The cytogeographical distribution pattern ofAllium (Alliaceae) in the Greek Peninsula and Islands

Greece is considered as a secondary centre of evolution for the genusAllium since it possesses about 50% of the species known from the whole Flora Europaea area. In the present investigation 44 GreekAllium spp. have been studied and new chromosome counts are reported from 40 populations and 17 species. The distribution of the different cytotypes (x = 7, x = 8, x = 11 and 2n = 2x, 3x, 4x, 5x, 6x, 7x) in Greece is discussed. From the four phytogeographical subdivisions recognized, South continental Greece shows the greatest species and karyotype diversity. This phenomenon is probably due to the geographical position and to the geological history of this area which has received species and populations from different directions. Subsequently, hybridization apparently has been of evolutionary importance.The genusAllium in Greece I.     

Effects of selection criteria on yield stability in chickpea (Cicer arietinum L.)

Summary Selection in the F₃ generation for seed yield, fruiting branches/plant, effective pods/plant, and seed index (100-seed weight) was carried out in two chickpea crosses. Sixty F₅ lines (15 lines/selection criterion) along with check variety were evaluated for seed yield in three distinct environments. The effects of selection criteria on yield stability was examined using linear regression approach and genotype-grouping technique. There were no differences between selection criteria for linear yield responses of F₅ lines to different environments. Within all four selection criteria the lines showed similar linear responses. The non-linear component was relatively higher for lines selected for effective pods and seed index than lines selected for yield and fruiting branches. On the basis of mean yield and coefficient of variation across environments, the seed index was the least effective selection criterion for developing high yielding and stable lines. When the results of stability parameters and genotype-grouping technique were considered together, selection for yield and fruiting branches was highly effective for isolating stable and high yielding lines.     

Linear and non-linear regression analysis of genotype X environment interactions in pearl millet

Summary Regression analysis was computed on the grain yield of 15 single cross F₁ hybrids of pearl millet (Pennisetum typhoides (Burm.) S. & H.) evaluated in 20 environments at 19 sites in India to assess the nature of genotype X environment interactions. Linear, quadratic, cubic, twoand three-intersecting straight line models were examined for fit. The interactions of six hybrids viz. MH 110, MH 113, MH 114, MH 115, MH 120 and MBH 110 were explained by the linear regression model. The response of the remaining nine hybrids was largely non-linear. The two and three-intersecting straight line models fit better than the quadratic and cubic models and explained non-linearity of response. The two-intersecting straight line models fit for 6 hybrids MH 106, MH 107, MH 112, MH 116, MH 117 and BJ 104. The response of MH 109 was best explained by a three-intersecting straight line model, but there still existed a significant remainder variation. The truncation of environmental range by assuming moving division points was more efficient than the fixed division points for the segmental regression models. The stability of hybrid varieties on the best fitting model has been discussed.     

Decreased fertility in related females heterozygous for the 1/29 chromosome translocation

Eighteen heifers and 120 cows which were descendants of a presumed 1/29 carrier Simmental bull were karotyped. Nine heifers (50%) and 48 cows (40%) were found to be heterozygous for the 1/29 translocation (59, XX, t(1q;29q)). The other animals were chromosomally normal (i.e., 60, XX) or not karotyped. The 48 1/29 cows were compared with 72 chromosomally normal cows with regards to days to first conception, calving interval, percentage of calves conceived, percentage of calves weaned and production efficiency (% calved conceived × % calved weaned). Nine carrier heifers were compared to the nine noncarrier heifers as to pregnancy status. Carrier, noncarrier and nonkarotyped relatives were compared to each other and to contemporary females with regard to pregnancy status at their initial exposure to males. The percentage of calves conceived (calving efficiency) in the 72 noncarrier and the 48 females heterozygous for the 1/29 translocation were 81.5 and 74.8%, respectively (P<0.07). Although days to first conception was longer and percentage of calves weaned and production efficiency were lower in the female heterozygous for the 1/29 translocation, the differences were not statistically different (P>0.10) from the noncarriers. Pregnancy rate was 44.4 and 66.7% (P>0.10) for nine carrier and nine noncarrier heifers, respectively. The pregnancy rate of carrier (65.4%), noncarrier (73.2%) and nonkarotyped (77.8%) relatives of this sire at their mating as yearlings, did not differ (P>0.10). The pregnancy rate as yearlings of carrier females (65.4%) and contemporary heifers (79.8%) did differ (P<0.05). Comparing the pregnancy rate as yearlings of all descendants (72.0%) of the Simmental sire to contemporary heifers (79.8%), a significant decrease (P<0.05) was found indicating that fertility of this sire may have been lower than other sires or that other factors beside the translocation affected fertility.     

