Seed morphology of Erica L. sect. Loxomeria Salisb. ex Benth., sect. Eremocallis Salisb. ex Benth. and sect. Brachycallis I. Hansen,and its systematic implications

Abstract

Several quantitative and qualitative seed characters of the seven European species of Erica sect. Loxomeria, Eremocallis and Brachycallis were studied. Two main seed types are found based on size and shape: regular ellipsoid or oblong seeds of ca. 0.4 mm for E. ciliaris and the E. tetralix group, and curved to kidney‐shaped seeds of 0.6–0.9 mm for E. cinerea, E. maderensis and E. terminalis. The testa surface in E. ciliaris is reticulate, with indented outer periclinal walls. Erica cinerea has inflated outer anticlinal walls. This character is exclusive for this species within the European (and nearby areas) species of the genus. The seeds of E. maderensis are similar to those of E. terminalis. According to seed morphology, the classical infrageneric classification, by which E. terminalis would be grouped with the E. tetralix group in sect. Eremocallis and E. maderensis in sect. Brachycallis with E. cinerea, is artificial.     

CHROMOSOME NUMBERS IN COMPOSITAE. VI. SENECIONEAE. II

Chromosome counts are reported for 76 taxa and 2 natural hybrids of tribe Senecioneae (Compositae). First counts are reported for several species of Senecioneae as well as for the genera Cadiscus and Whitneya. New chromosome numbers are added to those previously known in Arnica, Cacalia, and Senecio. Additional counts from Arnica support our previous suggestion that x = 19 for this genus. It is assumed that observed meiotic irregularities are associated with apomixis in this genus. Basic chromosome numbers for various New World sections of Senecio are proposed, and certain problems of sectional relationships in this genus are discussed. Chromosome numbers and plant morphology of Cadiscus, Hulsea, and Whitneya indicate that these genera should be removed from Helenieae to Senecioneae. The possible affinity of the anomalous genus Adenocaulon with Mutisieae is discussed. Data presented in the paper further support our earlier proposal that the basic chromosome number for Senecioneae is x = 10.     

Opalinidae in African Anura. II. Genera Protozelleriella n. g. and Zelleriella

During 1988 and 1989, 409 specimens of southern African Anura, comprising 50 species in 9 families, were checked for opalinids in the cloaca. Protozelleriella devilliersi n. g., n. sp. was found in three of four Capensibufo rosei (Bufonidae); Zelleriella africana Sandon, 1938 in two of three Bufo angusticeps and one of 20 B. garmani (Bufonidae) plus three of 12 Phrynobatrachus natalensis, 12 of 19 Tomopterna cryptotis, seven of 14 T. delalandii, three of seven T. krugerensis and one of six T. natalensis (all Ranidae); Z. gambieri n. sp. in one of six T. natalensis; Z. garlandi n. sp. in two of six Kassina maculata (Hyperoliidae); Z. sandoni n. sp. in two of 20 B. garmani, two of six K. maculata, one of seven K. senegalensis and one of four Leptopelis mossambicus (Hyperoliidae) plus one of five Phrynomerus bifasciatus (Microhylidae) and two of 19 T. cryptotis. It is suggested that the Ranidae (in particular the genus Tomopterna) and the Hyperoliidae are among the major carriers of Zelleriella in the Afrotropical Region.     

Multiphase catalysis. II. Hollow fiber catalysts

A theory of diffusion control within hollow fiber catalysts is derived for three different types of coordinate geometries: Cartesian, cylindrical, and spherical. Effectiveness factors are calculated and formulas for reactant conversion in both a fixed-bed and a contimunuous-feed stirred-tank reactor are derived. The apparent Michaelis constant, K_m′, is a measure of the amount of diffusion control within the catalysts. When K_m′ is equal to K_m, the true Michaelis constant, there is no diffusion control. In all other cases K_m′ is greater than K_m. Hollow fibers are attractive alternatives to spherical microcapsules for the encapsulation of enzymes.     

Bulb-type onion introgressants posessing Allium fistulosum L. genes recovered from interspecific hybrid backcrosses between A. cepa L. and A. fistulosum L.

