Effects of xylem sap flow on carbon dioxide efflux from stems of birch (Betula pendula Roth)

The effect of xylem sap flow in stems of mature Betula pendula Roth on radial CO₂ efflux was studied from April to October 2001. Temperature-controlled respiration cuvettes allowed measurements of CO₂ efflux without interference from temperature gradients between stem surface and sapwood. Variations of sap flow in different stem sectors, and in a given sector at different heights were analysed. Daytime reduction of CO₂ efflux caused by sap flow was expressed as the difference between gross and apparent CO₂ release. Gross CO₂ release was calculated from Arrhenius-equations derived from night-time data records of the same day, which were free from interference by sap flow. In mid-July, daytime reductions of CO₂ efflux reached 1.8–3.9 μmol CO₂ m⁻² g⁻¹ xylem sap transpired. Assuming tree-specific maximum transpiration rates of 30 kg H₂O d⁻¹ this is up to 40% of gross CO₂ release. In relation to photosynthetic CO₂ fixation the endogenous supply of dissolved CO₂ to the leaves acccounted for 0.5–3.7%. This study indicates a negative correlation between sap flow velocity and radial CO₂ efflux from B. pendula stems. Periods of unbalanced CO₂ partial pressures between aqueous and gaseous pathways during increase and decrease of sap flow seem to affect gaseous CO₂ release through lenticels. It is concluded that CO₂ efflux rates are not simply equivalent to respiration rates because of the interference of aqueous CO₂ transport by xylem sap flow in the wood-body of trees.     

Origin of the subgeneraCyclampterium, Paralampterium andSciadiopeplus fromLophocyrtis (Lophocyrtis) (Radiolaria, Theoperidae)

Work on the exceptionally well-preserved, rapidly accumulating Bath Cliff Section, Barbados and supplementary Deep Sea Drilling Project samples, has revealed the evolutionary origins of three stratigraphically useful species in theCryptoprora ornata Zone straddling the Eocene/Oligocene boundary and demonstrated the origin of the genusCyclampterium. Elucidation of the origin ofCyclampterium milowi necessitates a revision of the generaLophocyrtis andCyclampterium.Lophocyrtis (Lophocyrtis)jacchia is the ancestor ofL. (Cyclampterium)hadra, the earliest member in the subgenusCyclampterium which comprises the anagenetic lineage leading fromL. (C.)hadra toL. (C.)neatum. The monotypic subgenusSciadiopeplus branches off from an early member in theCyclampterium lineage. The new speciesL. (L.)exitelus andL. (S.)oberhaensliae terminate the subgeneraLophocyrtis andSciadiopeplus, respectively. During the investigation it also became clear that morphotypes resembling earlyL. (C.)milowi could be found in mid and high latitude assemblages in the late Early and late Middle Eocene. The origin of one these morphotypes was also traced toL. (Lophocyrtis)jacchia giving rise to the new subgenusParalampterium. This lineage includes the new speciesL. (Paralampterium)dumitricai and two species questionably assigned to it,L. (Paralampterium)?longiventer and the new speciesL. (Paralampterium) ?galenum. The relationship ofL. (P.)dumitricai toL. (P.) ?longiventer andL. (P.) ?galenum is unknown.     

Die Schneefinken (GattungenMontifringilla undLeucosticte)

Ohne Zusammenfassung     

Plantlet differentiation in leaf and root cultures of birch (Betula Pendula roth.)

The newly-formed leaves on plantlets differentiated from shoot bud cultures of Betula pendula, when excised and grown on a fresh medium produced callus from the margins or regenerated leafy shoots, roots and plantlets. After 4 weeks, upon transfer to murashige and Skoog (MS) medium supplemented with 3-indoleacetic acid (IAA) + 6-(4-hydroxy-3-methyl-trans-2-enyl)aminopurine (zeatin) + 6-aminopurine (adenine), 15–20 plantlets were produced from each explant. Likewise, the roots also showed meristematic activity at several sites, and produced nodulated callus on MS + α-naphthaleneacetic acid (NAA) + 6-(3-methyl-2-butenyl-amino)purine (2-iP) + adenine, and ultimately differentiated plantlets. Anatomical studies showed that initiation of callus takes place by meristematic activity in epidermal cells of leaves, and cortical cells of roots. Cytological investigations revealed no change in chromosomal complement.     

