Dancing to the rhythms of geological time: the biorhythm capabilities of Polychaeta in a geological context

Summary

Errant polychaete worms in the Orders Eunicida (family Eunicidae) and Phyllodocida (families Nereidae and Polynoidae) exhibit a highly developed biorhythmic capability. The Pacific palolo worms are well known for a precisely timed annual breeding event in which mass spawning occurs at a particular time of day, on one day per year, that day having a fixed relationship to the lunar period. Nereidae and Polynoidae exhibit photoperiodic responses that determine the breeding season by regulation of oocyte growth. Nereis virens shows short-term cycles of foraging activity; automated recording of these patterns has revealed four distinct behaviour rhythm phenotypes: circadian, tidal, lunidian and arrhythmic, the last phenotype being expressed during the photoperiod induced growth diapause. The Eunicids and Phyllodocids are represented in the fossil record by scolecodonts, their fossilised jaws. There was a major radiation of these polychaetes during the Ordovician and the earliest suggested polychaete fossils are from the Cambrian. The simultaneous expression of tidal and circadian rhythmicity is characteristic of intertidal animals and it is likely that this complex behavioural repertoire was found in the ancestors of modern terrestrial forms, such as tetrapods and arthropods, prior to their emergence onto land during the Carboniferous and Silurian periods at least 400 Ma. The period of the earth's rotation, and hence day length and tidal period, has long been known to be increasing, and additionally the moon to be retreating from the earth, due to the phenomenon of tidal friction caused by the gravitational interactions between the moon and the earth. These changes are significant over a geological time scale. Consequently, the length of day was substantially less (and the number of days in a year more) than at present in the Cambrian and Ordovician periods. Recent theoretical analysis of the period of the earth's rotation suggests that the day length prior to a critical period (t _crit ) around 1800 Ma may have been stable, with a length of only 4 h. At that time a period of more rapid change in the dynamics of the rotation was initiated. The implications of this theory for the evolution of the biological clock are discussed.     

In Vitro Excystation of Caryospora simplex (Apicomplexa: Eimeriorina)1

In vitro excystation of sporozoites of the heteroxenous coccidian Caryospora simplex Léger, 1904 (Apicomplexa: Eimeriorina) is described. Sporocysts freed mechanically from oocysts released a maximum of 51% of their sporozoites within 45 min at 25°C and a maximum of 74% within 20 min at 37°C when incubated in a 0.25% (w/v) trypsin–0.75% (w/v) sodium taurocholate (bile salt) excystation solution. At emergence from sporocysts, sporozoites were weakly motile then became highly active after about 2 min in excystation solution. Sporozoites within sporocysts exposed to bile salt only became highly motile within 25 min at 25°C and within 15 min at 37°C but did not excyst. When exposed only to trypsin at the above temperatures, the Stieda body dissolved; the substieda body remained intact, and the sporozoites exhibited only limited motility within sporocysts; only a few excysted. Intact, sporulated oocysts incubated at 25° or 37°C in 0.02 M cysteine-HC1 and a 50% CO₂ atmosphere for 18 h had no morphologic changes in the oocyst wall. Further incubation of these intact oocysts in excystation solution for 30 min at 37°C caused neither motility of sporozoites within sporocysts nor excystation. Grinding oocysts for 30 sec in a motor-driven, teflon-coated tissue grinder caused motility of some sporozoites within sporocysts but did not result in excystation.     

IDENTIFICATION AND EVALUATION OF THE FLAVOR-SIGNIFICANT COMPONENTS OF GINGER ESSENTIAL OIL

The flavorfully significant compounds in ginger essential oilwere selected statistically by use of a step-wise multiple regressionanalysis which treated individual peak quantitities on a gaschromatogram as independent variables and taste panel scoresfor ginger flavor intensity as dependent variables. The statisticalanalysis showed that four gas chromatographic peaks, consistingof a terpineol, citral a, citral b (peak 11), ß-sesquiphellandrene,ar-curcumene (peak 14), nerolidol (peak 19), and a sesquiterpenealcohol (peak 29), accounted for 85% of the panel's flavor response(R²=0.85). Taste panel evaluations of the isolated components indicatedthat ß-sesquiphellandrene and ar-curcumene are theprime contributors to the characteristic ‘ginger’attribute. -Terpineol, citral a and citral b contribute to the‘lemony’ attribute of ginger oil and may thereforebe desirable additives to whole ginger oil to intensify its‘lemony’ character. Nerolidol contributes to the‘woody’ or ‘soapy’ attribute and doesnot appear to be a good potential additive to ginger oil. A trained sensory panel judged a mixture of -terpineol, citrala, citral b, ß-sesquiphellandrene, ar-curcumene andnerolidol to be characteristic of ginger oil. The panel founda mixture of these chemicals, in combination with ginger heatchemicals, to be a suitable imitation ginger flavor. The study has shown that statistics can be used in selectingthe individual flavor contributing components of a flavor essence.This approach can greatly reduce the number of compounds whichneed be identified in the investigation of the composition ofnatural flavoring substances. ^* Scientific Article No. A1996, Contribution No. 4938, MarylandAgricultural Experimental Station (Food Science Program).     

