The colonization of two new brackish water habitats on the isle of Texel (the Netherlands)

Summary As a result of the reconstruction of a dike on the Dutch island of Texel two small areas of the Wadden Sea were embanked in 1977 and 1978. In 1981 both by now blocked brackish waters were investigated for macrofauna and macroflora. The vegetation on these former parts of the Wadden Sea was still in a colonizing state. Many small patches ofRuppia spp. were found, contrary to older brackish waters with more extendedRuppia beds. The striking dominance ofR.maritima agrees with its large seed production enabling to colonize quickly new areas. In one of the ponds, where the maximum salinity of 23 Cl^– exceeded far the tolerance limit of this species given in the literature (15 Cl^–),R.maritima was still more numerous thanR.cirrhosa, a species which is more tolerant to salinity fluctuations. Several years after isolation these areas are still inhabited by a few Wadden Sea macrofauna species (e.g. Carcinus maenas, Hydrobia ulvae andCapitella capitata) who managed to survive the drastic environmental changes. In addition, a large number of species characteristic for blocked brackish waters has already colonized the new ponds. One of the two, that has always completely been isolated from other inland water, was inhabited in 1981 by 13 brackish water species. In the future the two new ponds on Texel are expected to loose their pioneer characteristics. There are reasons to expect that most of the Wadden Sea macrofauna relics will soon become extinct. A more extendedRuppia vegetation will probably develop together with a relative increase ofRuppia cirrhosa.     

Evolution of thedec-1 eggshell locus inDrosophila. I. Restriction site mapping and limited sequence comparison in themelanogaster species subgroup

Summary We have analyzed 18 kb of DNA in and upstream of thedefective chorion-1 (dec-1) locus of the eight known species of themelanogaster species subgroup ofDrosophila. The restriction maps ofD. simulans, D. mauritiana, D. sechellia, D. erecta, andD. orena are shown to have basically the restriction map ofD. melanogaster, whereas the maps ofD. teissieri andD. yakuba were more difficult to align. However, the basic amount of DNA and sequence arrangement appear to have been conserved in these species. A small deletion of varying length (65–200 bp) is found in a repeated sequence of the central transcribed region ofD. melanogaster, D. simulans, andD. erecta. Restriction site mapping indicated that thedec-1 gene is highly conserved in themelanogaster species subgroup. However, sequence comparison revealed that the amount of nucleotide and amino acid substitution in the repeated region is much larger than in the 5 translated region. The 5 flanking region showed noticeable restriction site polymorphisms between species. Based on calculations from the restriction maps a dendrogram was derived that supports earlier published phylogenetic relationships within themelanogaster species subgroup except that theerecta-orena pair is placed closer to themelanogaster complex than toD. teissieri andD. yakuba.     

Phylogeny and habitat adaptations within a monophyletic group of wetland moss genera (Amblystegiaceae)

Genus level phylogenetic patterns within a monophyletic group of wetland mosses consisting ofTomentypnum, Hamatocaulis, Scorpidium, Conardia, Calliergon, Warnstorfia, Straminergon, andLoeskypnum (Amblystegiaceae) are cladistically analysed, usingPalustriella and partlyCratoneuron as outgroups. The ingroup consists of two clades, one withTomentypnum, Hamatocaulis andScorpidium, the other with the other ingroup genera. The second clade gets completely resolved only with the inclusion of habitat data. The adaptation to relatively dry wetland habitats probably evolved in the ancestor ofStraminergon andLoeskypnum, the species ofCalliergon andWarnstorfia, which are more ancestral, growing in wetter habitats. The more primitive taxa of the ingroup, as well asPalustriella species, occur in relatively mineral-rich habitats and adaptations to poorer habitats occurred several times in the two clades.     

Alkaloids of theSedum acre-group (Crassulaceae)

The 16 species of theSedum acre-group were investigated for the presence of alkaloids. They areS. acre ofS. ser.Acria, S. alpestre, S. annuum, S. apoleipon, S. borissovae, S. euxinum, S. grisebachii, S. laconicum, S. multiceps, S. sexangulare, S. tuberiferum, S. tuberosum, S. ursi, andS. urvillei ofS. ser.Alpestria, S. samium ofS. ser.Samia, andS. litoreum ofS. ser.Litorea. S. acre differs significantly from the other species. It contains sedamine, hydroxy sedamine, and a number of 2,6-disubstituted piperidine alkaloids. The leafy parts of the species ofS. ser.Alpestria, S. ser.Samia, andS. ser.Litorea contain 4 piperidine alkaloids which also occur inS. acre, and in addition 4 pyrrolidine alkaloids not present inS. acre. The composition of the alkaloid fraction agrees with the infrageneric classification (series) based on the hybridization patterns of the species (comparia).     

