Chromosome number,morphology, pairing,and DNA values of species and hybrids in the genusFallopia (Polygonaceae)

The taxa in this study have in the past been treated together in sect.Tiniaria Meissner ofPolygonum L. s.l., and more recently the large erect rhizomatous herbaceous perennials have been separated from the twining annuals and perennials as the generaReynoutria andFallopia respectively. These taxa range in ploidy level from diploid to octoploid, with base numbers of both 10 and 11 present. The plants are primarily Asiatic in distribution, although many of the large erect perennials are now naturalized in many parts of Europe. Cytological examination has revealed the presence of a number of previously unknown hybrid taxa in the British Isles. The readiness with which hybridisation occurs between taxa of differing base number and ploidy level, and similarities revealed in chromosome morphology, meiotic pairing and in DNA C-value, suggest to the authors that these two genera are best amalgamated underFallopia.     

The antennae of neopseustid moths: Morphology and phylogenetic implications, with special reference to the sensilla (Insecta, Lepidoptera, Neopseustidae)

The antennae of Lepidoptera Neopseustidae were examined with the scanning electron microscope. The studied species, Nematocentropus cfr. omeiensis, Neopseustis meyricki, Synempora andesae, Apoplania valdiviana and Apoplania penai possess nine types of antennal flagellum sensilla: multiporous large sensilla basiconica, multiporous thin sensilla basiconica, multiporous small sensilla basiconica, multiporous sensilla trichodea, multiporous sensilla coeloconica; uniporous sensilla chaetica; aporous sensilla chaetica, aporous stylus-shaped sensilla chaetica, aporous sensilla styloconica.The multiporous sensillum type here termed “multiporous large sensillum basiconicum” is unknown from other Lepidoptera and probably constitutes an autapomorphy of the family Neopseustidae. This sensillum type is remarkable by having a single base in female Apoplania and Synempora while in male Apoplania it has a bifid or trifid base, and in male Synempora it is composed of two or three incompletely separated hairs. This may be the first recorded example of a sexually dimorphic lepidopteran sensillum type. The stylus-shaped sensillum chaeticum is a primitive type which occurs only in some lower Lepidoptera.     

A further note on the relationships of the EuropeanLinum hologynum and the Australian species ofLinum (Linaceae)

The diploid chromosome number for the EuropeanLinum hologynum and the haploid number for the AustralianL. monogynum is 42 and appears to establish a new and distinctive base number for sect.Linum. The possession by these two species and by the AustralianL. marginale of multiporate pollen and united styles, a unique combination of features in sect.Linum, may warrant the establishment of a new subsection in that section to accommodate the three species.     

A new species of <Emphasis Type="Italic">Lonchocarpus</Emphasis> (Leguminosae,Papilionoideae) from Mato Grosso do Sul,Brazil

Lonchocarpus variabilis, from Mato Grosso do Sul State in Midwestern Brazil, is newly described and illustrated on the basis of field and herbarium studies. It occurs in seasonally deciduous forests and gallery forests at 150–681 m elevation. This species grows in sandy, calcareous, and iron rocky soils. It is similar to L. fendleri, but differs in number of leaflets and shape of the calyx. Moreover, L. variabilis has a staminal tube dilated at the base and anthers with a glabrous base.     

Arrangement and size distribution of repeat and single copy DNA sequences in four species ofCucurbitaceae

DNA sequence organization patterns have been studied in fourCucurbitaceae plant species, namely,Luffa cylindrica (sponge gourd),L. acutangula (ridge gourd),Benincasa hispida (ash gourd) andCoccinia indica (ivy gourd). Extensive interspersion of repeat and single copy sequences has been observed in sponge gourd and ridge gourd. In ash gourd and ivy gourd, however, there is a limited interspersion of these sequences and a large portion of the single copy DNA remains uninterspersed. The interspersed repetitive sequences are composed of a major class (75–80%) of short repeats (300 base pairs long) and a minor class (15–20%) of long repeats (2 000–4 000 base pairs) in all the four species. The average length of single copy sequences dispersed among repeats is 1 800–2 900 base pairs. In spite of these gross similarities in the genome organization in the four species, the fraction of repeats and single copy sequences involved in short and long period interspersion patterns, and fraction of single copy sequences remaining uninterrupted by repeats are vastly different. The probable implications of these differences with respect to speciation events and rates of genome evolution are discussed.Molecular Analysis ofCucurbitaceae Genomes, III. — NCL Communication No.: 3595.     

