A Review of the Biology and Ecology of the Quagga Mussel (Dreissena bugensis), a Second Species of Freshwater Dreissenid Introduced to North America

SYNOPSIS. North America's Great Lakes have recently been invadedby two genetically and morphologically distinct species of Dreissena.The zebra mussel (Dreissena polymorpha) became established inLake St. Clair of the Laurentian Great Lakes in 1986 and spreadthroughout eastern North America. The second dreissenid, termedthe quagga mussel, has been identified as Dreissena bugensisAndrusov, 1897. The quagga occurs in the Dnieper River drainageof Ukraine and now in the lower Great Lakes of North America.In the Dnieper River, populations of D. polymorpha have beenlargely replaced by D. bugensis; anecdotal evidence indicatesthat similar trends may be occurring in the lower LaurentianGreat Lakes. Dreissena bugensis occurs as deep as 130 m in theGreat Lakes, but in Ukraine is known from only 0–28 m.Dreissena bugensis is more abundant than D. polymorpha in deeperwaters in Dneiper River reservoirs. The conclusion that NorthAmerican quagga mussels have a lower thermal maximum than zebramussels is not supported by observations made of populationsin Ukraine. In the Dnieper River drainage, quagga mussels areless tolerant of salinity than zebra mussels, yet both dreissenidshave acclimated to salinities higher than North American populations;eventual colonization into estuarine and coastal areas of NorthAmerica cannot be ignored.     

Modulation of the Host's Immune Response to Plasmodium berghei by a Parasite-Derived Immunosuppressive Factor

ABSTRACT. It is well known that Plasmodium -infected hosts are immunosuppressed, as shown by their depressed immune responsiveness to a variety of antigens. It is not known, however, whether the immune response of malaria-infected animals to the malarial parasite itself is suppressed. The availability of a noninfectious, immunosuppressive factor (ISF) derived from Plasmodium berghei -infected rat erythrocytes made it possible to investigate this question. Mice infected with P. berghei and injected with the ISF had higher levels of parasitemia and shorter survival times than control mice that were similarly infected but were treated with control material derived from noninfected rat erythrocytes or with saline solution. Conversely, mice immunized against the ISF and then infected with P. berghei had lower parasitemias and longer survival times than mice immunized with the control material or with saline solution. We conclude that immunosuppression in murine malaria affects the course of malaria infection.     

The sipunculan genus Lithacrosiphon Shipley. A taxonomic review

A critical review of the sipunculan genus Lithacrosiphon , based on all of the type material and museum specimens with the exception of L. uniscutatus , results in the combining of nine species into three. L. maldivensis with its granular anal shield remains unchanged. L. cristatus with a grooved anal shield and both unidentate and bidentate hooks is redescribed and now includes L. altriconus, L. gurjanovae, L. indicus , and L. odhneri . The L. uniscutatus complex which allegedly has only unidentate hooks is discussed and now includes L. kukenthali and L. poritidis . This is a troublesome species as the pertinent specimens were either unavailable ( L. uniscutatus ) or with missing introverts ( L. kukenthali and L. poritidis ). An identification key is provided and the several morphological characters used for purposes of identification are reviewed and evaluated.     

Reproductive biology of the Pteridophyta IV. An experimental study of mating systems in Ceratopteris thalictroides (L.) Brongán

Gametophytes of the fern Ceratopteris thalictroides originating from four different geographic areas were studied morphologically and genetically. Intraspecific variability was found among the collections for gametophyte morphology and the frequency of lethal sporophytic genotypes. The differences in gametophyte morphology were shown to result in a different mating system for each collection.     

Paradoxes in Western Creativity

Statistical data, showing percentages of creativity in the various arts and philosophy among different nations during the history of Western civilization, can now be presented. This covers the ground quantitatively which Kroeber's Configurations of Culture Growth covered qualitatively. The study not only reveals different patterns among nations, but indicates the nature of the problem to be overcome if mankind is to achieve a universal maximum release of creativity for all in the future.     

Double Stranded RNA from Rat Liver induces Interferon in Rat Cells

Double stranded RNA from rat liver induces interferon in rat ergbryo fibroblasts. This shows that the production of interferon is not only a reaction to “foreign” RNA but can also be obtained with RNA of the same species.     

