Aspartate aminotransferases ofPanicum miliaceum L. andPanicum antidotale retz.

L-Aspartate: 2-oxoglutarate transaminase was isolated and partially purified from leaves ofPanicum miliaceum (C₄, NAD-malic enzyme type) and ofPanicum antidotale (C₄, NADP-malic enzyme type). In each preparation two isoenzymes with different kinetic properties could be characterized. The enzyme activity was irreversibly inhibited by 2-aminooxyacetic acid and by 2-amino-4-methoxy-3-butenoic acid. The first inhibitor reacted with pyridoxal 5-phosphate, and its inhibition could be reversed by the exchange of the modified coenzyme. The second inhibitor binds not only to the coenzyme pyridoxal 5-phosphate, but also to the apoprotein. The results of the dissociation and reconstitution experiments were in agreement with the kinetic data, showing that the mode of inactivation was different for 2-aminooxyacetic acid and 2-amino-4-methoxy-3-butenoic acid.     

Genetic relationships among the annual species of Cicer L.

Summary Genetic relationships between 7 annual species of the genus Cicer, including the cultivated chickpea, have been studied. These species were assigned to 3 crossability groups. In each group interspecific hybrids could be obtained but their fertility differed considerably in the various cross combinations. Crosses between members of different groups yielded no viable seeds. The possibility of gene transfer from the wild species to the cultivated chickpea C. arietinum was also assessed. Only two species could be considered for this purpose, C. reticulatum, which is the wild progenitor of the cultivated species, and C. echinospermum, which is in the secondary gene pool of C. arietinum. A unique postzygotic reproductive barrier mechanism was found between the members of Group II, C. judaicum, C. pinnatifidum and C. bijugum. It is based on a disharmony in the growth rate of the stigma and the anthers at the time of anthesis of the F₁ interspecific hybrid so that selfpollination is avoided. It is proposed that this kind of mechanism has been involved only when an effective spatial isolation between the three species had been obtained.     

Molecular classification and phylogenetic relationships of selected edible Basidiomycetes species

Morphological identification of edible mushrooms can sometimes prove troublesome, because phenotypic variation in fungi can be affected by substrate and environmental factors. One of the most important problems for mushroom breeders is the lack of a systematic consensus tool to distinguish different species, which are sometimes morphologically identical. Basidiomycetes as one of the largest groups of edible mushrooms have become more important in recent times for their medicinal and nutritional properties. Partial rDNA sequences, including the Internal Transcribed Spacer I-5.8SrDNA-Internal Transcribed Spacer II, were used in this study for molecular identification and assessment of phylogenetic relationships between selected edible species of the Basidiomycetes. Phylogenetic trees showed five distinct clades; each clade belonging to a separate family group. The first clade included all the species belonging to the Pleurotaceae (Pleurotus spp.) family; similarly, the second, third, fourth, and fifth clades consist of species from the Agaricaceae (Agaricus sp.), Lyophllaceae (Hypsigygus sp.), Marasmiaceae (Lentinula edodes sp.) and Physalacriaceae (Flammulina velutipes sp.) families, respectively. Moreover, different species of each family were clearly placed in a distinct sub-cluster and a total of 13 species were taken for analysis. Species differentiation was re-confirmed by AMOVA analysis (among the populations: 99.67%; within: 0.33%), nucleotide divergence, haplotyping and P value. Polymorphism occurred throughout the ITS regions due to insertion-deletion and point mutations, and can be clearly differentiated within the families as well as genera. Moreover, this study proves that the sequence of the ITS region is a superior molecular DNA barcode for taxonomic identification of Basidiomycetes.     

Competitive relationships between two water plant species: Najas marina L. and Myriophyllum spicatum L.

The interrelationships between two submerged macrophytes, Najas marina and Myriophyllum spicatum, were investigated. Double-reciprocal analysis was used to distinguish between the possible types of negative relationships. Results have demonstrated that interspecific inhibition was more severe than the intraspecific one. The intensity of inhibition was negatively correlated with the density of the examined species. The mutual inhibitory effect and the pattern of the obtained results suggest that competitive relationships exist between Najas marina and Myriophyllum spicatum.     