商陆属2种植物花器官发生过程观察

该研究采用扫描电镜观察红蕊商陆(Phytolacca esculenta)和浙江商陆(Phytolacca zhejiangensis)的花器官发生过程,以明确商陆属植物花的基数,以及雄蕊和雌蕊是否具有叶性器官发生的特点,阐明商陆属植物花发生的模式。观察结果显示:(1)红蕊商陆和浙江商陆在花原基发生后,小苞片以2/5圆周相继发生,花被片的发生紧接小苞片的发生进行,花被与小苞片的发生均有顺时针和逆时针方向,且二者的发生方向始终一致。(2)花被发生结束后,雄蕊在花顶端分生组织的环状分生组织上发生,没有明显的发生顺序,近似同时发生;2轮雄蕊时内轮雄蕊先发生;外轮雄蕊有少数有时偶然与花被互生,但因外轮雄蕊数多于花被数,雄蕊与花被常不互生,也没有规律性。(3)红蕊商陆和浙江商陆的心皮都在雄蕊发生后,紧接着开始发生,且雌蕊与雄蕊(或内轮雄蕊)互生发生;心皮没有发生的先后次序,且每个心皮在基部连成一个整体形成雌蕊基部并发育成为子房。(4)红蕊商陆和浙江商陆的花基数为5,雄蕊和雌蕊的发生及数目不符合5基数的特点。研究认为,红蕊商陆和浙江商陆为5基数花,该研究结果不支持商陆属植物为3基数花的发生模式。     

Chromosome counts inCalea (Asteraceae-Heliantheae)

Chromosome numbers are reported for six taxa ofCalea, among them tetraploidC. septuplinervia, the only known polyploid inCalea s. str. The base chromosome number ofCalea is interpreted as x = 19.     

Nectary structure and nectar characteristics in someBignoniaceae

The nectary structure and chemical nectar composition of 15 species belonging to 12 genera ofBignoniaceae are analyzed. All taxa bear a conspicuous nuptial nectary surrounding the ovary base. The secretory tissue is mostly supplied by phloem branches. The stomata are located in the middle and upper part of the nectary epidermis with an homogeneous distribution. The nuptial nectary is proportionally large in relation to the ovary (15–30%), disregarding the nectary volume. Most species have extranuptial nectaries in both inner and outer surfaces of the calyx. Both kinds of nectaries lack a vascular tissue that straightly supplies them. Nuptial nectar concentration (wt/wt) ranges from 19 to 68%. Sugars and amino acids are found in all species. Half of the species have hexose predominant nectars, the remaining sucrose predominant. Phenols are detected in only three species, whereas reducing acids exclusively inTecoma stans. Alkaloids and lipids were never detected. Extranuptial nectar chemical composition is analyzed in two species:Dolichandra cynanchoides andPodranea ricasoliana. Bees constitute the main flower visitors of the species studied whereas hummingbirds were seen visiting three species. A correlation analysis is performed with the data obtained. There are a few significant correlations which indicate a parallel increase of three parameters: the longer the flower length, the more voluminous the nectary and the higher stomata number, independently of the floral biotype. Phenograms are obtained using 24 floral characters including nectary and nectar data. The clusters obtained do not reflect taxonomic relationships but are useful in the understanding of animal-plant interactions when the flower biotype is considered.This paper is based on a chapter of a doctoral thesis presented at the University of Córdoba (Argentina).     

Phylogenetic relationships in gnetophyta deduced fromrbcL gene sequences

Part of the large subunit of the ribulose-1,5-bisphosphate carboxylase gene (rbcL) was sequenced (1333 base pairs) from three species of gymnosperms:Ephedra sinica Gnetum parvifolium, Welwitschia mirabilis. Phylogenetic trees inferred from the neighbor joining, Wagner parsimony and maximum likelihood methods showed thatGnetum andWelwitschia were more closely related to each other than either is toEphedra within Gnetophyta, and the result supports previous cladistical analysis of morphological data.     