Purification and Properties of Purified Hexokinase from the African Trypanosomes and Trypanosoma equiperdum

SYNOPSIS. Hexokinase was in both soluble and particulate fractions of extracts of Trypanosoma brucei, T. gambiense, T. rhodesiense and T. equiperdum. These enzymes have been purified some 350-fold from crude extracts by sonication, (NH₄)₂SO₄ fractionation, and DEAE Sephadex column chromatography. Purified hexokinases had: A) temperature optimum 45-50 C; B) pH optimum 6.5-7.0; C) Mg⁺⁺ and ATP requirements; D) inhibition by ADP, p -hydroxymercuribenzoate, glucose-6-phosphate, and competitive inhibition by mannose, glucosamine, N -acetyl-D-glucosamine and xylose; E) ability to phosphorylate glucose, fructose, mannose, 2-deoxy-D-glucose and glucosamine; F) a glucose requirement for stabilization. T. equiperdum hexokinase was inhibited 33% by ADP as compared to 17-20% with brucei group hexokinase, and showed 22% activity when ITP was substituted for ATP in contrast to 35-40% with brucei group hexokinase.     

Glutamine synthesis in germinating seeds of Cucurbita moschata

During germination, an increase in glutamine and glutamine synthetase[L-glutamate: ammonia ligase (ADP), EC 6.3.1.2 [EC] ] occurred inthe cotyledons reaching a maximum at 4 to 6 days. The enzymehad a Km of 4.5 nun for L-glutamate, and 0.67 mu for hydroxylamine.Hydroxylamine exhibited substrate inhibition kinetics. The enzymewas inhibited by calcium ion, fluoride ion and p-hydroxymercuribenzoatebut not by EDTA, sodium ion or chloride ion. The sulf hydrylinhibition was reversed by dithiothreitol. In vivo synthesisof glutamine-¹⁴C from glutamate-¹⁴C was found to parallel theincrease in glutamine content and the in vitro glutamine synthetaseactivity during germination. ¹ Present address: Department of Biology, Mercyhurst College,Erie, Pennsylvania 16501, U.S.A. (Received June 12, 1971; )     

Temperature Response Pattern during Afterripening of Achenes of the Winter Annual Krigia oppositifolia (Asteraceae)

Abstract Freshly-matured achenes of Krigia oppositifolia Raf. were buried in soil at near-natural temperatures for 0–35 months and then exhumed and tested in light and darkness at (12/12 hr) daily thermoperiods of 15/6, 20/10, 25/15, 30/15 and 35/20°C. Achenes required light for germination and exhibited an annual dormancy/nondormancy cycle, being dormant in spring and nondormant in autumn. High summer temperatures (30/15, 35/20°C) fully promoted afterripening, whereas low temperatures (5, 15/6°C) prevented it. As buried seeds came out of dormancy in summer, they first germinated at medium temperatures (20/10, 25/15°C), but with additional afterripening the maximum and minimum temperatures for germination increased and decreased, respectively. Thus, during afterripening, achenes exhibit type 3 temperature responses, which otherwise are known only in two perennial Asteraceae and one perennial Liliaceae. The physiological responses of achenes of K. oppositifolia are unlike those of most winter annuals, which have type 1 responses—i.e., the maximum temperature for germination increases during afterripening. Also, they are unlike the majority of Asteraceae, which have type 2 responses—i.e., the minimum temperature for germination decreases during afterripening. Type 1 responses, typical of most winter annuals, have yet to be reported in the Asteraceae.     

Plant water deficits and insect responses: the preference of Corythucha arcuata (Heteroptera: Tingidae) for the foliage of white oak, Quercus alba

ABSTRACT.

• 1 The preference of Corythucha arcuata (Say) (Heteroptera: Tingidae) for the foliage of Quercus alba L. (Fagaceae) grown under water deficit was examined. Potted Q.alba saplings were grown under controlled levels of water deficit in a glasshouse. Adult C.arcuata were exposed to excised Q.alba foliage under controlled conditions in a growth chamber, and feeding preference assessed by recording the percentage of individuals feeding on leaves from each level of water deficit.
• 2 Two experiments were performed. In the first, all foliage was supplemented with water (via the petiole) to alleviate physical changes in the leaves that accompany plant water deficits. In the second experiment, leaves were not supplemented with water.
• 3 C.arcuata had no preference when presented water supplemented leaves, but preferred leaves that were fully hydrated when presented leaves that were not supplemented with water.
• 4 These results suggest that plant water deficits are important in determining the feeding preference of C.arcuata because they lead to avoidance of drought grown foliage. This avoidance may be caused by an increase in the metabolic cost to the herbivore of maintaining water balance when ingesting drought grown foliage or to an increase in foliage toughness.