Allium fistulosum possesses a number of traits which would be desirable in A. cepa. Thus far, no commercial A. cepa cultivars have been released which harbor Allium fistulosum traits. F₁BC₃ populations were generated for this study by backcrossing A. cepa to A. cepa×A. fistulosum hybrids. The F₁BC₃ plants were evaluated for plant morphology, floral characters, male- sterile cytoplasm, soluble solids and pungency, and isozymes. Overall growth habit and floral characters of the F₁BC₃ plants were much like A. cepa. We report here the recovery of recombinant, bulbing, and fertile A. cepa-type onions that exhibit A. fistulosum isozyme alleles and morphological markers. Recombination between A. cepa and A. fistulosum genomes was achieved using the introgression strategy of backcrossing A. fistulosum into A. cepa, thereby ameliorating the nuclear cytoplasmic barriers that occurred in previous less successful introgression attempts when plants were not in A. cepa cytoplasm. We believe this report to be the first demonstration of onion introgressants that are like A. cepa in appearance, are male- and female-fertile, and possess A. fistulosum genes. Received: 29 May 1999 / Accepted 22 June 1999     

Helix-coiled transition in heteropolymers. I. Ground-state energy

A new technique is presented for treating the ground state of an heteropolymer with a random sequence of components. An exact system of equations is found for determining the ground state energy E which is equal to the polymer free energy f in the lowest-order approximation in T/V (V/2 is the large “surface” energy arising at the boundaries between coiled and “helical” sections: V ? T, U_k; U₁ and –U₂ are the free energies of the components counted from the corresponding coiled state energies). These equations are essentially simplified at certain fixed values of the ratio U₁/U₂. For integer values of U₂/U₁ and U₁/U₂ a solution is obtained with an accuracy exp(–V/U_k). The ground-state energy as a function of U₁ and U₂ is shown to be highly irregular: its derivatives have jumps at an infinite number of points. These jumps provide a fine structure of the melting curves. A smoothed over the jumps function E′ is found by way of analytic continuation from the integer values of U₁/U₂ and U₂/U₁. The accuracy of the approximation f ≈ E is estimated and the correctional term of order T/V is determined.     

Isothecium myosuroides var. brachythecioides (Dixon) Braithw. reinstated as a species,I. interludens Stirt.

The taxon currently known as Isothecium myosuroides var. brachythecioides (Dixon) Braithw. is reinstated as a species, I. interludens Stirt., the name originally assigned by Stirton when it was first described. The morphological characters separating I. myosuroides s.s. and I. interludens are summarised. The sporophytes of I. interludens, described here for the first time, differ in shape, and pattern of exothecial cells from those of I. myosuroides. A molecular analysis based on variation of the ITS region shows that I. holtii Kindb. and I. alopecuroides (Lam. ex Dubois) Isov. are not monophyletic, calling for a re-assessment of these species, whereas the monophyly of the other species, including I. interludens, cannot be rejected. The analysis failed, however, to yield molecular synapomorphies for I. interludens and other species within I. myosuroides s.l., which we interpret as the incomplete sorting of alleles among recently evolved species. Isothecium interludens is a European endemic with a hyperoceanic temperate distribution. Its nested position within a clade including the two Macaronesian endemics I. prolixum (Mitt.) M.Stech and I. montanum Draper, Hedenäs, M.Stech, T.Lopes & Sim-Sim is suggestive of a Macaronesian origin, in line with the idea that the European Atlantic fringe flora assembled during the course of the last interglacial from Macaronesian ancestors. Isothecium therefore offers a model of prime importance for the study of ongoing speciation in mosses.     

Validation of Hygrohypnum Lindb. sect. Dilatatae Szafr.

Abstract

A number of chemical habitat parameters for the species Scorpidium scorpioides, S. cossonii and S. revolvens were investigated in three areas in northern and southern Sweden. S. revolvens occurs in a much narrower range of some parameters, especially pH and conductivity, than the other two species. When pH and conductivity are considered together, S. revolvens and S. cossonii are almost completely mutually exclusive.     