Role of GTP in the Positioning of Formylmethionyl-tRNA<Subscript>f</Subscript> on the <Emphasis Type="Italic">E. coli</Emphasis> Ribosome

FORMATION of the E. coli initiation complex between ribosomal subunits, natural messenger RNA and formyl-methionyl-tRNA_f (fMet-tRNA_f) requires the presence of initiation factors and GTP^1–3. In the binding reaction, GTP can be replaced by an analogue, guanylyl-5′-methylene-diphosphonate (GMP-PCP), but the complex does not then react with puro-mycin. Hydrolysis of GTP is therefore required for the formation of an active initiation complex able to carry out peptide bond formation⁴.     

Hammondia pardalis sp. n. (Sarcocystidae) from the Ocelot, Felis pardalis, and Experimental Infection of Other Felines

Synopsis.
Hammondia pardals sp. n. (Eimeriorina: Sarcocystidae) from Panama Canal Zone is described as an obligate heteroxenous coccidian, with felids as the final host and laboratory mice as the experimental intermediate host. Ovoid oocysts. measuring 40.8 (36–46) × 28.5 (25–35) m. are shed unsporulated. Oocysts were infective only for the intermediate host. the laboratory mouse, Mus musculus , and the intracellular cysts were infective only for felids. Attempted passage of tissue cysts from mouse to mouse was unsuccessful.
Mice fed 5 × 10⁴ sporulated oocysts were found to harbor small intracellular cysts, 13–16 × 10–15 m, in the mesenteric lymph nodes, lungs, and intestinal submucosa 15 days postinfection. The meronts in these early cysts were stubby and measured 3 × 6 m. The prepatent period in the felids was 5 to 8 days and the patent period 5–13 days. Experimental infections of definitive hosts were successful with 6/6 domestic laboratory-reared kittens, Felis catus ; 5/5 ocelots, F. pardalis ; and 1/1 jaguarundi, F. yagouaroundi. None of the exposed raccoons, Procyon lotor , shed oocysts.     

Eimeria reedi sp. n. and E. chobotari sp. n. (Protozoa: Eimeriidae) from Heteromyid Rodents

SYNOPSIS The oocysts of 2 new species of Eimeria are described from heteromyid rodents. The subspherical to ellipsoidal cocysts of Eimeria reedi from Perognathus formosus averaged 22.6 by 20.8 μ. An ellipsoidal polar granule was present. The oocyst residuum was a single globule about 8 μ in diameter. The ovoid sporocysts averaged 10.9 by 7.7 μ and had a residuum of 6-12 granules. A Stieda body and substiedal body were present in the sporocysts. Eimeria chobotari oocysts, from Dipodomys merriami and D. microps , were ellipsoidal to ovoid and averaged 47.7 by 35.2 μ. No polar granule was seen. The large oocyst residuum consisted of several granules of various sizes. The ovoid sporocysts averaged 15.8 by 11.3 μ and had a residuum of many small granules. A Stieda body and substiedal body were present in the sporocysts.     

Provisional classifications v standard avian sequences: heuristics and communication in ornithology

The past decades have been exciting ones for ornithologists interested in avian macrosystematics with many new ideas being proposed for consideration and further study. But this excitement should not blind ornithologists to the important distinction between the provisional classifications proposed by specialists in macrosystematics, no matter how convincing they may appear at first glance, and the standard sequence needed to maintain optimal communication among all students of avian biologists. An excellent standard sequence for Recent birds exists in Peters' Check-list . We urge that all ornithologists, authors and editors use this sequence until the time arrives, as it undoubtedly will, when enough is known about avian relationships to permit agreement on a new and better standard sequence.     

THE APPLIED BIOLOGIST, THE CHILD, AND SOCIETY

Consideration of the characteristics of past and current applied biology reveals its fundamentally ecological nature, and also indicates the potent influence of the applied biologist upon society. It is urged that in order to impress influence upon pupils biological education should be based mainly upon field studies, rather than upon predominantly evolutionary, morphological and physiological studies. The nature of past and existing school biology strongly reinforces the abovel conclusion.
The results of attempts to find and evaluate evidence of the social influences of past and present biological education are presented, both in relation to the whole population, as well as to particular aspects, like food poisoning, the press, and the education of Civil Servants and Members of Parliment.
The potentialities of a Sixth Form biology resting chiefly upon field study are discussed not only as a means of developing an outlook valuable to-day, but also of treating suitably the pre-university education of future applied biologists.