Predation by Callinectes sapidus (Rathbun) within Spartina alterniflora (Loisel) marshes

This study examined predation by the blue crab, Callinectes sapidus Rathbun, within intertidal Spartina alterniflora (Loisel) marshes of Dauphin Island, Alabama. Species and size preferences displayed by the predator when foraging within the marsh were investigated using nektonic, epifaunal, and infaunal prey populations including Fundulus similis Baird and Girard, Littorina irrorata Say, and Geukensia demissa Dillwyn.

Short-term field experiments involving the use of predator inclusion cages, in which the relative abundances of all prey species and the density of macrophyte vegetation were manipulated, indicated that mean mortality differed significantly among species. Blue crabs exhibited a distinct species preference for Littorina, and to a lesser extent, for Fundulus. However, the predator rarely choses infaunal individuals. Within predator inclusion cages, size selection by the crabs among three size classes of each prey was evident for Littorina and Fundulus but not for Geukensia. Blue crabs tended to select intermediate-sized snails and large fish while not exhibiting a size preference for infaunal bivalves.

In the marsh, mean percentage of the Littorina population within the 14–18 mm size class exhibited an increased mortality as compared to two other size classes, which was negatively correlated with increasing tidal height. Such a relationship may have been due to a decreasing gradient of crab predation associated with increasing tidal height. Geukensia size class distributions showed little evidence of differences along the tidal height gradient. No data are available for Fundulus, a mobile species which would not experience such differential predation along a marsh gradient.

In comparing crab predation patterns among prey species, it is apparent that Callinectes utilizes prey species differentially. Such differential utilization may be based on optimization of energy yield and minimization of energy expenditure. Thus, the preference of blue crabs for nektonic and epifaunal prey is hypothesized to be the result of a smaller energy expediture as a result of the crab's visual evaluation of these prey. Infaunal prey species (e.g., Geukensia) require a greater energy investment because of the necessity of excavating the prey item. Such prey also allow little selection by size because of being cryptic.     

The distribution of Rhododendrin in birch (Betula) species

Rhododendrin (as rhododendrol) was identified in hydrolyzed bark of 14 species of birch. Betula, representing all taxonomic categories in the genus. Only B. lenta and B. nigra of Subsection Costatae lacked this compound.     

Biogeography of Hysterangiales (Phallomycetidae, Basidiomycota)

To understand the biogeography of truffle-like fungi, DNA sequences were analysed from representative taxa of Hysterangiales. Multigene phylogenies and the results of ancestral area reconstructions are consistent with the hypothesis of an Australian, or eastern Gondwanan, origin of Hysterangiales with subsequent range expansions to the Northern Hemisphere. However, neither Northern Hemisphere nor Southern Hemisphere taxa formed a monophyletic group, which is in conflict with a strictly vicariant scenario. Therefore, the occurrence and importance of long-distance dispersal could not be rejected. Although a pre-Gondwanan origin of Hysterangiales remains as a possibility, this hypothesis requires that Hysterangiales exist prior to the origin of the currently recognized ectomycorrhizal plants, as well as the arrival of mycophagous animals in Australia. This also requires that a basal paraphyletic assemblage represents parallel evolution of the ectomycorrhizal symbiosis, or that Hysterangiales was mycorrhizal with members of the extinct flora of Gondwana. Regardless, models for both ancient and more recent origins of Hysterangiales are consistent with truffle-like fungi being capable of transoceanic dispersal.     

