Diets of syntopic finescale dace,Phoxinus neogaeus,and northern redbelly dace,Phoxinus eos: a reflection of trophic morphology

Synopsis We examined relative abundance, distribution, and gut contents of Phoxinus eos and P. neogaeus in a small northern Michigan bog lake. P. eos were usually 5–100 x more abundant than P. neogaeus, but both species were more abundant near the lake margin than offshore. Both species fed primarily on algae and invertebrates associated with the bog mat, but differences in diet were associated with differences in trophic morphology. As expected, because of its relatively longer intestine and smaller mouth, P. eos consumed relatively more plant matter, especially green algae, and fewer macroinvertebrates than P. neogaeus. These dietary conclusions were supported by analysis of two independent data sets. Further work is needed to discriminate between the effects of body size and trophic morphology on diet.     

The release of sterile males into natural populations of the German cockroach Blattella Germanica

A pilot experiment in genetic control of the German cockroach was conducted aboard a small vessel based at Norfolk, Virginia. It utilized sterile (double translocation heterozygotes) whose sterility effects were due to embryonic lethality plus complete entrapment of any remaining viable embryos within the egg case. Initial infestations were reduced by insecticides prior to male release. Three releases of unmated were made at monthly intervals. Infested harborages, located in the course of insecticide application, were used as release sites. The experiment was terminated after 41/2 months. The results showed that released joined groups near release sites and that they competed well against wild type . Apparently neither they nor with which they mated moved far from these sites. Sterility effects differed in respect to specific sites and general areas. Population growth was retarded markedly in the galley, the area of heaviest initial infestation. Terminal infestation was heaviest in the mess deck, although the highest sterility among occurred at/near the mess-deck release site (only one mess deck-infested site was found prior to initation of the experiment). It is suggested that a slight increase in the number released would have suppressed/eliminated groups inhabiting galley harborages, but that site selection was the major problem in the mess deck. Analyses of nymphal age classes and mating types among led to a hypothesis that insecticide-induced dispersal of nymphs resulted in the infestation of many new mess-deck harborages. Population growth was unchecked at these sites because they were too far removed from the sterile male release sites.

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Résumé Une expérience pilote dans la lutte génétique contre Blattella germanica L. a été réalisée sur un petit navire encré à Norfolk, Virginie. La léthalité embryonnaire des mâles stériles utilisés (hétérozygotes à double translocation) était associée au piégeage des quelques embryons viables dans les oothèques. Les pullulations initiales avaient été réduites par des insecticides avant le lâcher des mâles. Des mâles vierges ont été lâchés à trois reprises à un mois d'intervalle. Les abris contaminés, localisés au cours des traitements insecticides, ont été utilisés comme lieux de lâcher. L'expérience s'est achevée au bout de quatre mois et demi. Les résultats montrent que les mâles introduits rejoignent les autres blattes près des lieux de libération et qu'ils ne sont pas défavorisés dans leur compétition avec les autres mâles. Ni eux, ni les femelles avec lesquelles ils se sont accouplés, ne s'éloignent apparemment de ces emplacements. Les effets de stérilisation varient en fonction des sites spécifiques et des zones plus vastes. La croissance de la population est significativement retardée dans la cuisine, zone où l'infestation initiale était la plus élevée. L'infestation finale la plus importante est dans le pont du mess, bien que la stérilité des femelles la plus élevée s'observe à (ou près) du lieu de libération au pont du mess (seulement un lieu d'infestation avait été observé sur le pont du mess avant le début de l'expérience). On pense qu'une légère augmentation de l'effectif libéré aurait supprimé (ou éliminé) les groupes occupant des abris dans la cuisine, mais que la sélection des sites était le principal problème pour le pont du mess. L'analyse des classes d'âges des larves et des catégories de femelles accouplées laisse supposer que la dispersion des larves provoquée par l'insecticide a entrainé la contamination de beaucoup de nouveaux abris dans le pont du mess. La croissance de la population n'a pas été contenue dans ces sites parce qu'ils étaient trop éloignés des lieux de lâcher des mâles stériles.

     

Two new reciprocal translocations in the German cockroach. Cytology and genetics of T(3;12) and T(7;12).