Identification and molecular characterization of a large insertion within the repetitive domain of a high-molecular-weight glutenin subunit gene from hexaploid wheat

High-molecular-weight (HMW) glutenin subunits are a particular class of wheat endosperm proteins containing a large repetitive domain flanked by two short N- and C-terminal non-repetitive regions. Deletions and insertions within the central repetitive domain has been suggested to be mainly responsible for the length variations observed for this class of proteins. Nucleotide sequence comparison of a number of HMW glutenin genes allowed the identification of small insertions or deletions within the repetitive domain. However, only indirect evidence has been produced which suggests the occurrence of substantial insertions or deletions within this region when a large variation in molecular size is present between different HMW glutenin subunits. This paper represents the first report on the molecular characterization of an unusually large insertion within the repetitive domain of a functional HMW glutenin gene. This gene is located at the Glu-D1 locus of a hexaploid wheat genotype and contains an insertion of 561 base pairs that codes for 187 amino acids corresponding to the repetitive domain of a HMW glutenin subunit encoded at the same locus. The precise location of the insertion has been identified and the molecular processes underlying such mutational events are discussed.     

Examination of the hybrid origin of the wild potato Solanum ruiz-lealii Brücher

The common potato, tetraploid Solanum tuberosum spp. tuberosum L. (tbr), has a narrow genetic base but a large number of related tuber-bearing species that harbor genetic diversity for agronomic characters. The taxonomic status of Solanum ruiz-lealii Brücher (rzl), a diploid species endemic to Mendoza province, Argentina, is controversial. It has been described as a new species of non-hybrid origin and as a natural hybrid between S. kurtzianum Bitt. & Wittm. (ktz) and S. chacoense Bitt. (chc). The hypothesis of the hybrid origin of rzl is examined systematically for the first time by phenetic analyses of morphological and molecular (SSR markers) data, and cytological analyses of interspecific hybrids. The morphological, cytological and molecular data are congruent, and suggest that rzl is not a recent natural hybrid between the ktz and the chc populations studied but has probably originated by divergence of chc, or by hybridization between chc and another taxon.     

Distribution of soil invertase in relation to the root systems ofPicea sitchensis (Bong.) Carr. andAcer pseudoplatanus L. during development of young plants

A method is described for sampling rhizosphere soil under newly establishedPicea sitchensis andAcer pseudoplatanus. The technique involves taking soil samples to a depth of 150 mm at 100 mm intervals along transects, each 45° from its neighbour, radiating from the base of the stem. Invertase activities were measured in the soil samples and compared to their activities in fallow and rhizosphere soils. When the field soil was dry, the tree root systems were carefully excavated to retain as many fine roots as possible. The distribution of the soil invertase was matched to the spatial distribution of the roots showing the precise position of the rhizosphere relative to the initial blind soil sampling. Statistics were applied to derive equations for calculating the percentage enzyme activity relative to that found in rhizosphere soil at various locations radiating from the base of the stem. This information was subsequently applied to soil sampled under trees of the same age as those excavated to give a non-destructive method for sampling rhizosphere soil routinely from under a large number of trees.     

Identification and analysis of the Shewanella oneidensis major oxygen-independent coproporphyrinogen III oxidase gene

Shewanella oneidenesis MR-1 is a facultative anaerobe that can use a large number of electron acceptors including metal oxides. During anaerobic respiration, S. oneidensis MR-1 synthesizes a large number of c cytochromes that give the organism its characteristic orange color. Using a modified mariner transposon, a number of S. oneidensis mutants deficient in anaerobic respiration were generated. One mutant, BG163, exhibited reduced pigmentation and was deficient in c cytochromes normally synthesized under anaerobic condition. The deficiencies in BG163 were due to insertional inactivation of hemN1, which exhibits a high degree of similarity to genes encoding anaerobic coproporphyrinogen III oxidases that are involved in heme biosynthesis. The ability of BG163 to synthesize c cytochromes under anaerobic conditions, and to grow anaerobically with different electron acceptors was restored by the introduction of hemN1 on a plasmid. Complementation of the mutant was also achieved by the addition of hemin to the growth medium. The genome sequence of S. oneidensis contains three putative anaerobic coproporphyrinogen III oxidase genes. The protein encoded by hemN1 appears to be the major enzyme that is involved in anaerobic heme synthesis of S. oneidensis. The other two putative anaerobic coproporphyrinogen III oxidase genes may play a minor role in this process.     