A short note onLecane species (rotifera) found inUtricularia minor vegetation

Summary InUtricularia minor vegetation a number ofLecane spp. are found. Remarks are made regarding confusion resulting from the use of VOIGT's keys. L.glypta is a synonym ofL.flexilis; L. lunaris andL.constricta belong to the species group L.lunaris andL.sinuata is a form ofL.hamata; L.hamata f.sinuata is new to the European fauna.     

Tolerance and Resistance in Gastropod Mollusks Hydrobia ulvaeand H. ventrosafrom the White Sea to Abiotic Environmental Factors

Tolerance to salinity changes and resistance to desiccation, fresh water, and freezing were studied in two hydrobiid species from the White Sea, Hydrobia ulvae(Pennant) and H. ventrosaMontagu. It was shown that H. ventrosahas a greater tolerance to low salinities in the range of 6–10 but is less tolerant to high salinities (35–45). The interspecies differences in low salinity tolerance persisted after the acclimation of snails to 20, 16, and 12. A comparison of survival in fresh water and under desiccation conditions suggests that H. ulvaeis more resistant to these factors. In fresh water, LT₅₀was 30 and 60 days for H. ventrosaand H. ulvae, respectively. Under desiccation conditions, LT₅₀was 6 and 25 days for H. ventrosaand H. ulvae, respectively. At subzero temperatures, H. ventrosawas shown to be a superior survivor. Within the same species of mud snail, the detrimental effect of freezing depended on the salinity: survival decreased with decreasing salinity. These data suggest significant differences in the mechanisms of resistance and tolerance to abiotic environmental factors between the two species. Despite the partial overlapping of their ecological niches, the interspecies differences may play an important role in the distribution and spatial structure dynamics of coexisting populations of these species in the White Sea region.     

Vesicular-arbuscular mycorrhizal fungi in coastal dune plant communities II. Spore formation ofGlomus spp. predominates under geographically separated patches ofElymus mollis

Five study sites in Japan with pure patches ofElymus mollis near to the shoreline were chosen. Abundance of spore formation ofGlomus spp. underE. mollis patches were studied at four sites to understand the factors determining the development of VA mycorrhizal fungal communities at the edge of coastal sand dune vegetation. At each study site, eight soil samples from two soil depths were collected four times (three times for Niigata) during a year. Spores ofGlomus spp. predominated at every site, but species composition ofGlomus spp. differed from site to site. In a further experiment to measure the soil depth of the highest spore densities underE. mollis, the highest density was found at depths where rhizomes ofE. mollis were present.Contribution No. 119, Laboratories of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Globin evolution in the genusXenopus: Comparative analysis of cDNAs coding for adult globin polypeptides ofXenopus borealis andXenopus tropicalis

Summary Globin mRNAs ofXenopus borealis andXenopus tropicalis have been cloned and sequenced. The nucleotide and derived amino acid sequences were compared with each other and with already available data fromXenopus laevis. This analysis rendered clear evidence that the common ancestor ofX. laevis andX. borealis, but not ofX. tropicalis, had lost one amino acid of the -globins prior to a genome duplication event that preceded the segregation of the former two species. Replacement-site substitutions were used to calculate a rough time scale of genome duplication and species segregation. The results suggest an ancient separation between theX. laevis and theX. tropicalis groups occurring approximately 110–120 million years ago. Analysis of the amino acid chains demonstrated various alterations. However, some functional domains, like heme-binding sites and₁₂ contact sites, were subject to a high degree of conservation, indicating the existence of functional constraints on them also in the genusXenopus.     