Two new reciprocal translocations in the German cockroach have been analyzed. They were identified cytologically to be T(3;12) and T(7;12). Linkage studies showed that groups XI, IX, and IV are on chromosomes 12, 3, and 7, respectively, and clearly demonstrated sex differences in recombination. Each of these chromosomes have distinctive morphological features that facilitate their identification, and permit breakpoint and centromere localization. A sex difference in fecundity is associated with T(7;12), but not T(3;12). About 40 percent mortality occurred when T(3;12) males or females and T(7;12) females were outcrossed. Outcrossing T(7;12) males produced the expected 50 percent mortality. Cell counts at metaphase I revealed that T(3;12) males exhibit directed segregation, while T(7;12) males do not. Tests for homozygosity indicated that the T(7;12) homozygote is viable. A map of chromosome 12 is presented showing the tentative placement of linkage group XI with respect to interchange breakpoints and chromosome morphology. The results are discussed in relation to possible sex differences in chiasma localization.     

Immunological aspects of benign melanocytic tumours and melanoma in situ

Summary Extracts were prepared from 15 malignant melanomas, 10 naevi, 8 pieces of skin containing atypical melanocytes and 4 samples of normal skin. Peripheral blood leucocytes from 52 patients with benign naevi that had altered sufficiently to cause the patient to seek attention, 57 patients with malignant melanomas, and 98 normal individuals were tested against these extracts in a capillary leucocyte migration test. Melanoma extracts preferentially inhibited the leucocytes of melanoma patients and to a lesser extent those of naevus patients. Melanoma patients' leucocytes were more frequently inhibited by naevus extracts (whether from intradermal or from compound naevi) than were the leucocytes of naevus patients and control donors. Extracts of skin containing atypical melanocytes (perimelanomatous skin and lentigenous skin) selectively inhibited melanoma patients' leucocytes.     

The identification of messenger RNA coding for immunoglobulin heavy and light chains of Xenopus laevis

Total poly(A)-containing mRNA isolated from Xenopus spleens was translated in a rabbit reticulocyte lysate in vitro protein-synthesizing system. Approx. 1% of the radioactivity incorporated into the protein was precipitated by an antibody directed against adult Xenopus IgM. The immunoprecipitated proteins were characterized as IgM heavy and light chains by their molecular weight as determined by polyacrylamide-sodium dodecyl sulfate gel electrophoresis The sequence variability of the synthesized light c hain proteins was analyzed by isoelectric focusing and shown to be indistinguishable from authentic Xenopus immunoglobulin light chain proteins derived from IgM. The data presented here identify Xenopus spleen mRNA as a potential source of a natural immunoglobulin mRNA population with which the development of the immune system can be studied.     

EVOLUTIONARY INFERENCES FROM A COMPARISON OF COCKROACH NUCLEAR DNA AND DNA FROM THEIR FAT-BODY AND EGG ENDOSYMBIONTS

DNA was isolated from muscle tissue and from concentrations of the egg and fat-body endosymbionts of the cockroaches Periplaneta americana, Blatta orientalis, Blaberus giganteus, Gromphadorhina portentosa, Leucophaea maderae, Cryptocercus punctulatus, and Nyctibora lutzi. Denatured DNA from each was immobilized on nitrocellulose membranes and reassociated with labeled probe DNAs from egg endosymbionts and muscle nuclei of B. orientalis. The DNAs were compared by extent of binding and by the thermal melting profiles of the DNA duplexes. The DNAs from the endosymbionts in the eggs and fat body in both P. americana and B. orientalis were shown to be virtually identical, confirming that transovarial transmission of the bacteria does take place. The thermal stabilities of the heteroduplexes formed with the probe DNA from egg endosymbionts of B. orientalis differed from the homologous duplexes by only 1°–11°C, indicating a close relationship among the endosymbiont strains. The heteroduplexes of the nuclear DNAs differ from the homologous duplexes by 2°–7°C. Compared with known systems in bacterial and Drosophila species, these results indicate similar base-pair mismatches for host and endosymbiont DNAs. From these correlations, we deduce that the endosymbionts have probably been associated with their host cockroaches since before the latter speciated.     