Protection of photosynthetic O2 evolution against heat inactivation: the role of chloride,pH and coupling status

Heat inactivation of photosynthetic O₂ evolution was studied in isolated thylakoids from spinach (Spinacia oleracea) and mangrove (Avicennia marina) leaves. Different temperatures, salt, pH and uncoupler effects were investigated. From these results and others in the literature it was concluced that chloride loss from the membrane and, more specifically, the oxygen-evolving complex of photosystem II, may be the cause of inhibition of oxygen evolution during heat inactivation.Abbreviations Hepes 4-(2-hydroxyethyl)-1-piperazinethanesulfonic acid - Tris 2-amino-2-(hydroxymethyl)-1,3-propanediol - Tricine N-2-hydroxy-1, 1-bis (hydroxymethyl) ethyl glycine - EDTA ethylenediaminetetraacetic acid - FeCN K-ferricyanide     

Differences in the Biophysical Properties of the Benzodiazepine/γ-Aminobutyric Acid Receptor Chloride Channel Complex in the Long-Sleep and Short-Sleep Mouse Lines

Significant differences in the thermal stability of benzodiazepine receptors were found in cerebral cortical membranes prepared from the long-sleep (LS) and short-sleep (SS) selected mouse lines. Thus, benzodiazepine receptors from LS mice were heat inactivated (55 degrees C) at a significantly faster rate than those from SS mice. Although gamma-aminobutyric acid (GABA) reduced the rate of heat inactivation in both lines, the more rapid rate of inactivation in the LS line was maintained. Furthermore, the potency of GABA to enhance [3H]flunitrazepam binding decreased threefold in membranes from LS mice as the incubation temperature was increased from 0 degrees to 37 degrees C, but was unaltered in membranes from SS mice. These differences in the biophysical properties of the benzodiazepine/GABA receptor chloride channel complex ("supramolecular complex"), together with a higher KD for t-[35S]butylbicyclophosphorothionate in membranes from LS compared to SS mice, suggest that the supramolecular complex may modulate the differential sensitivity to some depressants and convulsants in these lines.     

Constitutive appearance of peroxisomes in a regulatory mutant of the methylotrophic yeast Hansenula polymorpha

Summary A selection by glucosamine for mutants of Hansenula polymorpha insensitive to glucose repression of methanol assimilation is described. Constitutive synthesis of enzymes is established in standard batch cultures of glucosegrown cells. Upon prolonged glucose metabolism the phenotype is masked by catabolite inactivation and degradation of enzymes. Addition of the substrate methanol remarkably improves constitutive synthesis by preventing catabolite inactivation and delaying degradation. Regular peroxisomes of reduced number are formed in mutant cells under repressed conditions. No constitutive synthesis is detectable using ethanol as a carbon source. In addition, this alcohol is detrimental to growth of the mutants, indicating that H. polymorpha is constrained to repress synthesis of enzymes involved in the C₁-metabolism when ethanol is present as a substrate.     

Synthesis and evaluation of Triticum durum — T. monococcum amphiploids

Summary Nine Triticum durum — T. monococcum amphiploids (AABBA^mA^m) were synthesized by chromosome doubling of sterile triploid F₁ hybrids involving nine T. durum (AABB) cultivars and a T. monococcum (A^mA^m) line. The triploid F₁ hybrids had a range of 4–7 bivalents and 7–13 univalents per PMC. The synthetic amphiploids, however, showed a high degree of preferential pairing of chromosomes of the A genomes of diploid and tetraploid wheats. The amphiploids were meiotically stable and fully fertile. Superiority of four amphiploids for tiller number per plant, 100-grain weight, protein content and resistance to Karnal bunt demonstrated that these could either be commercially exploited as such after overcoming certain inherent defects or used to introgress desirable genes into durum and bread wheat cultivars. Methods for improvement of these amphiploids are discussed.     

五种恙螨染色体核型的研究

恙螨染色体的研究迄今仅Shirai等(1984)简要地报道了三种纤恙螨的染色体核型。本实验采用压片法和改良空气干燥法,研究观察五种恙螨有丝分裂染色体核型。初静止化蛹1—3天的成蛹阶段是制作恙螨有丝分裂染色体标本的最佳虫期。微红纤恙螨,地里纤恙螨和巨螫齿恙螨染色体数目为2n=14;苍白纤恙螨和小板纤恙螨为2n=16。染色体呈大小不等的小棒状,单着丝粒,但多不清晰,仅可见着丝点区浅染。部分核型出现染色体异型现象。核型性别未明,性别决定机制不清。     

The cytogenetic and hepatotoxic effects of dioxin on mouse liver cells

The cytogenetic and hepatotoxic effects of 2,3,7,8-tetrachlorodibenzo p-dioxin (TCDD) on mouse liver cells were investigated. Male C57BL/6J strain mice, which have TCDD receptors, were given single intraperitoneal injections of 25, 37.5, 75 and 150 g of TCDD/kg body weight or corn oil carrier alone. Two-thirds hepatectomies were carried out at 1 or 7 days after injection and chromosomal aberrations and mitotic indexes of the regenerating hepatocytes were scored 54 hr after hepatectomy. Liver sections from additional intact mice were studied for TCDD-hepatotoxicity at 1, 7 and 30 days after injection. The three high doses of TCDD caused hepatotoxicity with necrosis of liver cells and focal architectural collapse by 30 days after injection. No evidence was obtained of an increase in the frequency of chromosomal structural aberrations at doses that allowed sufficient mitotic activity for cytogenetic evaluation. We conclude that TCDD is not a clastogen for mouse hepatocytes, although high doses cause marked hepatocellular necrosis.Abbreviations CSD chromosome deletion - META metacentric chromosome - TCDD 2,3,7,8-tetrachlorobenzo-p-dioxin