CHROMOSOME NUMBERS IN COMPOSITAE. IV. AMBROSIEAE

New chromosome observations are reported for 30 species and varieties from 4 genera of Ambrosieae: Ambrosia (including Franseria), Diceria, Hymenoclea and Iva. Neither polyploidy nor aneuploidy is known in the genera Dicorea, Hymenoclea or Xanthium. Aneuplcid reduction appears to have played a role in the genome evolution of several species of Iva and Ambrosia. Polyploid species occur in both Iva and Ambrosia and polyploid series exist for at least 5 species or species aggregates of the latter. All available evidence indicates that the primitive chromosome number for the tribe is x = 18, differentiation and speciation having occurred at this level, which is here termed diploid. The group, however, must ultimately have been of polyploid origin from forms with x = 9.     

Growth and reproduction of three cladoceran species from a small wetland in the south-eastern U.S.A.

SUMMARY 1. Growth, reproduction and life‐history parameters were measured for three cladoceran species from a small south‐eastern wetland, U.S.A. Simocephalus serrulatus, Diaphanosoma brachyurum and Scapholeberis mucronata juveniles were reared at temperatures between 10 and 25 °C on natural food resources. 2. Growth rate increased with temperature and decreased with individual size for all three species. Maximum somatic growth rate was higher for Simocephalus (49–72% day^?1) and Diaphanosoma (21–91% day^?1) than for Scapholeberis (11–45% day^?1). Multiple regression equations were developed which predict temperature‐ and mass‐specific growth rates for each species. 3. Scapholeberis egg production was positively related to temperature; however, maximum egg production occurred at intermediate temperatures for Simocephalus and Diaphanosoma. Mean cumulative egg production was higher for Scapholeberis (28–92 eggs per female) than for Simocephalus (18–25 eggs per female) and Diaphanosoma (1–41 eggs per female), and was related to differences in reproductive strategy and survival. 4. Survival was inversely related to temperature in most cases. For all three cladocerans, the intrinsic rate of increase (r) and net reproductive rate (R₀) increased with temperature, whereas generation time (G) decreased. Greater egg production by Scapholeberis compared with the other two cladocerans was consistent with higher R₀ values for Scapholeberis at any given temperature. Although r was very similar among species, G was typically longer for Scapholeberis than for Simocephalus and Diaphanosoma. 5. This analysis provides basic information about the population parameters of these coexisting wetland species, and the growth rate models can be applied to field data to determine production dynamics.     

Analyses of Phaseolus vulgaris L. and P. coccineus Lam. hybrids by RFLP: preferential transmission of P. vulgaris alleles

Summary Restriction fragment length polymorphism (RFLP) was determined among P. vulgaris genotypes and Phaseolus species using 19 probes. The incidence of polymorphism was high (70–86%) between species, but relatively low (22–26%) between genotypes of P. vulgaris. Suitable probes were identified for the analysis of P. vulgaris and P. coccineus hybrids. The segregation pattern in F₂ populations was Mendelian for two probes (LHB and VEE20) and non-Mendelian for GS-g, CHS, and CHI. Statistical analyses indicated gametic selection with preferential transmission of the P. vulgaris alleles, which may account for the selective recovery of P. vulgaris progeny types observed earlier. The available hybrids of P. vulgaris and P. coccineus and the high degree of interspecific RFLP will facilitate the construction of a linkage map for Phaseolus.     

