The diet of the King Penguin Aptenodytes patagonicus at Macquarie Island

The diet of King Penguins Aptenodytes patagonicus at Macquarie Island was studied between November 1984 and November 1985 based on stomach flushed samples (obtaining 93% of the total stomach content) from ten birds each month. The mean stomach content mass of the 118 samples was 923 0 g. Percentage by number, percentage by weight and dietary coefficient analysis all showed the main prey of the penguins to be myctophid lantern fish of the species Electrona carlsbergi and Krefftichthys anderssoni. Juvenile fish of both species were eaten from December to July, and adults in August and September. Cephalopods were relatively unimportant in contrast to previous indications. The amount of food brought ashore and the composition of the diet varied over the year, with K. anderssoni the dominant food in all but the winter months when E. carlsbergi replaced it as the principal food item.     

Antigenic Relationship Between Plasmodium falciparum and Babesia bovis: Reactivity with Antibodies to Culture-Derived Soluble Exoantigens1

Antigenic similarities between Plasmodium and Babesia parasites of the phylum Apicomplexa have been previously demonstrated primarily by the serological cross reactivity observed in the indirect fluorescent antibody (IFA) test. We have now studied the antigenic relationship between the human malaria parasite, Plasmodium falciparum, and the hemoparasitic agent of cattle, Babesia bovis, using rabbit monospecific antibodies produced against individual culture-derived P. falciparum polypeptides and bovine polyspecific antibodies to B. bovis exoantigens. These respective antibodies were found to be distinctly cross reactive in the IFA test using infected erythrocytes (squirrel monkey—P. falciparum; bovine—B. bovis) as antigen substrates. Immunofluorescence was shown to be highly specific for parasite surfaces. Additionally, the degree of reactivity with soluble exoantigens contained in Plasmodium and Babesia culture supernatants was monitored by a two-site enzyme immunoassay employing the cross-reactive antibodies. Further evidence for antigenic cross reactivity between P. falciparum and B. bovis parasites was shown with the in vitro inhibition assay. Antibodies to P. falciparum and B. bovis were found to be highly inhibitory for the in vitro growth of P. falciparum in human erythrocytes.     

The Gomphaeschninae (Odonata: Aeshnidae): new fossil genus, reconstructed phylogeny, and geographical history

ABSTRACT. Three new species of fossil Anisoptera (dragonflies) are reported from Tiffanian (Late Palaeocene) sediments of the Paskapoo Formation, near Red Deer, Alberta, Canada. The three species are all assigned to the new genus Alloaeschna , which is classified in the subfamily Gomphaeschninae.
Phylogenetic analysis of gomphaeschnine wing venation suggests that the subfamily is paraphyletic, with derived gomphaeschnines such as Boyeria and Linaeschna more closely related to the Brachytroninae and Aeshninae than are other gomphaeschnines. One of the most primitive gomphaeschnines, and the oldest fossil form, is the Jurassic Morbaeschna. Parallelism, convergence and reversal in the evolution of features of the wing venation is common.
The new genus Alloaeschna is at about the same evolutionary grade as the old-world genus Oligoaeschna and the new-world genus Gomphaeschna , and is one of the more primitive known members of the Gomphaeschninae. The new species are the first recorded Palaeocene gomphaeschnines and the oldest known gomphaeschnines from the Americas.
Several extant genera have fossil representatives on continents different from those on which they now survive, suggesting repeated crossing of land bridges and/or widespread ancestral species prior to the separation of the continents, and subsequent extinction leading to present relict distributions.     

The Initiation and Growth of Narcissus Bulbs

Plants of two Narcissus cultivars were dissected periodicallyover a year to study initiation, growth, and dry-weight changesof flowers and daughter bulb units in relation to the positionof the daughter bulbs in the branching system. A Narcissus bulbis a branching system comprising terminal and lateral bulb units;the former bear both terminal and lateral bulb units, but lateralscontain only terminal ones. This basic pattern may be modifiedby the failure of lateral bulb units or the development of supernumeraryones. Differences in bulb unit size, in scale and leaf number,and in flowering, related to position in the branching system,are probably due to the initiation of lateral bulb units somemonths after terminal ones. This affects the growth and behaviourof the laterals and daughter bulb units borne by these lateralsin the next generation. Bulb units live about four years; after the loss of their leafblades and flowers, the scales and leaf bases act as storageorgans whose weight increases or decreases according to thecarbohydrate status of the plant. Growth of bulb units showsan externally controlled alternation of rapid and slow growth.This is likely to be an effect of day length on bulbing.     