Fruiting studies in species ofCapronia (Herpotrichiellaceae)

A recently described protocol for thein vitro production of ascomata was employed to determine the sexual incompatibility systems of five species ofCapronia. The formation of mature ascomata in isolates derived from single ascospores demonstrated thatC. epimyces, C. mansonii, andC. munkii n. sp. are homothallic. In contrast, fertile ascomata were observed only in mass-ascospore isolates and pairwise crosses between specific single-ascospore isolates inC. dactylotricha n. sp. andC. moravica. TheExophiala anamorphs ofC. dactylotricha andC. munkii are described and aPhialophora-like synanamorph is reported for the former species. Germinating ascospores ofC. munkii formed conidiogenous cells directly, while the ascospores of the remaining species germinated to produce germ tubes and hyphae. The application of the terms microcyclic conidiation to secondary conidium production and sclerotial body and stroma to the multicellular structures produced by species ofCapronia andExophiala are discussed.     

Teliospores of smut fungi teliospore walls and the development of ornamentation studied by electron microscopy

Summary The walls of mature teliospores and the development of ornamentation, as seen by transmission electron microscopy, are described for 37 genera of smut fungi, based on observations of ca. 120 species and on literature. Structural diversity of mature teliospore walls is due to differences in spore wall layers forming the spore wall (endosporium, middle layer, exosporium, ornamentation) and to different elements forming the ornamentation (exosporium, ornaments, sheath, hyphal wall, adjacent fungal cells, material of the host). During teliosporogenesis the outer layers are usually deposited first. At the beginning of the formation of the ornamentation the plasma membrane may be smooth or undulated carrying the developing ornaments on its tips or in its depressions. The ornamentation of some genera appears similar when seen by scanning electron microscopy, but can be the product of different developmental patterns (e.g., warts of species ofFarysia, Tilletia, andUstilago), however, warty and reticulate ornamentation can both be produced by similar developmental processes (shown, e.g., for species ofCintractia andTilletia). Typical structures of the mature teliospore wall and developmental patterns based on homologous similarities are described for the following groups of genera or species:Macalpinomyces, Melanopsichium, Sporisorium, andUstilago infecting members of the family Poaceae;Kuntzeomyces, Testicularia, andTrichocintractia; Anthracoidea, Cintractia, Heterotolyposporium piluliforme, andTolyposporium junci; Glomosporium, Sorosporium, andThecaphora; Conidiosporomyces, Erratomyces, Ingoldiomyces, Neovossia, Oberwinkleria, andTilletia; Entyloma, and genera of the Doassansia group;Liroa, Microbotryum, Sphacelotheca, Ustilago infecting dicotyledons, andZundeliomyces; Aurantiosporium, Fulvisporium, andUstilentyloma. Special characteristics of the teliospore wall were observed for the generaDermatosorus, Doassinga, Entorrhha, Farysia, Mycosyrinx, Rhamphospora, and some species ofTolyposporium.Part 165 in the series Studies in Heterobasidiomycetes from the Botanical Institute, University of Tübingen     

Vesicular-arbuscular mycorrhizal fungi in coastal dune plant communities I. Spore formation ofGlomus spp. predominates under a patch ofElymus mollis

Vesicular-arbuscular (VA) mycorrhizal fungi in pure patches of coastal dune plantsElymus mollis, Wedelia prostrata andZoysia macrostachya were examined for frequency of occurrence and number of spores of VA mycorrhizal fungi over one year. Six species in three genera of VA mycorrhizal fungi were recovered. Under a patch ofE. mollis, spores ofAcaulospora sp. 1,Glomus tortuosum, Glomus sp. 1,Glomus sp. 2 andScutellospora gregaria were recovered. Spores ofGlomus spp. were most common. In patches ofW. prostrata andZ. macrostachya spores ofAcaulospora sp. 1,G. tortuosum, Glomus sp. 1,Glomus sp. 2,S. gregaria andScutellospora sp. 1 were found.Contribution No. 112, Laboratories of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Endopolyploidization patterns in non-generative antheridial cells in mono- and dioeciousChara spp. (Characeae) with different DNA C-values

Cytophotometric measurements of nuclear DNA contents and morphometric analyses in the antheridia of five species ofChara indicate that the level of endopolyploidy plays an important role in determining the maximum sizes that shield cells, manubria, and capitular cells attain at the final stage of spermiogenesis. Dioecious species with low DNA C-values—C. aspera andC. tomentosa—display higher values of endopolyploidy: their male sex organs are larger and the quantities of spermatozoids per antheridium are greater than those estimated for monoecious species—C. vulgaris, C. fragilis, andC. contraria. Two types of nucleotypic effects were found to synchronize developmental traits in germ line cells and non-generative component parts within the antheridia; both are discussed in relation to the biological productivity of male sex organs in mono- and dioecious species ofChara.     

