Ontogeny of the Behavior of Strombus maculatus (Gastropoda: Strombidae)

The ontogeny of strombid behavior was studied by observing thebehavior of Strombus maculatus veligers collected from the planktonand reared past metamorphosis to adults, and by observing juvenilestrombids collected in the field. Complete adult modal actionpatterns (MAP's) associated with locomotion, feeding, and rightingof overturned shells are performed by S. maculatus juvenilesimmediately after metamorphosis. There are changes in the frequencyof the use of certain MAP's which are associated with variationsin shell shape and size. The unique strombid escape response to molluscivorous gastropods(Conns spp.) is not released until juvenile S. maculatus arethree weeks past metamorphosis and two millimeters in shelllength. At that stage, the complete response is released uponthe first encounter with a predator. Experience with a predatordoes not seem to lower the age or size criteria. During ontogeny there is a trend toward an increasing complexityof behavior which is paralleled by an increasing complexityof neural structure and general morphology. There are majorsteps in the ontogeny of strombid behavior which probably coincidewith neural and morphological stages.     

A Dynamic Growth Model of Vegetative Soya Bean Plants: Model Structure and Behaviour under Varying Root Temperature and Nitrogen Concentration

A differential equation model of vegetative growth of the soyabean plant (Glycine max (L.) Merrill cv. ‘Ransom’)was developed to account for plant growth in a phytotron systemunder variation of root temperature and nitrogen concentrationin nutrient solution. The model was tested by comparing modeloutputs with data from four different experiments. Model predictionsagreed fairly well with measured plant performance over a widerange of root temperatures and over a range of nitrogen concentrationsin nutrient solution between 0.5 and 10.0 mmol in the phytotron environment. Sensitivity analyses revealedthat the model was most sensitive to changes in parameters relatingto carbohydrate concentration in the plant and nitrogen uptakerate. Key words: Glycine max (L.) Merrill, dry matter, nitrogen uptake, partitioning, photosynthesis, respiration, sensitivity analysis     

Carbon Dioxide Effects on Carbohydrate Status and Partitioning in Rice

The atmospheric carbon dioxide (CO₂) concentration has beenrising and is predicted to reach double the present concentrationsometime during the next century. The objective of this investigationwas to determine the long-term effects of different CO₂ concentrationson carbohydrate status and partitioning in rice (Oryza sativaL cv. IR-30). Rice plants were grown season-long in outdoor,naturally sunlit, environmentally controlled growth chamberswith CO₂ concentrations of 160, 250, 330, 500, 660, and 900µmolCO₂ mol¹ air. In leaf blades, the priority between the partitioningof carbon into storage carbohydrates or into export changedwith developmental stage and CO₂ concentration. During vegetativegrowth, leaf sucrose and starch concentrations increased withincreasing CO₂ concentration but tended to level off above 500µmolmol^–1 CO₂. Similarly, photosynthesis also increased withCO2 concentrations up to 500µmol mol^–1 and thenreached a plateau at higher concentrations. The ratio of starchto sucrose concentration was positively correlated with theCO₂ concentration. At maturity, increasing CO₂ concentrationresulted in an increase in total non-structural carbohydrate(TNC) concentration in leaf blades, leaf sheaths and culms.Carbohydrates that were stored in vegetative plant parts beforeheading made a smaller contribution to grain dry weight at CO₂concentrations below 330µmol mol^–1 than for treatmentsat concentrations above ambient Increasing CO₂ concentrationhad no effect on the carbohydrate concentration in the grainat maturity Key words: CO₂ enrichment, starch, sucrose     

Annotated Index to Genera, Subgenera and Suprageneric Taxa of the Ciliate Order Tintinnida

SYNOPSIS. Supraspecific taxa of the ciliate Order Tintinnida Corliss, 1955 are indexed by 304 entries; genetic type species are cited with reference to the original citation. The accompanying bibliography of 133 entries includes those publications cited in the index. Authors for several type citations are corrected, as is authorship of some genera, and a new type designation is made for Parundella to replace the previous erroneous designation. Genera present in the fossil record are so indicated.