Cytological relationships in theConvolvulus pluricaulis complex

InConvolvulus pluricaulis Chois. two forms (2n=18, 36) along with one colchicine-autotetraploid have been investigated morphologically and cytologically. The diploid regularly formed 9_II although in the “off-season” plants certain irregularities were observed including formation of unreduced pollen grains. The natural tetraploid and the colchicine-autotetraploid had mean frequencies of configurations of 1.56_IV+14.04_II+1.48_I and 2.95_IV+0.56_III+11,43_II+0.8_I, respectively. The mode of chromosome association in the two types of tetraploids was comparable. A comparison of the morphological characters of the two tetraploid types, further, suggested close similarity. In addition they were indistinguishable from the diploid from except being gigas. From these data it is inferred that the natural tetraploid presumably arose as a result of direct duplication of the diploid form, through the chance fusion of unreduced spores. The lower quadrivalent frequency of the natural polyploid is ascribed to a gradual shift towards bivalent association accompanying natural selection for fertility. The taxonomic status of the two forms (2x, 4x) is discussed and the varietal status accorded to the tetraploid form is supported.     

Cytological studies on triploid Trigonella corniculata L.

Two spontaneous triploid plants of Trigonella corniculata (3n=24) were observed in a population raised from irradiated seeds. Up to seven trivalents per cell were observed. One of the plants appeared to be a double translocation heterozygote involving two non-homologous chromosomes, and therefore could form a quadrivalent, a ring trivalent and bivalents without corresponding univalents.     

Weight–length relationships for selected fish species of the western Mediterranean Sea

Weight–length relationships are presented for 24 species of the western Mediterranean Sea (Spain). These species were selected from samplings made during November 1995. The captures were made by beam trawl in Posidonia oceanica meadows up to depths of 20–22 m.     

Response ofPanicum maximum Jacq. to inoculation withAzospirillum brasilense

Summary The effects on plant dry weight and acetylene reduction activity after applyingAzospirillum brasilense (strain 13t) to guineagrass,Panicum maximum Jacq., grown in clay pots under greenhouse conditions, are reported and discussed.     

Ultra-sculpturing of seed morphotypes in selected species of genus Salvia L. and their taxonomic significance

• The taxonomic importance of macromorphological and micromorphological seed characteristics was investigated using SEM of ten species of the Salvia genus from Pakistan. The aim was to identify diagnostic seed ultrastructural features that could aid in species delimitation, correct identification and phylogenetic position. The ultrastructure of Salvia varies greatly, and a wide range of unique micromorphological features have been observed.
• Seed micromorphological features were explored by SEM, including seed shape, colour, texture, cell outline, surface sculpturing, epidermal cell arrangement, anticlinal, and periclinal wall pattern.
• Seed shapes were categorized as obovate, spherical, spheroid, broadly elliptic, elliptic and oblong, mostly with a terminal hilum. Seed colours were black, light brown, dark brown, brown and yellow. Exo-morphological characters, i.e. epidermal cell arrangements, included irregular, wavy pentagonal-hexagonal, regular pentagonal-hexagonal. Cluster analysis was used to assess similar and distinct species within Salvia with a feasible explanation. Taxonomic keys were made based on micromorphological qualitative features that help to delimit species and identify them quickly within the Salvia genus.
• Seed morphology of ten Salvia species was described and investigated, and the diagnostic significance of features evaluated using SEM. This study analysed seed features, especially at the species level, which might provide much new taxonomic information. The results revealed that, in seed morphology, using SEM can help with taxon identification, especially at the genus and species levels.

     

Genetic relationships among South American species of Cunila D. Royen ex L. based on ISSR

Cunila species are among the commonly used South Brazilian plants in popular medicine. This genus presents two centers of distribution in North and South America; the latter being classified into three sections: Incanae, Incisae and Spicatae. Based on the prospective utility as aromatic and medicinal plants, the aim of this work was to examine the genetic diversity among the South American species to contribute to the knowledge of their botanical sections. In this context, 11 Cunila species were analyzed by ISSR using seven primers that generated a total of 107 bands. The relationship was evaluated by constructing dendrograms using the UPGMA algorithm and analysis of principal components. The cluster analysis places the species C. origanoides with the South American species, but forming an independent cluster. Remarkably, among South American species two clusters emerge, one consisting of shrubs and the second by subshrubs species, which refines the botanical taxonomy for several species of the genus.     

