgrass cultivars through improvement of tissue culture and selection regime

Tissue culture techniques, medium composition, pH value and targeted tissues, agroinfection and co-culture conditions, selection process were optimized for efficient turfgrass transformation. A highly regenerable callus lines were produced in callus induction medium modified from N6 basal medium. Six-week-old calluses were cultured on Pre-regeneration medium I for 4 days and then subjected to Agrobacterium tumefaciens. After co-cultivation at 20±1 °C in a 16 h light/8 h darkness for 3 days, the calluses were cultured on non-selective Pre-regeneration medium II supplemented with 400 mg l⁻¹ l-cysteine for 7 days. Plantlets were regenerated on the Regeneration medium without selection pressure. A selection pressure was given to the regenerated plantlets when they were rooted on the Plantlet rooting medium. Roots appeared within 8–12 days in putative transformed plantlets. Resistant plants obtained were phenotypically normal and fully fertile. Chemical and molecular analyses confirmed that foreign genes were successfully introduced into the genome of perennial ryegrass or tall fescue. The transformation efficiency can attain 23.3% in perennial ryegrass.     

Genetic variation of ticks (Ixodes ricinus L.) in the Lithuanian and Norwegian populations

RAPD markers were used to measure the genetic diversity of 119 individuals of Ixodes ricinus collected from Lithuania and Norway. The samples were analysed within and also between the populations. We analysed 74 loci in each of 6 populations. Our results show high levels of diversity within the populations. The percentage of polymorphic loci of the six analysed populations: Birzai, Vilnius, Kretinga, Tjore, Kjosvik and Odderoya were 68.9%, 58.1%, 78.38%, 62.2%, 44.6% and 68.9%, respectively. The percentage of polymorphic loci in the Lithuanian populations was 93.2%, and in the Norwegian populations 81.08%. The genetic distance ranged from 0.019 to 0.079 within Norwegian populations and from 0.005 to 0.0967 within Lithuanian populations and between the countries from 0.022 to 0.146. The genetic variation of I. ricinus among Norwegian populations was lower than among Lithuanian populations. The highest part of genetic variation in I. ricinus ticks depends on variation within Kretinga (Lithuania) and Odderoya (Norway) populations situated in coastal areas where many migratory and sea birds are aggregated.     

黄三七(毛茛科)茎次生木质部导管穿孔板的研究

利用扫描电子显微镜对东亚特有植物黄三七（Souliea vaginata（Maxim.） Franch.）茎的次生木质部离析材料进行了观察,结果表明,黄三七茎次生木质部中的导管分子端壁上具网状穿孔板（麻黄式穿孔板）、梯状穿孔板、网状-梯状混合穿孔板、网状-梯状-单穿孔混合型穿孔板、梯状-单穿孔混合型穿孔板及单穿孔板,同时也观察到了端壁多穿孔板和侧壁穿孔板,并对不同类型穿孔板中纹孔膜的残留也进行了观察。其中,网状穿孔板、各种过渡类型的穿孔板均为毛茛科植物中首次报道。根据观察结果,对导管分子穿孔板的演化及黄三七属植物的系统位置进行了分析。     

Genetic diversity and origin of weedy rice (Oryza sativa f. spontanea) populations found in North-eastern China revealed by simple sequence repeat (SSR) markers

BACKGROUND AND AIMS: Weedy rice (Oryza sativa f. spontanea) is one of the most notorious weeds occurring in rice-planting areas worldwide. The objectives of this study are to determine the genetic diversity and differentiation of weedy rice populations from Liaoning Province in North-eastern China and to explore the possible origin of these weedy populations by comparing their genetic relationships with rice varieties (O. sativa) and wild rice (O. rufipogon) from different sources. METHODS: Simple sequence repeat (SSR) markers were used to estimate the genetic diversity of 30 weedy rice populations from Liaoning, each containing about 30 individuals, selected rice varieties and wild O. rufipogon. Genetic differentiation and the relationships of weedy rice populations were analysed using cluster analysis (UPGMA) and principle component analysis (PCA). KEY RESULTS: The overall genetic diversity of weedy rice populations from Liaoning was relatively high (H(e) = 0.313, I = 0.572), with about 35 % of the genetic variation found among regions. The Liaoning weedy rice populations were closely related to rice varieties from Liaoning and japonica varieties from other regions but distantly related to indica rice varieties and wild O. rufipogon. CONCLUSIONS: Weedy rice populations from Liaoning are considerably variable genetically and most probably originated from Liaoning rice varieties by mutation and intervarietal hybrids. Recent changes in farming practices and cultivation methods along with less weed management may have promoted the re-emergence and divergence of weedy rice in North-eastern China.     

