Late Mississippian to Early Pennsylvanian conodont biofacies in central Montana

Later Mississippian (upper Chesterian) to Early Pennsylvanian (lower Morrowan) conodont faunas were recovered from limestones and calcareous mudstones of the Alaska Bench Formation in central Montana. These faunas define four biofacies, each recognized by the dominance of a particular single element genus for which the biofacies is named. The Adetognathus biofacies represents lagoonal, tidal flat, and barrier sediments. The Declinognathodus/Idiognathoides biofacies represents a deposition in shallow, open marine, offshore conditions. The Rhachistognathus biofacies represents a transitional environment between restricted, intertidal environments and normal marine, offshore environments. The Neognathodus biofacies represents shallow-water bay or lagoonal deposition, where environmental controls have effectively excluded other conodont faunas. The investigation of conodont biofacies provides improved biostratigraphic and paleoenvironmental uses of conodonts.     

Trypanosoma brucei: Differentiation of in Vitro-Grown Bloodstream Trypomastigotes into Procyclic Forms1

Trypanosoma brucei strain 366D trypomastigotes grown at 37°C in the presence of a human fibroblast cell line formed foci underneath the feeder cells whereas trypanosomes grown in the presence of a human epithelial cell line grew only in the culture supernatant. A culture system was developed to study the differentiation of bloodstream trypomastigotes grown in the epithelial cell system into procyclic trypomastigotes at 27°C. The morphological differentiation into the procyclic form was complete by 48 h. Cell division did not occur until 30–40 h after transfer to 27°C. Various characteristics of this system were examined, including the effect of the feeder layer, the type of medium, the presence of the metabolites cis-aconitate and citrate, the preadaptation period, and the trypanosome cell concentration. The respiration of the recently differentiated procyclic cells was less sensitive to inhibition by CN-than that of established procyclic forms, implying a delayed appearance of complete mitochondrial oxidative pathways. This trypanosome differentiation system has the advantage that the animal host is not needed and the entire process is carried out in in vitro culture.     

Association between microtubules and symbiotic fungal hyphae in protocorm cells of the orchid species, Spiranthes sinensis

Seeds of the orchid species, Spiranthes sinensis (Pers.) Ames, were sterilized and germinated in vitro with the symbiotic fungus Ceratobasidium cornigerum (Bourdot) Rogers. Colonized embryos developed into protocorms and these were examined for changes in microtubule arrays, after initial invasion of fungal hyphae into embryos and during peloton formation and degradation. Methods utilized to detect microtubules included immunofluorescence combined with laser scanning confocal microscopy, conventional transmission electron microscopy combined with morphometric analysis, and immunogold labelling. Microtubules were regularly found in close association with intracellular hyphae and degraded hyphal masses. Cortical microtubules disappear during peloton formation but reappear in cells that show fungal lysis. With conventional transmission electron microscopy and immunogold labelling the microtubules associated with fungal hyphae and degenerated hyphal masses were located close to the perifungal membrane that separates fungal hyphae from protocorm cytoplasm.     

A new genus and two new species of Choniostomatidae (Copepoda) parasitic on two deep sea isopods

The systematic position of the little-deformed parasitic copepod family Nicothoidae to the much deformed family Choniostomatidae has been disputed for many years. The new genus Diexanthema gen. nov., based on Diexanthema desistoma sp. nov. and Diexanthema bathydiaita sp. nov. discovered on two deep-sea asellote isopod species, clearly links the family Nicothoidae (via male Diexanthema) to the family Choniostomatidae (via female Diexanthema). Based upon the extreme sexual dimorphism of this new genus, it is suggested that the family Nicothoidae be dissolved and its members placed within the family Choniostomatidae. It is concluded that the differences seen between these two parasitic groups is probably due more to host adaptations than reflecting any phylogenetic trend that is evolutionarily significant. It is felt that the deep-sea environment may serve as a refugium for archaic copepod forms which may possibly offer additional clues and insights into the phylogeny of the parasitic copepoda.
This investigation suggests that the life history and parasite/host relationships of Diexanthema desistoma are quite complicated and well geared to the life history of its isopod host, Chelator insignis.     

