Alchemilla austriaca,spec. nova,(Rosaceae) — eine neue Art aus den Ostalpen

Alchemilla austriaca is a new species which belongs to the group ofA. demissa, A. frigens, A. longana, A. longiuscula, A. semisecta, andA. sinuata. The holotype specimen as well as leaf and flower details are illustrated (Figs. 1–3). A complete character analysis is given, differences and similarities of allied species are presented in two tables, and the position of the group within the genus is discussed.A. austriaca so far is known only from the Austrian Alps and mainly from the central ranges (distribution map: Fig. 4). Its wet subalpine and alpine habitats are characterized by species lists.

     

Responsiveness of the lamb ductus arteriosus to prostaglandins and their metabolites

The relative potencies of the prostaglandins A₁, A₂, E₁, E₂, F_2α and their 15-keto-, 15-keto-13,14-dihydro-, and 13,14-dihydro-metabolites were investigated on isolated lamb ductus arteriosus preparations contracted by exposure to elevated PO₂. All the prostaglandins (except PGF_2α and its 15-keto-metabolites) relaxed the tissue. However, only PGE₁, E₂, and their 13,14-dihydro-metabolites, were effective at concentrations below 10⁻⁸ M. Therefore, events that alter metabolism of circulating PGs in the perinatal period may have significant effects on the relative patency or closure of the ductus arteriosus.     

Light and Electron Microscopic Observations of Gametogenesis in Hastigerina pelagica (Foraminifera)*

SYNOPSIS. During gametogenesis mother individuals of Hastigerina pelagica (d'Orbigny) undergo significant morphological changes. Thirty h before gamete release, the cytoplasm changes from pale orange to bright red, possibly due to transport of stored lipids from the inner region to more peripheral parts of the cytoplasm. During the next 10 to 15 h the bubble capsule which surounds the calcareous shell is discarded. After all bubbles have disappeared, the individual sheds its spines by resorbing the spine bases close to the shell surface. A single mother nucleus divides into some hundreds of thousands of gamete nuclei within a span of ～ 20 h. A bulge of cytoplasm is extruded from the aperture and increases in size during the next 5 to 10 h. This bulge consists of cytoplasmic strands in which gametes and spherical bodies are embedded. The gametes and spherical bodies mature and are released during the afternoon and early evening. The gametes have 2 unequal acronematic flagella. A previously undescribed structure in foraminiferal reproduction is the spherical body which consists of a large vacuole surrounded by a thin cytoplasmic layer in which several nuclei, various typical cell organelles and multiple flagella are present. The spherical bodies are believed to play a role as receptacles of waste material, possibly including residual digestive enzymes, thereby protecting the gametes from lysis during the reproductive process. Fusion of gametes and further development into the next generation have not been observed.     

Differentiation of Gametocytes in Microcultures of Human Blood Infected with Plasmodium falciparum*

SYNOPSIS. Gametocytes differentiated from ring-stage parasites in microcultures of human blood infected with Plasmodium falciparum. Immature gametocytes could be distinguished morphologically from late asexual trophozoites after ～ 40 h of culture. Differentiation into crescentic forms took several days and the incorporation of [³H]-isoleucine by developing gametocytes was demonstrated. About 1% of red cells contained gametocytes at the maximum densities attained. Differentiation of gametocytes occurred either directly from rings placed in culture or from the progeny of subsequent cycles of schizogony and invasion in vitro. The latter occurrence was confirmed by the development of gametocytes in marker fetal red cells added to cultures, although fetal red cells provide a less favorable environment than those with HbA for growth of the parasites.     

Species turnover in deciduous forest vegetation

Summary Permanent quadrats were marked out in two areas of hardwood forest vegetation in 1969, and listings of their vascular plant species were taken on several occasions over the snow-free seasons of 1969, 1970, 1971 and 1976. Over the period of study, mean numbers of species per m² remained virtually constant, but variations in the species compositions of individual quadrats were such that mean turnover ratios of 0.115 and 0.085, respectively, were computed for the two stands. Between 1969 and 1976 averages of 20% and 14%, respectively, of the species found in individual quadrats were replaced. This was not accomplished by qualitative changes in the floras of the two stands. Rather, it reflects the operation of a system of continuous rearrangements of species in the small quadrats of both sample areas.Taxonomical nomenclature and life-form system used in this study are according to Gleason & Cronquist (1963).William Phillips, Ian Sutherland and Sheila Thompson helped in the field; Professor Keith Wade commented on the material; Abal Sen drafted the diagram; and the research is part of that funded by the National Research Council of Canada.     

Relation Between Cell Union and Nuclear Reorganization in Triplet Conjugants of Paramecium caudatum and Paramecium multimicronucleatum

SYNOPSIS Triplet conjugants of Paramecium caudatum which appeared naturally in mating mixtures and those of Paramecium multimicronucleatum which were produced by conjugation-inducing chemicals were isolated. Triplet conjugants lasting for more than 3 h were stained to examine macronuclear events. In P. caudatum , only 2 triplets among 182 (1%) contained macronuclear fragmentation in all 3 members. The most frequently occurring triplets (79%) were those producing 1 cell without and 2 cells with macronuclear fragments. There were also triplets (17%) producing 1 cell with, and 2 without macronuclear fragments, and some (3%) with 3 cells that contained no fragments. The length of persistence of the triplet was not responsible for the occurrence of macronuclear fragmentation in the 3rd cell of the triplet. In P. multimicronucleatum , the same 4 classes of triplets occurred, but the most frequently occurring class was that consisting of 3 cells (91%) with macronuclear fragments. Induction of nearly 100% of triplets with 3 such cells was possible by isolating the triplets' from a culture which was treated chemically at about 24 h after the last feeding. Treatment with chemicals in starved cultures resulted in triplets with incompletely fragmented or nonfragmented macronuclei. Further, in P. multimicronucleatum , chemicallyinduced triplets involving only holdfast pairs to which the 3rd cells were uniting often produced 3 cells with fragmented macronuclei.     

Behavior of a Virus in a Symbiotic System, Paramecium bursaria—Zoochlorella

SYNOPSIS In a culture system of Paramecium bursaria , virus particles were found in large number. The particle was able to infect and multiply in certain cells of the zoochlorella, an intracellular symbiotic alga of P. bursaria. The infective particle, designated as zoochlorella cell virus (ZCV), was icosahedral and 120–180 nm in edge to edge diameter. The ZCV particle was found to differ from any of the already established viruses attacking the green and the blue-green algae. Within the system where P. bursaria cells were growing, ZCV particles were detected in the depression of the pellicle, among the cilia growing in the cytopharynx, and in the food vacuole of P. bursaria. ZCV particles were infective only for the zoochlorella cells which were recently released from the cytoplasm of P. bursaria. The multiplication process of ZCV comprised the adsorption of the particle to the cell wall of the zoochlorella, the penetration of nucleic acid into the host cell interior, the replication of viral constituents, the maturation of viral particles and their final release by the burst of the zoochlorella cell. ZCV particles appeared only in the cytoplasmic region of the zoochlorella cell in which many ribosomes were distributed. A possible ecosystem among the 3 members consisting of P. bursaria , zoochlorella and ZCV is discussed.