Comparative studies on the teliospore morphology and ontogeny ofSpumula serispora,spec. nova,andRavenelia texensis (Uredinales,Raveneliaceae)

A new rust fungus,Spumula serispora, is described. The morphology of the teliospores and the telia was studied. In the teliospores ofS. serispora andS. quadrifida, the type species of the genus, sterile cells could be found, which are comparable to apical cells of otherRaveneliaceae. Similar sterile cells were also present in the telial heads ofRavenelia texensis. The ontogeny of the teliospores ofS. serispora and the teliospore heads ofRavenelia texensis was studied and compared. In both species the ontogeny of the spores heads was similar. InR. texensis hygroscopic cysts sustaining the spore heads were produced by division and not by conversion of basal sterile cells of the teliospore heads.Part 114 of the series Studies inHeterobasidiomycetes.     

Experimental hybridization between catfishes of the families Clariidae and Pangasiidae in Thailand

Synopsis Hybrids between the clariid speciesClarias macrocephalus andC. batrachus and the pangasiid speciesPangasius sutchi were obtained by hormone injection of brood stock and artificial fertilization. Pure parental crosses as well as all possible hybrid combinations were obtained. Fertility, hatchability, and post-yolk absorption survival was high (66–99%) in all pure parental crosses and in all crosses between the two species ofClarias. In crosses betweenClarias andPangasius fertilization was also very high (68–97%) but hatchability varied from 11 to 23% and post-yolk absorption survival from 0% inPangasius sutchi ×Clarias batrachus to about 50% inPangasius sutchi ×Clarias macrocephalus . The longest-lived hybrids ofPangasius andClarias were those ofPangasius sutchi ×Clarias macrocephalus which survived until the experiment was prematurely terminated due to contaminated food after 4 1/2 months, at which point they had grown to total lengths of 8–14cm. The hybrids comprised four morphotypes, two relativelyPangasius-like and two relativelyClarias-like, but all markedly different from the parental species.     

Seasonal variation of arbuscular mycorrhizal fungi in temperate grasslands along a wide hydrologic gradient

We studied seasonal variation in population attributes of arbuscular mycorrhizal (AM) fungi over 2 years in four sites of temperate grasslands of the Argentinean Flooding Pampas. The sites represent a wide range of soil conditions, hydrologic gradients, and floristic composition. Lotus glaber, a perennial herbaceous legume naturalised in the Flooding Pampas, was dominant at the four plant community sites. Its roots were highly colonised by AM fungi. Temporal variations in spore density, spore type, AM root colonisation, floristic composition and soil chemical characteristics occurred in each site and were different among sites. The duration of flooding had no effect on spore density but depressed AM root colonisation. Eleven different types of spores were recognized and four were identified. Two species dominated at the four sites: Glomus fasciculatum and Glomus intraradices. Spore density was highest in summer (dry season) and lowest in winter (wet season) with intermediate values in autumn and spring. Colonisation of L. glaber roots was highest in summer or spring and lowest in winter or autumn. The relative density of G. fasciculatum and G. intraradices versus Glomus sp. and Acaulospora sp. had distinctive seasonal peaks. These seasonal peaks occurred at all four sites, suggesting differences among AM fungus species with respect to the seasonality of sporulation. Spore density and AM root colonisation when measured at any one time were poorly related to each other. However, spore density was significantly correlated with root colonisation 3 months before, suggesting that high colonisation in one season precedes high sporulation in the next season.     

Studies of protoplast culture and plant regeneration from commercial and rapid-cyclingBrassica species

Protoplasts were isolated from aseptic shoot cultures of commercial cultivars ofBrassica napus, B. oleracea andB. campestris, and from the six rapid-cycling brassica species. Of the rapid-cycling species, onlyB. napus responded well to the culture conditions used; 2% of protoplasts formed calli and up to 5% of calli regenerated shoots. Regeneration was also achieved from commercial cultivars ofB. napus andB. oleracea. For these two species the plating density, time of dilution with fresh medium and the composition of the shoot-inducing medium were all found to have an important influence on the efficiency of plant regeneration. Both responded better to maltose than to sucrose-based media. Under the optimum conditionsB. napus showed a plating efficiency of 7.8% and shooting efficiency of 17%; forB. oleracea the figures were 2% and 56%, respectively.Abbreviations BAP 6-benzylaminopurine - NAA -naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid     

Pyrolysis mass spectrometry characterisation and numerical taxonomy ofAeromonas spp.