羽叶薰衣草雄性不育的细胞学研究

用光镜和电镜观察羽叶薰衣草(Lavandula pinnata L.)雄性不育小孢子发育过程的细胞形态学特征.结果表明:羽叶薰衣草花药4枚,每枚花药通常具4个小孢子囊.花药壁发育为双子叶型,从外向内分为表皮、药室内壁、中层和绒毡层4层细胞.减数分裂形成的四分体为四面体及十字交叉型.小孢子的发育过程可分为造孢细胞期、减数分裂时期、小孢子发育早期、小孢子发育晚期.未观察到二胞花粉期和成熟花粉期.羽叶薰衣草花粉败育主要发生在单核花粉时期,细胞内物质解体并逐渐消失变成空壳花粉或花粉皱缩变形成为各种畸形的败育花粉.在此之前小孢子的发育正常.羽叶薰衣草小孢子不育机制体现在绒毡层过早解体、四分体时期以后各细胞中线粒体结构不正常、胼胝质壁与小孢子母细胞脱离、花药壁细胞中淀粉出现时间异常等. 壁发育为双子叶型,从外向内分为表皮、药室内壁、中层和绒毡层4层细胞.减数分裂形成的四分体为四面体及十字交叉型.小孢子的发育过程可分为造孢细胞期、减数分裂时期、小孢子发育早期、小孢子发育晚期.未观察到二胞花粉期和成熟花粉期.羽叶薰衣草花粉败育主要发生在单核花粉时期,细胞内物质解体并逐渐消失变成空壳花粉或花粉皱缩变形成为各种畸形的败育花粉.在此 前小孢子的发育正常.羽叶薰衣草小孢子不育机制体现在绒毡层过早解体、四分体时期以后各细胞中线粒体结构不正常、胼胝质壁与小孢子母细胞脱离、花药壁细胞中淀粉出现时间异常等. 壁发育为双子叶型,从外向内分为表皮、药室内壁、中层和绒毡层4层细胞.减数分裂形成的四分体为四     

Nucleic acid homologies of selected bacteria, L forms, Mycoplasma species

Rogul, M. (Walter Reed Army Institute of Research, Washington, D.C.), Z. A. McGee, R. G. Wittler, and Stanley Falkow. Nucleic acid homologies of selected bacteria, L forms, and Mycoplasma species. J. Bacteriol. 90:1200-1204. 1965.-The molar per cent of guanine plus cytosine (G + C) in the deoxyribonucleic acids (DNA) of Proteus mirabilis, strain 9, and its stable L form was determined by thermal denaturation and found to be approximately 39.5% G + C. The DNA homologies of this bacterium and its L form were estimated by the agar-column technique and were equivalent in their abilities to anneal and form specific duplexes. The next series of comparisons were performed between two Mycoplasma species and their often suggested bacterial parent. The G + C ratios of M. gallisepticum (32.7%), M. gallinarum (28.1%), and Haemophilus gallinarum (41.9%) varied to a high degree. In the homologous system, the denatured DNA of H. gallinarum trapped in agar bound approximately 40% of its sheared, denatured, and H(3)-labeled DNA. In comparison, the nucleic acids of M. gallinarum and M. gallisepticum were incapable of binding the labeled DNA of H. gallinarum. These findings provided evidence that the two strains of Mycoplasma were not derived from H. gallinarum.     

Cytological studies in some species of Momordica

In the genus Momordica three species M. charantia, M. balsamina and M. dioica, have been cytologically investigated. M. dioica has a more asymmetrical karyotype than the other two species.Meiosis in the three species is regular. The strictly monoecious M. charantia and M. balsamina show similarity in the range and frequency of bivalents and chiasmata, whereas M. dioica, a dioecious species, has fewer half chiasmata per chromosome. The evolutionary significance of perennial and annual habits along with allogamous and autogamous breeding systems is discussed. The incompatibility between 2n=22 and 2n=28 species in this genus is strongly indicated by the negative results of crossings between M. charantia and M. balsamina on one side and M. dioica on the other. The possible origin of M. dioica from M. charantia is discussed.This research has been financed in part by a grant made by the United States Department of Agriculture under PL 480.     