Shared molecular characteristics of successfully transformed mitochondrial genomes in <Emphasis Type="Italic">Chlamydomonas</Emphasis><Emphasis Type="Italic">reinhardtii</Emphasis>

Three types of respiratory deficient mitochondrial strains have been reported in Chlamydomonas reinhardtii: a deficiency due to (i) two base substitutions causing an amino acid change in the apocytochrome b (COB) gene (i.e., strain named dum-15), (ii) one base deletion in the COXI gene (dum-19), or (iii) a large deletion extending from the left terminus of the genome to somewhere in the COB gene (dum-1, -14, and -16). We found that these respiratory deficient strains of C. reinhardtii can be divided into two groups: strains that are constantly transformable and those could not be transformed in our experiments. All transformable mitochondrial strains were limited to the type that has a large deletion in the left arm of the genome. For these mitochondria, transformation was successful not only with purified intact mitochondrial genomes but also with DNA-constructs containing the compensating regions. In comparison, mitochondria of all the non-transformable strains have both of their genome termini intact, leading us to speculate that mitochondria lacking their left genome terminus have unstable genomes and might have a higher potential for recombination. Analysis of mitochondrial gene organization in the resulting respiratory active transformants was performed by DNA sequencing and restriction enzyme digestion. Such analysis showed that homologous recombination occurred at various regions between the mitochondrial genome and the artificial DNA-constructs. Further analysis by Southern hybridization showed that the wild-type genome rapidly replaces the respiratory deficient monomer and dimer mitochondrial genomes, while the E. coli vector region of the artificial DNA-construct likely does not remain in the mitochondria.     

A naturally occurring point mutation in the 13-mer R repeat affects the <Emphasis Type="Italic">oriC</Emphasis> function of the large chromosome of <Emphasis Type="Italic">Vibrio cholerae</Emphasis> O1 classical biotype

The genome of Vibrio cholerae consists of two circular chromosomes of different sizes. Here, a comparative analysis of the replication origins of the large chromosomes (oriCI_VC) of classical and El Tor biotypes of the pathogen is reported. Extensive nucleotide sequence analyses revealed that the oriCI_VC region has six DnaA boxes instead of the five found in Escherichia coli oriC. The additional DnaA box, designated R_V, was unique in V. cholerae as well as in other members of the family Vibrionaceae. However, R_V was not found to be essential for the autonomous replication function of the 307-bp oriCI_VC minimal region. In contrast to El Tor and the recently evolved V. cholerae O139 strains, the oriCI_VC region of the classical biotype showed only a single base transition (TG) in a highly conserved AT-rich 13-mer R repeat region. From the minichromosome copy number and its transformational efficiency analyses, it appears that the single base substitution in the oriCI_VC of the classical biotype has a significant effect on its replication initiation.     

连蕊芥(十字花科)一新异名

连蕊芥属(Synstemon Botsch.)为蒙古高原特有属,根据大量的腊叶标本和野外居群调查,将陆氏连蕊芥(Synstemon lulianlianus Al-Shenhbaz et al.)作为连蕊芥(Synstemon petrovii Botsch.)的异名处理,确认连蕊芥属为单种属。     

Atrosalarias hosokawai, a new species of blenny (perciformes: Blenniidae) from the western pacific

