The Melampyrum sylvaticum group is a complex of three closely related species. This group is most variable in the Carpathian region. Interactions among different levels (within-population to interspecific) of genetic variation and influence of the environment are considered to be the main sources of the complicated morphological variation in this region. Morphological variation in the M. sylvaticum group was studied in mountain ranges of the Hercynian Massif and in the Western and Ukrainian Carpathians. Several populations were sampled at different altitudes within each mountain range. Hierarchical partitioning of morphological variation at different levels (within populations, among populations within a mountain range and among mountain ranges) was calculated. Correlations among groups of morphological characters and altitude were calculated. The largest proportion of variation on a large geographic scale (i.e. among mountain ranges) was detected in anther length and several corolla characters (length of the lower corolla lip, height of upper corolla lip), whereas these traits were homogeneous at a local scale (within populations and among populations in one mountain range). An opposite pattern (i. e. high proportion of variation at the low levels, which blurred possible large scale differences) was found in bract traits and several calyx characters. Moreover, a strong correlation between bract length and altitude was observed. The observed changes in the proportions of morphological variation and response to altitude suggest a close connection between bract characters and environmental factors (or lower levels of genetic variation). On the other hand, some of the flower characters seem to be genetically determined and thus might reflect evolutionary processes (early diversification, potential hybridization, introgression) on which the taxonomic treatment of the group should be based. The most distinct differences were detected between samples from the Ukraine and south-western part of Bohemia. Populations from the the Sudeten Mts and the Western Carpathians were variable and morphologically intermediate, forming a continuum between the two extremes.
Seven species of fishes, Catostomus commersonii (Lacépède), Etheostoma nigrum Rafinesque, Micropterus dolomieu Lacépède, Notemigonus crysoleucas (Mitchill), Notropis hudsonius (Clinton), Perca flavescens (Mitchill), and Percina caprodes (Rafinesque) from the St. Lawrence River, Quebec, Canada, were found infected with progenetic specimens of Neochasmus spp. in the orbits and/or the body musculature. Worms displayed varying degrees of maturation. Eggs occupied the entirety of the worm in late stages of development and persisted as distinct clusters in situ after worm death. Populations of parasites were studied monthly in E. nigrum from one site between May and October in order to follow parasite recruitment, development and maturation. Recruitment of parasites was observed in young-of-the-year fish primarily in July and continued through October. Worms matured rapidly, displaying egg production within a month. Later developmental stages, in which eggs occupied most of the worm, and clusters of eggs became abundant by September. Infections in overwintered fish collected in May consisted mainly of worms in early stages of egg production and of clusters of eggs. When hatched artificially, eggs from the clusters released viable miracidia, indicating that they survive beyond the lifespan of the adult worm. It is suggested that progenesis is a fixed characteristic of the life cycle of these species, that egg dispersal requires the death of the host and that it is facilitated by predation. All prior records of Neochasmus spp. are examined, leading us to conclude that the role of the putative definitive host (primarily basses) has been reduced to that of a dispersal agent. Current hypotheses concerning the evolution and maintenance of progenesis are considered, but it is concluded that they do not apply to this host-parasite system.
The riparian forests along the Tarim River, habitats for Populus euphratica establishment, are subjected to frequent flooding. To elucidate adaptive strategies that enable this species to occupy the riparian ecosystem subjected to seasonal or permanent water-logging, we examined functional characteristics of plant growth, xylem water relations, leaf gas exchange, chlorophyll (Chl) content and fluorescence, soluble sugar and malondialdehyde (MDA) content in P. euphratica seedlings flooded for 50 d. Although flooded seedlings kept absorbing carbon throughout the experiment, their shoot and root growth rates were lower than in non-flooded seedlings. The reduced leaf gas exchange and quantum efficiency of PSII of flooded seedlings resulted possibly from the reduction in total Chl content. Content of soluble sugar and malondialdehyde in leaves were higher in flooded than in control seedlings. Soil flooding induced hypertrophy of lenticels and increased a stem diameter. These responses were responsible for species survival as well as its success in this seasonally flooded riparian zone. Our results indicate that P. euphratica is relatively flood-tolerant due to a combination of morphological, physiological, and biochemical adjustments, which may support its dominance in the Tarim riparian forest., B. Yu, C. Y. Zhao, J. Li, J. Y. Li, G. Peng., and Obsahuje bibliografii
The fish leech Johanssonia arctica (Johansson, 1898) was collected from king crabs Paralithodes camtschaticus (Tilesius, 1815) in Finnmark, N Norway, and allowed to feed on experimental fish hosts in the laboratory. This leech ingested blood from laboratory-reared cod (Gadus morhua) and halibut (Hippoglossus hippoglossus). Some experimental halibut acquired trypanosome infection, with parasitaemia between ca. 500 and 60,000 trypanosomes ml-1. The trypanosomes were of variable size and measured 39-90 µm (mean 57 µm) ca. 81 days post-infection. Characteristic features are cell striation, refractile cytoplasmic granules, anterior nucleus and a relatively long (ca. 6 µm, max 9 µm) distance from the posterior end to the kinetoplast. Following growth, the trypanosomes became increasingly slender, with fewer striae and a nucleus position less pronounced anterior. The trypanosome is considered distinct from a type transmitted by the leech Calliobdella nodulifera (Malm, 1863) in the NE Atlantic, but is regarded conspecific with a trypanosome transmitted by J. arctica in the NW Atlantic. This trypanosome has in the past been identified as Trypanosoma murmanensis Nikitin, 1927, a poorly described species. T. murmanensis cannot be recognized with certainty among the trypanosomes transmitted by C. nodulifera and J. arctica respectively. We propose that the J. arctica-transmitted species is considered T. murmanensis Nikitin, 1927 sensu stricto.