Study of pollen brush in selected species of Astragalus L. subgenus Pogonophace Bunge (Leguminosae)

Nine species of Lippia (Verbenaceae) were studied by RAPD markers in order to evaluate the degree of genetic diversity. The following species were collected at the Cadeia do Espinhaço Mountains, Southeast Brazil: L. corymbosa, L. diamantinensis, L. filifolia, L. florida, L. hermannioides, L. lupulina, L. rotundifolia, L. rosella and L. sidoides. The analysis was performed using 18 primers that generated 490 fragments and only one primer was found to be monomorphic in all individuals. The average interspecific genetic distances were similar for all species and higher than the intraspecific genetic distances. Species with narrow occurrence did not show low intraspecific diversity. The molecular data were used to generate an UPGMA dendrogram that showed two major groups with a clear distribution among the species. RAPD analysis was efficient to address the genetic diversity of Lippia species and contributed to understand the adaptation to the environment, conservation and taxonomic implications.     

食用稗成熟胚的组织培养及其细胞学特性

研究食用稗成熟胚培养因素的结果表明,愈伤诱导最适培养基为N6＋3．0mg·L^-12,4-D。N6基本培养基上的愈伤组织分化率较高;B5＋3．0mg·L^-12,4-D＋1．0mg·L^-16-BA的愈伤组织也具有较高的分化率。分化培养基N6＋2．0mg·L^-16-BA＋0．5mg·L^-1NAA利于绿芽分化;。茎尖部位的愈伤组织分化率比根的高。最佳生根培养基为1／2MS＋0．2mg·L^-1～NAA＋1．0g·L^-1AC。解剖和塑料半薄切片技术观察食用稗外植体的形态学和细胞学变化显示,胚根和胚轴主要形成非胚性愈伤组织,茎尖部位形成胚性愈伤组织。食用稗的器官建成途径倾向于以不定芽途径再生植株。芽原基为外起源,而根原基为内外起源兼有。     

Serological relationships among some Pichia species.

Antigenic analyses of five species of the genus Pichia were carried out for taxonomic study by the slide agglutination method using monospecific and absorbed antisera and the agglutinin absorption technique. Comparative studies were also performed with a few strains of each of the same species and their classifications are discussed with respect to the antigenic structures and the patterns of proton magnetic resonance (PMR) spectra of their cell wall polysaccharides. ichia delftensis and Pichia zaruensis possessed thermostable antigens 1,2,5 and 11, and the former had also thermoabile antigen m. Both species were closely related to Candida krusei. Pichia toletana possessed thermostable antigens 1,2,5,11,17 and 49. Pichia bovis contained thermostable antigens 1,2,14,15,16,20 and 21, and it was related to most species of the genus Hansenula, although assimilation of potassium nitrate was negative. Finally, Pichia etchellsii possessed thermostable antigens 1,2,3,4,9 and 14, and was closely related to Pichia vini. Patterns of PMR spectra of mannans of these species also supported their serological relationships. Therfore, P. delftensis, P. zaruensis and P. etchellsii are considered to be the synonyms of Pichia fluxuum, Pichia dispora and P. vini respectively, although P. toletanan and P. bovis are independent species.     

Nucleic acid relationships among Acholeplasma species.

3H-labeled Acholeplasma DNA probes were generated in vitro by the nick-translation method and used to determine the nucleotide sequence homology among the type strains of the eight currently recognized species of Acholeplasma. Very little nucleotide sequence homology (less than or equal to 18%) was found among the eight species, with heteroduplexes showing at least 12% or more mismatching as determined by thermal elution midpoints. The small amount of nucleotide sequence homology among the eight species indicates that these species are quite distinct and are not closely related to each other genomically.     

Isozyme variation and species relationships in the genus Lolium L. (ryegrasses,Graminaceae)

Thirty-two natural populations belonging to the eight species of the genus Lolium (ryegrass) or to Festuca pratensis (meadow fescue) were recorded for allelic frequencies at 13 isozyme loci. Cultivated ryegrass (L. perenne and L. multiflorum), meadow fescue, and the annual L. rigidum, are true outbreeders. The other species are true inbreeders, except for L. canariense, which shows a moderate level of cross fertilisation (20%). Hierarchical clustering from Nei's unbiased distance leads to four groups. The three self-pollinating, weed species, L. temulentum, L. remotum and L. persicum, belong to the first cluster, which is the most differentiated one. The second cluster comprises L. multiflorum, L. subulatum and most populations of L. rigidum. All L. perenne populations belong to the third cluster, as do two of L. rigidum. The average genetic distance within the L. perenne group is very low. Surprisingly, the fourth cluster groups together L. canariense and Festuca pratensis. The data suggest that L. rigidum is the species with the greatest diversity, and could be a common ancestor of the genus. Knowledge of historical processes of domestication could help to calibrate the molecular clock.