Reference strains (2) and 29 isolates ofAeromonas spp. from clinical material and environmental specimens were characterised in traditional biochemical tests, and in pyrolysis mass spectrometry, which gives data reflecting whole-cell composition. Numerical taxonomic analyses of the data sets were compared with conventional identification at species level, and pathogenic potential, as inferred from the origin of the isolates. Clustering with conventional test reaction patterns showed, for each of the species represented, a clearly defined core group of typical isolates, surrounded by a halo of aberrant strains. One further cluster comprised strains intermediate betweenA. caviae andA. hydrophila, and one strain was grossly atypical in both analyses. Clustering from pyrolysis data corresponded less well with species identification. Broadly, the biochemical division between core and halo strains was supported in pyrolysis forA. caviae andA. sobria, but the main group ofA. hydrophila in pyrolysis comprised strains clustering in the core and halo groups of this species, and three strains intermediate betweenA. hydrophila andA. caviae in biochemical tests. Two further pyrolysis clusters comprised core and halo strains ofA. hydrophila. However, pyrolysis clustering correlated well with inferred pathogenicity, showing four clusters of probable pathogens, six clusters of probable nonpathogens, and one two member cluster of doubtful status. Most strains that clustered in the species haloes, or in species-intermediate groups in biochemical tests, were non-human isolates, or were isolated in the absence of symptomatic infection. The correlation of inferred pathogenicity with biochemical clustering was poorer than that with pyrolysis clustering.Abbreviations CTRP conventional test reaction pattern - PyMS pyrolysis mass spectrometry     

Temporal and spatial distribution of chironomid larvae and oligochaetes in two Dutch storage reservoirs

Long-term changes in distribution and taxonomic composition of chironomid larvae and oligochaetes in two water storage reservoirs in The Netherlands were studied. A succession among the chironomid species was observed. In the last 10–15 years chironomid densities varied. Compared with other lakes chironomid densities were high. Densities of chironomids were higher in the littoral zone than in the profundal zone. The opposite was found for oligochaetes. Densities and composition of the chironomid fauna in the two reservoirs were similar.Procladius, Tanytarsus andHarnischia dominated at all depths. However, pupal exuviae samples showed some differences in chironomid taxonomic composition between the two reservoirs. Orthocladiinae, rarely found in bottom samples, abounded in pupal exuviae samples.     

In vitro physiological approach to classification ofFrankia isolates of ‘the Alnus group’, based on urease,protease and β-glucosidase activities

Summary Most of theFrankia strains isolated fromAlnus andMyrica species are morphologically almost indistinguishable, when grown under standard culture conditions. They form similar vegetative hyphae while sporangia are produced in variable amounts from strain to strain.Physiological reactions were assessed in order to compare 20 strains isolated from various species ofAlnus and one species ofMyrica in Europe and North America. Among invariant negative or positive characteristics, differences in urease, protease and -glucosidase activities appeared to be of significant value.     

Differential abundance of simple repetitive sequences in species ofBrassica and relatedBrassicaceae

SixBrassica species, known as the triangle of U, and four species from related genera were characterized by DNA fingerprinting with simple repetitive oligonucleotide probes. Our results show that CT-, TCC-, and GTG-repeat motifs are equally abundant in the genomes of the sixBrassica species. In contrast, GATA-, GGAT-, and GACA-multimers are unevenly distributed among different species. As judged from the number and strength of hybridization signals, the highest copy number of all three motifs occurs inBrassica nigra, while the lowest is observed inB. oleracea. The abundance of GATA-and GACA-repeats varies in a coordinate way. The amphidiploid genomes ofB. juncea, B. carinata, andB. napus each harbour intermediate amounts of (GATA)₄ and (GACA)₄-detected repeats as compared to their diploid progenitors, thus supporting the concept of the U triangle. GATA-, GACA-, and GGAT-repeats were also abundant inEruca sativa andSinapis arvensis, but not inRaphanus sativus andSinapis alba. These results support the idea thatBrassica nigra is more closely related toSinapis arvensis than to otherBrassica species such asB. rapa andB. oleracea.