Kinetics of formation of fibrin oligomers. I. Theory

The course of formation of fibrin oligomers is treated theoretically for the condition that self-assembly of fibrin monomers is rapid compared with the loss of A peptides by the enzymatic action of thrombin. The rate constant for removal of the second A peptide is taken to be larger than that for the first by an arbitrary factor q; the association of activated A sites with their complementary a sites is assumed to be random and independent of oligomer size. Two types of oligomers are considered: noncovalently bonded protofibrils formed by the staggered overlap of thrombin-activated monomers and covalently bonded linear oligomers formed by factor XIIIa-mediated end-to-end ligation of adjacent monomers within protofibrils. Oligomers of the first type, if ligated, are dissociated to oligomers of the second type by solubilization in SDS–urea. Theoretical curves are presented for x _w and x ′_w (weight-average degree of polymerization of staggered overlap and linear ligated oligomers, respectively) and for the weight fractions of monomer, dimer, and decamer of both ligated and unligated species as functions of y, the fraction of A peptide removed; and also for w_x and w′_x, the weight fractions of x-mer of the respective oligomer types, as a function of x at y = 0.5. With increasing q, the maximum w_x or w′_x that a low oligomer will reach during the reaction decreases and the size distribution is broadened toward larger oligomers. Comparison with experiment is made in a companion paper.     

Four novel yeasts from decaying organic matter: Blastobotrys robertii sp. nov., Candida cretensis sp. nov., Candida scorzettiae sp. nov. and Candida vadensis sp. nov

Four novel yeast species are described, two from decaying mushrooms, viz. Candida cretensis and Candida vadensis, and two from rotten wood, viz. Blastobotrys robertii and Candida scorzettiae. Accession numbers for the CBS and ARS Culture Collections, and GenBank accession numbers for the D1/D2 domains of the large subunit of ribosomal DNA are: B. robertii CBS 10106^T, NRRL Y-27775, DQ839395; C. cretensis CBS 9453^T, NRRL Y-27777, AY4998861 and DQ839393; C. scorzettiae CBS 10107^T, NRRL Y-27665, DQ839394; C. vadensis CBS 9454^T, NRRL Y-27778, AY498863 and DQ839396. The GenBank accession number for the ITS region of C. cretensis is AY498862 and that for C. vadensis is AY498864. C. cretensis was the only species of the four that displayed fermentative activity. All four type strains grew on n-hexadecane. C. scorzettiae is the only one of the new species that assimilates some phenolic compounds, viz. 3-hydroxy derivatives of benzoic, phenylacetic and cinnamic acids, but not the corresponding 4-hydroxy acids. This is indicative of an operative gentisate pathway.     

Molecular evidence for hybrid origin of Quercus crenata Lam. (Fagaceae) from Q. cerris L. and Q. suber L.

Abstract

Random Amplified Polymorphic DNA (RAPD) and Inter-Simple Sequence Repeats (ISSR) markers were employed to examine samples from Quercus cerris, Q. suber and Q. crenata in order to test the hypothesis of the hybrid origin of Q. crenata from Q. cerris and Q. suber in a part of its distribution area where the two putative parents do not overlap at present. Leaves from 21 Q. crenata and 37 Q. cerris individual trees were collected at natural sites in northern Italy, where Q. suber is currently lacking; 21 Q. suber and six Q. crenata plants from central Italy were also analysed. Results from Unweighted Pair Group Method with Arithmetic mean (UPGMA) analysis and principal component analysis (PCA) implied that exchange of neutral markers has been considerable between the three species, while differences in morphological characters have remained comparatively stable. The Mantel test indicated low correlation between RAPD- and ISSR-based similarity matrices, showing that the two screening techniques reveal unrelated estimates of genetic relationships. Hybrid indices computed for both markers displayed an intermediate position of Q. crenata individuals between the two putative parents shifted toward Q. cerris. Results from the present study corroborate the hypothesis of a hybrid origin for Q. crenata occurring in northern Italy, and suggest asymmetrical backcrossing with Q. cerris acting as the recurrent parent.     

Miliusa cambodgensis sp. nov. (Annonaceae) from Cambodia and M. astiana,M. ninhbinhensis spp. nov. from Vietnam

The genus Miliusa in Cambodia and Vietnam is reviewed. Cambodia and Vietnam each harbors six species of Miliusa, including three which are described as new to science: one from Cambodia (Miliusa cambodgensis sp. nov.), the other two from Vietnam (M. astiana and M. ninhbinhensis spp. nov.). In addition, a complete nomenclature and relevant information about the Miliusa species previously known from Cambodia and Vietnam are provided, including keys to the Cambodian and Vietnamese species, the designation of a lectotype for M. baillonii and the synonymization of M. balansae var. elongatoides, M. chunii and M. sinensis with M. balansae.     