A review of the systematics of the sleeper shark genus Somniosus with redescriptions of Somniosus ( Somniosus) antarcticus and Somniosus ( Rhinoscymnus) longus (Squaliformes: Somniosidae)

Past treatments of the sleeper shark genus Somniosus generally recognize three species: S. microcephalus, S. pacificus, and S. rostratus. Based on morphometrics and meristics, we conclude that this genus includes two subgenera (Somniosus and Rhinoscymnus) and five species. Subgenus Somniosus differs from Rhinoscymnus by being much larger when adult and in having more numerous tooth rows in the lower jaw, hooklike rather than leaf-shaped dermal denticles, more numerous spiral valve and vertebral counts, and a poorly calcified vertebral column. Subgenus Somniosus includes S. (Somniosus) microcephalus and S. (S.) pacificus of the Northern Hemisphere and S. (S.) antarcticus of the Southern Hemisphere. Although Somniosus antarcticus has been synonymized with S. microcephalus and identified as S. pacificus in past literature, it differs from S. microcephalus in having a shorter interdorsal space, a more posterior first dorsal fin, lower dorsal fins, more numerous tooth rows in the lower jaw, more numerous spiral valve counts, and fewer precaudal vertebrae. Somniosus antarcticus also differs from S. pacificus by having a shorter prebranchial length, lower dorsal fins, more numerous spiral valve counts, and slightly more precaudal vertebrae. Subgenus Rhinoscymnus includes S. (Rhinoscymnus) rostratus from the eastern North Atlantic and Mediterranean Sea (senior synonym of S. bauchotae) and S. (R.) longus from the western Pacific Ocean. Somniosus longus has been synonymized with S. rostratus, but differs in having a relatively longer second dorsal fin, a slightly larger eye, more lower tooth rows, and slightly higher spiral valve counts. Both Somniosus (Somniosus) antarcticus and S. (Rhinoscymnus) longus from the Pacific Ocean were redescribed. A key to the species and the geographical distribution of all species are provided.     

dnaA suppressor (dasF) mutants of Escherichia coli are stable DNA replication (sdrA/rnh) mutants

Summary The possible allelic relationship between dasF (dnaA suppressor) and sdrA/rnh (stable DNA replication/RNase H) mutations was examined. dasF mutations could not only suppress various dnaA(ts) mutations, but also the insertional inactivation of the dnaA gene or deletion of the oriC sequence, as could sdrA mutations. dasF mutants were found to exhibit the stable DNA replication phenotype, and the sensitivity to rich media, of sdrA mutants. The dasF and sdrA mutations were mapped very closely between metD and proA on the E. coli genetic map. The mutations were recessive to the wild-type allele for all the above phenotypes. It was concluded that dasF is allelic to sdrA/mh.     

Neoechinorhynchus (Neoechinorhynchus) chimalapasensis n. sp. (Acanthocephala: Neoechinorhynchidae) from the freshwater fish Awaous banana (Valenciennes) (Gobiidae) in Mexico

Neoechinorhynchus (Neoechinorhynchus) chimalapasensis n. sp. (Eoacanthocephala: Neoechinorhynchidae) is described from the intestine of Awaous banana (Valenciennes) (Pisces: Gobiidae) collected in the Río Negro, a tributary in the upper Río Coatzacoalcos basin, Santa María Chimalapa, Oaxaca State, Mexico. It is the third species of Neoechinorhynchus Stiles & Hassall, 1905 described from Mexican freshwater fishes, although 36 other species are known from freshwater fishes in the Americas. Like four other species of Neoechinorhynchus from freshwater fishes in North America and Mexico, N. (N.) limi Muzzall & Buckner, 1982, (N.) rutili (Müller, 1780) Stiles & Hassall, 1905, N. (N.) salmonis Ching, 1984 and N. (N.) roseus Salgado-Maldonado, 1978, males and females of the new species are less than 20 mm in length, lack conspicuous sexual dimorphism in size, have a small proboscis of about 0.1 mm in length with the largest hooks being the anteriormost, about 30–90 μm in length and of equal size, and have subequal lemnisci, larger than the proboscis receptacle but still relatively short and, in males, generally restricted to a position considerably anterior to the testes. The new species is closest to N. (N.) roseus, but it is distinguished from it by having: (1) a slightly larger cylindrical proboscis with almost parallel sides versus a globular proboscis with a rounded tip which is shorter and somewhat wider in N. (N.) roseus; (2) smaller but robust anterior proboscis hooks that do not reach the equatorial level or extend beyond the hooks of the middle circle as in N. (N.) roseus; and (3) the female gonopore situated ventrally subterminal, as opposed to being a significant distance anteriorly to the posterior extremity in N. (N.) roseus.     