The use of nuclear DNA molecular markers for studying speciation and systematics as exemplified by the “Lacerta agilis complex” (Sauria: Lacertidae)

Four types of nuclear DNA markers identified by the taxonprint, RAPD, and IMP (Inter-MIR-PCR) methods, and the nucleotide sequences of satellite DNA monomers have been used to analyze the molecular genetic similarity between some populations, subspecies, and species of lizards combined into the group Lacerta s. str., as well as representatives of some other genera. The notions on the systematics and phylogeny of this group based on morphological and zoogeographic criteria have been compared to the conclusions based on molecular genetic data. The genus and species subdivisions of populations based on nuclear molecular markers and morphological characters generally agree with each other, the degree of genetic differences being correlated with the taxonomy suggested by zoomorphologists. The degree of differences between the subspecies of one of the species studied, Lacerta agilis, varies depending on the molecular markers used: according to the results of RAPD analysis, all subspecies substantially differ from one another, the variation within populations being small; with respect to other markers, the differences are smaller and not equivalent. The existence of the so-called eastern and western clades of this species earlier assumed by other researchers on the basis of mtDNA and morphological data has been confirmed. There are no distinct gradations exceeding individual variation in 14 populations of L. agilis exigua (the eastern clade) with respect to IMP markers, although these populations inhabit a vast area from the Ural Mountains to the Kabardino-Balkar Republic (the Caucasus). These data suggest that the subspecies has been rapidly spreading northwards since the Pleistocene glaciation (about 15,000 years ago).     

Does loss of heterozygosity in critical genome regions predict a local relapse in patients after laryngectomy?

BACKGROUND: Patients, who had an upper aerodigestive tract malignancy, have a high incidence of succeeding tumor development. This has been attributed to the role of "field cancerization" in carcinogenesis. The aim of this study was analysis of loss of heterozygosity (LOH) in the regions frequently lost during the course of head and neck squamous cell carcinomas (HNSCC), especially at early stages, which could answer the clinicians' question, if LOH analysis has any "predictive" value in relation to tumor occurrence. MATERIAL AND METHODS: Sixty-five larynx cancer patients were examined for loss of heterozygosity on 3p, 7q, 8p, 9p and 18q chromosomal arms with the use of 12 microsatellite markers. The material from a single patient consisted of blood, tumor, safe margin and one or two clinically unchanged mucosal samples. During follow up, the material from brush specimens (14 patients) as well as laryngeal swabs (4 patients) was also examined. RESULTS: The highest frequency of LOH was detected for marker D3S1234 in tumor tissues (29%). Analysis of margin samples (b) revealed low LOH frequencies (2-5%) and complete retention of heterozygosity for markers: D3S1234, D7S486, D8S261, D8S264, D9S171 and D18S46. Similarly, for normal appearing mucosa from upper part of larynx (c) frequencies of LOH were low (2-6%), with the complete retention of heterozygosity for markers: D3S1284, D3S1304, D3S1234, D8S264 and D9S1870. We did not detect any LOH in the material of normal appearing mucosa from tracheostoma region (d). During follow up, LOH was detected for eight markers, with the highest incidence for markers D18S46 (six cases), D7S486 (four cases) and D3S1300 (three cases). CONCLUSIONS: The data, obtained during this investigation, did not reveal the predictive value of LOH with respect to local relapse occurrence in laryngeal cancer patients. However, time of follow up did not reach 5 years, so that further clinical monitoring should be conducted.