Mixed IgA-IgG aggregates as a model of immune complexes in IgA nephropathy

Patients with IgA nephropathy have circulating immune complexes containing IgA, IgG, and C3. We have mixed human IgG and IgA1 and heated them to form mixed aggregate. On sucrose density gradients IgG aggregates were 11 to 19S whereas IgA aggregates were either 11S or greater than 19S. Mixed aggregates had both an 19 and 11 S peak. The isoelectric point of aggregates with only IgG was 7 to 9 and of only IgA 4.5 to 5.5. The isoelectric point of mixed aggregates decreased as the percent IgA increased. IgG aggregates mixed with normal human serum caused 30% C3 activation (20 min, 37 degrees C) whereas IgA aggregates causes no activation. There was a linear decrease in C3 activation as the percent IgA increased. Mixed aggregates that contained either radiolabeled IgG or IgA were mixed with normal human serum (1 h, 37 degrees C) and then solubilized, reduced, and separated by 10% SDS-PAGE. Heavy m.w. bands, consistent with covalent bonding of C3b and C3bi to Ig H chain were only seen in lanes with labeled IgG. This was confirmed by Western blot analysis. A human dimeric IgA1 myeloma protein with rheumatoid factor activity was also studied. It caused 15% alternative pathway C3 activation but did not fix C3 to its H chain. Binding of aggregates (+/- C3) to E was tested. Aggregates with IgG C3 bound but IgA (+/- C3) did not. Addition of greater than 10% IgA to an IgG-C3 aggregate inhibited E binding. We conclude that IgG in mixed aggregates is the site of C3 fixation. In contrast, IgA does not fix C3 but instead lowers the isoelectric point, increases the size and inhibits binding to E. These properties would inhibit clearance and promote mesangial deposition and local C activation.     

Attachments by parasitic lampreys within the branchial cavities of their hosts

Silver Lamprey (Ichthyomyzon unicuspis) in the Wisconsin River attached within the branchial cavity of Paddlefish (Polyodon spathula) significantly more often (6.5% of 1,578 attachments) than would be expected by chance on the basis of its relative surface area (3.7%), with as many as four lampreys found together within the branchial cavity of the same Paddlefish. Similar behavior has occasionally been noted for lampreys in other systems, but the phenomenon may be underreported when the lampreys are concealed from view. As suggested previously for some parasitic trychomycterid catfishes, lampreys in the branchial cavity may benefit from accessing blood under pressure, especially in the ventral aorta. In addition, Silver Lamprey within the branchial cavities of Paddlefish may be relatively protected from any negative effects that might result from Paddlefish breaching.     

Wingbeat frequency and flap-pause ratio during natural migratory flight in thrushes

Powered flapping flight has evolved independently in many differenttaxa. For flapping fliers, wingbeat parameters such as frequencyand amplitude are the primary determinants of these animals’energetic expenditure during flight. Here we present data onwingbeat frequency and amplitude for three New World thrushspecies during 15 entire nocturnal migratory flights over theMidwestern United States. Using continuous (non-pulsing) radiotransmitters, we were able to measure wingbeat frequency andrelative amplitude of wingbeats as well as the characteristicsof flap-pauses. Contrary to previous telemetric findings, allof the individuals we followed used both flapping-only and flap-pauseflight. During migratory flights, wingbeat frequency, effectivewingbeat frequency, and amplitude were highest during initialascent. Effective wingbeat frequency and amplitude were lowestduring final descent. We show that identification of speciesbased solely on characteristics of the wingbeat e.g., duringradar studies, can be difficult because variables such as wingbeatfrequency and amplitude, wingbeat pausing, and pattern of beatsand pauses vary between individuals of the same species andeven within individual flights. We also show that observed wingbeatfrequencies were lower than those predicted by theoretical models.We speculate that this may be because theoretical predictionsare generally based on (1) data from larger birds and (2) datafrom diurnal flights. We found that diurnal wingbeat frequenciesof thrushes were generally higher than were those during nocturnalmigratory flight. Finally, we suggest that rather than remainingat a single altitude during flight or climbing slightly as theoreticalmodels predict, thrushes often moved up and down in the aircolumn, perhaps searching for favorable atmospheric conditions.