Leaf breakdown in a regulated desert river: Colorado River, Arizona, U.S.A.

We compared processing rates (k _d) for leaves of the native willow (Salix exigua Nutt.) and cottonwood (Populus fremontii Wats.) to those of the non-native salt cedar (Tamarix chinensis Lour.) in the regulated Colorado River, U.S.A. Leaf packs of each species were incubated at Lees Ferry, approximately 26 km below Glen Canyon Dam, Arizona. Leaf packs were processed at 2, 21, 46, 84 and 142-d intervals. Water temperatures remained relatively constant (10 °C, SE ± 1 °C) during the study. There were significant differences in processing rates between species, with P. fremontii showing the fastest breakdown. After 142 d, only 20% of the P. fremontii leaf mass remained, whereas 30% and 52% of leaf masses remained for T. chinensis and S. exigua, respectively. The k _d value for P. fremontii was 0.0062 compared to 0.0049 and 0.0038 for T. chinensis and S. exigua, respectively. Invertebrate colonization was not significantly different between native and non-native plant species with oligochaetes the most abundant animal colonizing the leaf packs. Dual stable isotope analysis showed that leaf material was not the primary food for invertebrates associated with leaf packs. Processing rates for all leaf types were slow in the regulated Colorado River compared to rates reported in many other systems. This is likely due to the lack of caddisfly and stonefly shredders and perhaps slow metabolic rates by microbes.     

Comparative studies on the effect of vitamins on sporulation in Fusarium oxysporum schlecht. ex. Fr. and Fusarium moniliforme V. subglutinans Wr. & Rg.

On the basis of sporulation (total output of all the three spore forms taken together) and fungal mat production bothF. oxysporum Schlecht ex.Fr. andF. moniliforme v.subglutinans Wr. &Rg. are auxoheterotrophic for thiamine, biotin, inositol, riboflavin and pyridoxine. The first three vitamins are selective in accelerating macro-conidial production also inF. moniliforme, which otherwise shows decrease with advance in days of incubation.F. moniliforme is an auxo-autotroph for nicotinic acid, Ca-pantothenate and folic acid and auxoheterotroph for ascorbic acid. Auxoautotrophy for Ca-pantothenate, folic acid, l-ascorbic acid and p-aminobenzoic acid cannot be suggested forF. oxysporum. Whereas nicotinic acid is a depressent of sporulation inF. oxysporum, inF. moniliforme another vitamin p-aminobenzoic acid depresses sporulation. As the two species ofFusarium show differences in preference as well as inhibition to at least five of the vitamins studied and also varied trends of pH changes exists there is full justification for their separate taxonomic placements.     

CHROMOSOME NUMBERS IN COMPOSITAE. X.

Reports of 126 new counts are recorded for 9 tribes of Compositae, including reports for 45 genera and 102 species. Six genera, Psilocarphus (n = 14). Relhania (n = 7), Rutidosis (n = 9), Chaetanthera (n = 14), Hecastocleis (n = 8), and Hesperomannia (n = 10), and 41 species were previously unreported.     

Relationships among Cratoneuron curvicaule,C. filicinum var. filicinum,and C. filicinum var. atrovirens (Bryophyta: Amblystegiaceae)

Abstract

The relationships among western Eurasian and Macaronesian Cratoneuron filicinum (Hedw.) Spruce var. filicinum, C. filicinum var. atrovirens (Brid.) Ochyra, and C. curvicaule (Jur.) G.Roth were explored by ITS and the chloroplast markers rpl16 and tRNA-Gly. Haplotype networks, Jacknife, and Neighbour joining trees all provide high support for the recognition of C. curvicaule as distinct from C. filicinum, whereas the two varieties of the latter could not be distinguished. It is concluded that C. filicinum var. atrovirens most likely represents a phenotypic modification of C. filicinum that occurs especially in certain submerged environments or under heavily dripping water. The maximal support for the Cratoneuron clade and the small and quantitative morphological differences between its two species are arguments for not splitting this genus.