Ascomycetes on Polytrichadelphus aristatus (Musci)

Fourteen herbarium specimens of Polytrichadelphus aristatus (Polytrichaceae, Musci) from the northern Andes were found to be colonized by ascomycetes. Thirty fungal specimens are indicated representing nine species and six genera. They belong to the first records of bryophilous fungi of northern South America. Five taxa are proposed as new: the genus Aphanotria, and the species A. paradoxa, Bryochiton macrosporus, Bryorella imitans, and Massarina polytrichadelphi. Most frequently found were Rogellia triseptata with six and Bryochiton macrosporus with five records. Four species develop their ascomata between the photosynthetic leaf lamellae, three are immersed within the abaxial side of the leaf nerve and two grow below the adaxial cuticle. The hypocrealean A. paradoxa, which has huge but almost invisible ascomata, merits special attention. Apart from a pronounced rostrum, these are completely immersed within the leaf nerve but longitudinally orientated occupying a type of microniche hitherto unknown. Hyphae of several species attack the thick-walled stereids of the leaf nerve and strongly contribute to leaf decomposition. Polytrichadelphus aristatus has an assemblage of parasitic ascomycetes quite different from that of P. magellanicus from southern South America.     

长白山白桦(Betula platyphlla)纯林和白桦山杨 (Populus davidiana)混交林凋落物的分解

采用交互分解实验,研究长白山白桦叶片和白桦、山杨与水曲柳混合叶片在白桦纯林和白桦山杨混交林内的分解过程。两年的分解实验结果表明,两种类型叶片均存在一个快速分解阶段和一个慢速分解阶段,森林类型和凋落物类型对凋落物分解率的影响在快速分解阶段不显著而在慢速分解阶段显著;混交林内的环境促进了凋落物分解和养分元素释放;在同一林型内,底物质量高的混合叶片其分解率和养分元素释放率均大于底物质量低的白桦叶片;凋落物的底物质量在一定程度上可以抵消森林类型对凋落物分解的影响;白桦山杨混交林混合叶片分解速率和养分元素释放率要显著大于白桦纯林内的白桦叶片,说明白桦山杨混交林的物质循环速度和养分元素供应能力要显著大于白桦纯林。     

Biologie und Verhalten zentralasiatischer Schneefinken (Montifringilla) und Erdsperlinge (Pyrgilauda)

Snow Finches and Mountain-steppe Sparrows differ in habitat selection, feeding, social and vocal behaviour. For these reasons, separation of the genusMontifringilla intoMontifringilla andPyrgilauda is recommended.     

The distribution and abundance of Lernaeocera lusci (Copepoda) on hake (Merluccius merluccius) and bid (Trisopterus luscus) (Teleostei)

Distribution patterns, mean intensity and prevalence of Lernaeocera lusci (Copepoda, Pennellidae) in its 2 hosts Trisopterus luscus (Teleostei, Gadidae) and Merluccius merluccius (Teleostei, Merlucciidae) were examined, together with parasitic abundance and aggregation in relation to the size of the host. The mean parasite abundance and the variance to mean abundance ratio increased with host size, suggesting that the accumulation of this parasite had no noticeable impact on the structure of either host population. Merluccius merluccius being a newly colonized host in the Mediterranean, these results are discussed in relation to current ideas on the evolution of pathogenicity in heterospecific associations.     

Revision of some Thecaphora species (Ustilaginomycotina) on Caryophyllaceae

Specimens of Thecaphora saponariae s. lat. from several caryophyllacean host plants belonging to the genera Cerastium, Dianthus, Petrorhagia, Saponaria, Silene, and Stellaria were studied by means of both LM, SEM, and molecular phylogenetic analyses using ITS and LSU rDNA sequences. The data show that T. saponariae s. lat. is not uniform but represents several taxa. Molecular phylogenetic analyses, correlated with morphology of the sori, spore balls, and spores, permitted the recognition of five species. Two new species, Thecaphora italica and T. cerastii are described, and two new combinations, T. alsinearum and T. melandrii are proposed. The anamorph of Thecaphora saponariae is reported for the first time. A lectotype is designated for Sorosporium silenes-inflatae. Evolutionary aspects are discussed.