Effect of Conditioned Media from Several Cell Types on Invasion by Eimeria adenoeides Sporozoites1

ABSTRACT. The effect of conditioned media (media aspirated from a variety of cell cultures after 4 d of growth) on cellular invasion by sporozoites of the turkey coccidium, Eimeria adenoeides, was examined. Conditioned medium from turkey kidney cells and baby hamster kidney cells failed to alter invasion. However, conditioned medium from turkey cecal cell cultures produced a significant (P ≤ 0.05), two-fold increase in invasion over control medium in a variety of cell types. Retentates of conditioned medium from the turkey cecal cells that were passed through microconcentrators having molecular mass cutoffs of 50, 100, and 300 kDa similarly enhanced invasion over retentates from control medium. However, retentates from microconcentrators with a cutoff of 1,000 kDa failed to enhance invasion. Pretreatment in conditioned medium, followed by washing of sporozoites prior to inoculation into cultures, did not result in enhanced invasion. Moreover, when the interval between inoculation of sporozoites into cells and fixation of cultures was reduced to less than 3 h, no enhancement of invasion occurred. Conditioned medium from turkey cecal cells that were grown in the presence of ³⁵S-translabel had at least two labeled bands at 150 kDa and > 200 kDa that were absent in conditioned media from turkey kidney and baby hamster kidney cells.     

Identification of amino compounds synthesized and translocated in symbiotic Parasponia

We investigated the synthesis and translocation of amino compounds in Parasponia, a genus of the Ulmaceae that represents the only non-legumes known to form a root nodule symbiosis with rhizohia. In the xylem sap of P. andersonii we identified asparagine. aspartate. glutamine, glutamated significant quantities of a non-protein amino acid. 4-methylglutamte(2-amino-4-methylpentanedioic acid). This identification was confirmed by two methods, capillary gas chromatography (GC) electron ionization (El) mass spectrometry (MS) and reverse phase high pressure liquid chromatography (HPLC) analysis of derivatized compounds. In leaf, root and nodule samples from P. andersonii and P. parviflora we also identified the related compounds 4-methyleneglutamate and 4-methyleneglulamine. Using ¹⁵N₂ labelling and GC-Ms analysis of root nodule extracts we followed N₂ fixation and ammonia assimilation in P. andersonii root nodules and observed Label initially in glutamine and subsequently in glutamate, suggesting operation of the glutamine synthetase/glutamine:2-oxoglutarate aminotransferase (GS/GOGAT) pathway. Importantly, we observed the incorporation of significant quantities of ¹⁵N into 4-methylglutamate in nodules, demonstrating the de nova synthesis of this non protein amino acid and suggesting a role in the translation of N in symbioticParasponia.     

Microgeographic distribution of immature Ixodes dammini ticks correlated with that of deer

In order to determine whether the small-scale distribution of immature Ixodes dammini Spielman et al. corresponds closely to the activity patterns of white-tailed deer, Odocoileus virginianus (Zimmerman), these relationships were examined in a site on Long Island, New York, U.S.A. We first determined the extent and temporal pattern of adult ticks feeding on deer by examining twenty-three resident deer tranquilized during September-December 1985. I. dammini adults infested deer throughout this fall period, most abundantly during October and November. With radio-telemetry collars attached to deer we determined the relative frequency that they occupied 0.25 ha quadrats of the study site. During the following summer, we examined white-footed mice, Peromyscus leucopus (Rafinesque), that inhabited these quadrats and removed immature ticks from each. 8975 larval and 163 nymphal I. dammini were removed from 208 mice trapped in forty-three such quadrats. The frequency of deer using these quadrats was positively correlated with both the number of larval and of nymphal ticks per mouse. These results suggest that risk of I. damminiborne zoonotic disease may be decreased by locally reducing deer density in sites that experience intense human activity.     

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.

     

Plant Growth Analysis: a Program for the Fitting of Lengthy Series of Data by the Method of B-splines*

A method is presented for fitting curves to lengthy and/or complicatedseries of data on plant growth. A computer program which derivesthe usual plant growth analytical quantities, and their errors,from these fitted curves is also described and offered for circulation.The fitted curves are splined cubic polynomial exponentials.Examples of their application are given, employing both realand artificial data. In any set of data the number of splines,and the position of the knots joining them, may be determinedeither by objective statistical tests or by the experimenterhimself, who thus retains a considerable degree of control overthe process but can call on the assistance of the program ifrequired. The value of this method is considered in relationto other curve-fitting approaches to plant growth analysis andit is concluded that, provided sufficient primary data are available,the method is free from many of the problems which beset earlierwork in this field, and also provides new possibilities of itsown. growth curves, approximating functions, empirical models, regression analysis, growth analysis     

A note on combining two methods of dispersal-for-distance

We ask under what circumstances two methods of dispersal-for-distance should be combined, given that the second method may carry the diaspore back towards its point of origin. The combination is made possible when the morphological adaptations of the diaspore are compatible. It is advantageous when the return on investment in the first method of dispersal declines sharply beyond some level of investment. The median seed achieves the best net distance when the two methods achieve similar distances; the upper decile of seeds achieve nearly a simple sum of the two distances. The first two conditions apply to the combination of ballistic with ant-dispersal, which is widespread in Australian sclerophyll shrubs. Mother plants’fitnesses could well be determined by the upper decile of distances their seeds achieve. It remains an open question whether the addition of ant-dispersal to ballistic dispersal achieves the selective advantage of distance or of placement.     

The feeding and ranging behaviour of Galapagos giant tortoises (Geochehne elephantopus) The Cambridge and London University Galapagos Expeditions, 1972 and 1973

Field observations on the behaviour of adult Galapagos giant tortoises ( Geochehne elephantopus ) on the islands of Santa Cruz (Indefatigable) and Pinzon (Duncan) were made by the 1972 Expedition, and on Santa Cruz by the 1973 Expedition. The animals (in all 14 on Santa Cruz and three on Pinzon) were observed continuously throughout the day for periods of 3–14 days so that their main non-reproductive activities (feeding and walking) could be quantitatively recorded. The period of potential activity was between about 08.00 hrs and 16.00–18.00 hrs, but the pattern of behaviour was extremely variable, both in a given individual and between one individual and another; it seemed little influenced by the relatively slight fluctuations of temperature and climate which occurred during the period of study (July-September) on Santa Cruz. The tortoises on Pinzon, a much more arid island, were less active, and one showed a strongly bimodal activity pattern with a resting period during the middle of the day. The animals studied in 1972 showed a strong disposition to return after several days to the same sleeping place, but this homing tendency was not observed in 1973. This discrepancy can perhaps be attributed to the fact that the two expeditions worked in different areas under different weather conditions. Observations on the plants eaten, on the association between tortoises and certain birds, and on some other aspects of tortoise behaviour such as walking speed and responses to sounds are also described.