Quasi Stationary Spiral Structure is the natural Interpretation for grand deqlgn spiral galaxies. The best theoretical tool to descrlbe QSSS morphologles is the study of spiral modes. Modal studies are characterlzed by two distinct stages. At the dynamical level, one wishes to compute spiral modes efflcently on a variety of equilibrium models and to master the relation between the properties of the basic states and the propertles of the relevant spiral modes. At the astrophysical level, realistic basic states are identified by dlscussing the processes of evolutlon and
self-regulatlon; in partlcular, we Identify some basic states conslstent wlth QSSS grand designs and others where more flocculent spiral structure is expected to occur. For thls second stage It is cruclal to have a proper interpretation of the results obtained from one-component models In vlew of the multiple component astrophysical systems to be described (which include stars, Population 1 objects, and cold gas). Followlng this outllne, under the guidance of a slmple analytlc (asymptotic) theory, a very large set of galaxy models has been studled numerically. Thls is essentlally a three dimensional survey wlthln a flexlble class of models, where one parameter measures the amount of partlclpatlng disk mass, a second parameter determlnes the
hotness of the disk and the third is a scale length which combines propertles of the slze of the nuclear bulge and the dlstrlbutlon of the cold gas component. All the essentlal morphologlcal types found in the Hubble diagram have been reproduced; in partlcular, parameter reglmes are identified for SA and SB galaxies and speclfically for SBO, SB-r and SB-s objects. Dlstinction is made between systems where gas is expected to play an actlve or a passlve role.
The epidermis of the Korean spined loach Iksookimia koreensis was divided into three layers: an outermost layer, middle layer and stratum germinativum. And the dermis was composed of two layers: stratum laxum and compactum. The outermost layer consisted of polygonal cells or flattened cells, small amount mucous cells, and the middle layer consisted of two types of skin glands, a small mucous cell and a large club cell. The mucous cell was acid sulfomucins (some sialomucins), but the club cell did not show any histochemical reaction to mucosubstances. The stratum germinativum was composed of a cuboidal epithelial cell and a well-defined lymphatic space containing small lymphocytes. There was a large number of blood vessels just below the basement membrane. The stratum laxum of dermis has small scales and a definite area that was AB positive and PAS positive.
We compared cranial, dental, bacular and chromosomal variables between a population of Graphiurus murinus collected in riverine forest in the Andries Vosloo Kudu Reserve (AVKR) near Grahamstown (N= 32), and another from Afromontane forest at Hobbiton on Hogsback (HH), in the Amathole Mountains (N=21), Eastern Cape, South Africa. AVKR dormice were significantly larger in 13 out of a total of 23 cranial dimensions and they had a relatively longer rostrum. The 4th upper premolar was clearly longer and the tip of the baculum broader in the sample from HH. Discriminant function analyses of cranial and dental parameters perfectly separated the two samples. The karyotypes were the same at both localities (2n= 46; NFa = 92) but differed from previously reported karyotypes of Graphiurus species from Africa.
The morphology of two Salvelinema Trofimenko, 1962 species, S. salmonicola (Ishii, 1916) and S. walkeri (F.kbaum, 1935), swimbladder nematodes of salmonids, was studied in detail, including scanning electron microscopy (SEM), on the basis of newly collected materials from Oncorhynchus masou, О. mykiss and Salvelinus malma from Japan and from Oncorhynchus ciarki, О. kisulch and O. nerka from North America (Vancouver Island, B.C., Canada and Gulf of Alaska). Both nematode species proved to be morphologically very similar, differing substantially in the numbers and arrangements of egg filaments. Deirids were described for the first time for Salvelinema. Salvelinema iwana (Fujita, 1928), S. amemasu (Fujita, 1939), S. kosugii (Fujita, 1939), S. oncorhynchi (Fujita, 1939) and S. salvelini (Fujita, 1939) (= S. ishii (Fujita, 1941)) were synonymised with S. salmonicola. Comephoronema Layman, 1933 is re-erected as a valid genus related to Salvelinema.
Two Stomylotrema Looss, 1900 species were found in storks and grebes in Cuba. Five specimens of Stomylotrema bijugum Braun, 1901 were recovered from the roseate spoonbill, Ajaia ajaja (Allen, 1942) (Ciconiiformes) while six Stomylotrema vicarium Braun, 1901 were found in the little blue heron, Egretta (syn. Florida) caerulea (L.) (Ciconiiformes) and the least grebe Podiceps dominicus dominicus (I,.) (Podicipediformes). The taxa represent new host and geographical records. The problem of morphological variation within the genus Stomylotrema is briefly analysed in the discussion.