A new species of blenny,Atrosalarias hosokawai is described on the basis of 15 specimens from the western Pacific. It is distinguished from the only known congeneric species,A. fuscus (=A. fuscus fuscus+A. fuscus holomelas), by the following: supraorbital cirrus broad and flat (vs. slender and thread-like inA. fuscus); dorsal fin broadly contacting caudal fin (vs. narrow contact); anal fin narrowly contacting caudal fin (vs. usually free or (rarely) very narrow contact); posteriormost dorsal and anal fin rays long (vs. short); first or posteriormost soft dorsal fin ray shortest (vs. posteriormost ray shortest); first soft anal fin ray shortest (vs. posteriormost ray shortest); caudal fin rays branched in specimens over 36.0 mm SL (vs. unbranched); a large dark spot on base of pectoral fin absent (vs. present or absent); a red margin on anterior dorsal fin absent (vs. present). Futhermore,A. hosokawai differs fromA. f. fuscus in having a lower number of dorsal fin spines (ten vs. eleven) and geographical distribution (western Pacific Ocean vs. Indian Ocean and Red Sea). AlthoughA. hosokawai occurs sympatrically withA. f. holomelas, it can be further distinguished from the latter in lacking a large dark spot on base of pectoral fin.     

Directional selection in lines founded from different parts of the phenotypic distribution of sternopleural chaetae number in Drosophila melanogaster

Summary Divergent directional selection lines were initiated from base populations founded from parents taken from different parts of the sternopleural chaetae distribution in a cage population of Drosophila melanogaster. Lines founded from parents taken from the central part of the distribution showed greater response and higher realised heritability than lines derived from parents with extreme high or extreme low chaetae number. The results suggest that centrally derived phenotypes have higher heterozygosity for chaetae factors than extreme phenotypes and that these factors have a large effect on the character.     

The spectra of base substitutions induced by the impCAB, mucAB and umuDC error-prone DNA repair operons differ following exposure to methyl methanesulfonate

We have used the lacZ reversion assay to study the mutation spectra induced by the Escherichia coli chromosomal umuDC operon and of its two plasmid-borne analogues impCAB and mucAB following exposure of cells to UV light and methyl methane-sulfonate (MMS). We have shown that the impCAB, mucAB and umuDC operons all produce a similar response to UV light which results almost exclusively in AT GC transitions. However, we found that the three operons produced different responses to alkylating agents. We found that with MMS the chromosomal umuDC operon produced almost exclusively AT GC transitions, whilst both mucAB and impCAB produced predominantly transversions. In the case of the impCAB operon the mutation spectrum contained more AT TA than GC TA transversions; this balance was reversed with mucAB. The effect of the copy number of the error-prone DNA repair operons upon the mutagenic spectra was also studied. The results obtained suggest that the copy number of the imp operon does not greatly affect the specificity of base substitutions observed. However, an increase in the copy number of the umuDC operon greatly affected the specificity of base substitution, such that virtually no transitions were produced and the spectrum was dominated by GC/AT TA transversions. It appears that the three error-prone DNA repair operons impCAB, mucAB and umuDC, despite showing strong structural and functional homologies, can display major differences in the spectrum of base changes induced during mutagenesis. We propose that the type of misincorporation/chain extension which DNA polymerase III is allowed to synthesize on a damaged DNA template is extremely sensitive to both the amount and type of error-prone repair proteins present. The modulation of these events by the different proteins can result in widely different mutagenic changes in the repaired DNA.     

The architecture of the flagellar apparatus ofPrymnesium patellifera (Prymnesiophyta)

The flagellar apparatus of the small prymnesiophytePrymnesium patellifera has been analysed and a reconstruction is presented. Externally, the cell carries two sub-equal flagella and a short non-coiling haptonema. Within the cell, there are four microtubular roots and a number of fibrous bands, the latter interconnecting the two basal bodies and the haptonema base. One of the roots (r1) consists of a sheet of up to 25 microtubules originating close to the proximal extremity of the haptonema base, but the other three roots are composed of between 1 and 4 microtubules only. Distally, a large striated fibrous auxiliary connecting root extends across the anterior part of the cell linking root r1 and a mitochondrial profile on the opposite side of the cell. The arrangement of the components of the flagellar apparatus ofP. patellifera is commensurate with the general pattern found in many prymnesiophytes other than members of the Pavlovales, but there are a number of differences in detail from the other species described hitherto.