Ferri- and Ferrocyanide Salts Change the Current/Voltage Relations of Chara corallina: No Correlation with the Transmembrane Redox System

The current/voltage {I/V) relations of the plasma membrane ofChara corallina cells are characteristic when the bathing mediumhas elevated (5-0 mM) concentrations of potassium Addition ofeither 0-5 mM femcyanide or 0-5 mM ferrocyanide usually induceda qualitatively similar increase in the ‘leak’ current,with a concomitant increase in membrane conductance. Both redoxreactants failed for unknown reasons to affect the I/V profileof some of the cells tested In the sensitive cells, femcyanidewas unable to generate extra current over that found upon additionof ferrocyanide Because the feiTocyanide oxidation rate of thecells is only 10% of the femcyanide reduction rate, we concludethat both forms, fern- and ferrocyanide, affect the 'leak' conductanceindependent of the redox state of the reactants, i e ferrocyanidedoes not act indirectly via an oxidation to femcyanide Hence,under the experimental conditions, we were unable to detecta current that could be assigned to the operation of a transmembraneredox system Furthermore, the fern- and ferrocyanide inducedshift in the I/V profile only reversed slowly after withdrawalof the redox reactants. This suggests that the elicited currentis independent of the presence of an extracellular electronacceptor, i.e on the continuous operation of a proposed transmembraneredox system Key words: Current/voltage curves, transmembrane reductase, voltage clamp, femcyanide, ferrocyanide, Chara     

The impact of the crayfish Orconectes virilis on aquatic macrophytes

SUMMARY. 1. The impact of crayfish on the biomass, density and shoot morphology of four submersed plant species was examined under semi-natural conditions. Male or female crayfish ( Orconectes virilis ) were held for 5 weeks at biomasses of 0, 5, 10 or 18 g m⁻² (live weight) in twelve plastic pools (4.67 m², surface area) containing Potamogeton richardsonii, Myriophyllum exalbescens, Nuphar variegatum and Sparganium eurycarpum .
2. Crayfish significantly affected biomass, density and/or shoot morphology of all four macrophyte species. Differences in the effect of crayfish on macrophyte growth were related to plant species, crayfish sex and activity, and the abundance of alternative foods.
3. The effect of female crayfish on macrophyte growth was generally stimulatory. Myriophyllum and Potamogeton biomass, Potamogeton density and Myriophyllum length increased in the presence of female crayfish, possibly due to the reduction in herbivorous snails as a result of crayfish predation. In contrast, plant growth decreased in the presence of male crayfish: Myriophyllum, Nuphar and Potamogeton biomass, Myriophyllum and Sparganium density, and Sparganium and Poiamogeton length were reduced at male crayfish biomasses between 5 and 18 g m⁻².
4. These results indicate that even relatively low densities of crayfish can greatly affect the growth of submersed aquatic plants. Because of their ability to modify aquatic macrophyte, macroinvertebrate and, ultimately, fish communities, the introduction of crayfish into lakes where they do not occur could have a major effect on the structure and composition of the littoral zone.     

Indirect effects of fish predation on calcite supersaturation, precipitation and turbidity in a shallow prairie lake

SUMMARY.

• 1 We tracked calcite saturation and seston composition during 1987 and 1988 in a shallow, hardwater prairie lake, 1 year before and 1 year after a lake-wide fish removal. We also measured the contribution of calcite to turbidity during 1988.
• 2 In both years calcite saturation increased rapidly after all ice had thawed and peaked during mid-late summer with the mineral saturation index of calcite (SI) sometimes exceeding 30.
• 3 Removal of calcite from lake seston by gentle acidification of unfiltered water samples showed suspended calcite to be an important source of lurbidity in this lake.
• 4 The lake-wide fish removal produced detectable changes in the annual cycle of calcite saturation and precipitation. Increased grazing by Daphnia galeata and Daphnia pulex apparently reduced calcite saturation during early summer by suppressing the phytoplankton, and lowering the demand for CO₂.
• 5 Lower calcite precipitation, as well as direct removal of calcite by Daphnia grazing, probably contributed to the improvement in water transparency observed after the fish kill.