Models and Evidence for Feeding Control of Energy

The value of optimization theory is to provide falsifiable hypothesesand, when appropriate, alternative models of resource regulation.A consideration of alternatives suggests optimal energy regulationthrough feeding depends on time scale and supplies of energyrelativeto demands. Maximization (on-off) control of energyreserves occurs over short intervals involved in consumption,while proportional control occurs over longer intervals (betweenmeals) or as a consequence of trade-offs between energy regulationand nutrient or predation constraints. Maximization of rateof net energy gain occurs most frequently when energy suppliesare low relative to demands and when energy and nutrients arenot associated. This may be typical for small endothermic nectarfeeders, while proportional controls are characteristic of feedingbehaviors for many other animals. Controls for regulating energycontent must also be affected by external environmental variationwhich may require use of "rules of thumb" that approximate themaximum rate of return.     

The Inhibition by Cytokinin of Auxin-Promoted Elongation in Excised Soybean Hypocotyl

The experiments characterize the inhibition by kinetin of auxin-promoted elongation in excised hypocotyl sections of 3-day soybean seedlings (Glycine max cv. Hawkeye 63). It was found that concentrations of kinetin above 4.2 μM did not further inhibit auxin-promoted elongation. Kinetin is as potent an inhibitor of elongation as actinomycin D or cycloheximide. Tissue incubated for 3 or 5 h in the absence of auxin or cytokinin would, upon addition of auxin, exhibit a new growth rate similar to that of tissue grown in auxin for the entire incubation period. Similarly, tissue grown for 3 and 5 h in the presence of auxin would revert to the control rate of elongation upon addition of kinetin. A 10 to 30 min preincubation in kinetin yielded the tissue incapable, for the ensuing 6 h, of increasing its rate of elongation in response to auxin. Zeatin and isopentenyladenine were more potent than kinetin and benzyladenine in the inhibition of elongation. Levels of ethylene produced in the presence of auxin plus cytokinin indicated that it was not involved in this auxin-cytokinin interaction. Kinetin by itself did not promote elongation; nor did it enhance auxin-promoted elongation at low auxin concentrations.     

The Arrhenius Equation as a Model for Explaining Plant Responses to Temperature and Water Stresses

The Arrhenius equation describes the response of biologicalprocesses to temperature. This study was conducted to examinethe applicability of the Arrhenius equation to whole plant processesand to explore the application of the Arrhenius equation asa basis for characterizing plant responses to water stress.Rates of growth of leaf area and shoot dry mass of spring wheatseedlings were measured at combinations of five soil water potentials(–0.03, –0.06, –0.10, –0.17 and –0.25MPa) and seven root temperatures (12, 14, 17, 22, 27, 29 and32 C). A non-linear least square procedure was used to fitthe modified Arrhenius equation to experimental observations.Adequate distribution of experimental observations with respectto temperature reduces the uncertainties in parameter evaluations.The standard error of the estimate of optimum temperature forleaf area growth increased from 1.4 C to 6.3 C when one ofthe data points was omitted. The optimum temperature and theenthalpy of denaturalization of enzyme systems were independentof soil water potential. A linear relation was found betweenthe rate constant and the activation energy: The Arrhenius equation was modified using this linear relation,leaving the activation energy as the only parameter affectedby water stress. The activation energy increased linearly assoil water potential decreased, with slopes of –27.18 10₃ and –28.09 10₂ K MPa^–1 for the rates ofgrowth of leaf area and shoot dry mass, respectively. Theseslopes could be used as indicators of the sensitivity of plantprocesses to water stress. Temperature, water, plants, Arrhenius equation     

Recruitment, Search Behavior, and Flight Ranges of Honey Bees

During the past three decades, considerable evidence has beengathered in attempts to understand more fully honey bee recruitmentto food sources. Those efforts also apply directly to two long-standingand competing recruitment hypotheses: odor search vs. "dancelanguage" communication. However, whereas most researchers havefocused on individual interactions and behavior, the colonycan also be viewed as a unit. A review of evidence from a colonyperspective reveals that colony members range an average distancefrom their home base, whether while foraging on food sources,while collecting water, or while relocating as swarms. Thoseaverages, based on the logarithm of the distance from the colony,vary with the type of resource exploited and size of the odorfield. Such a mathematical correspondence between distancestravelled from parent colonies may well agree with an odorsearchrecruitment model, but is hardly reconcilable with the "dancelanguage" hypothesis.     

Eimeria balphae n. sp. from the Ord Kangaroo Rat Dipodomys ordii*

SYNOPSIS. Eimeria balphae n. sp. is described from the Ord kangaroo rat Dipodomys ordii. The sporulated oocysts are broadly ellipsoidal to ovoid, averaging 16.7 by 14.3 μ. A single, large, homogenous body represents the oocyst residuum. A polar granule is present. There is no micropyle. The ovoid sporocysts average 8.7 by 5.9 μ. The sporocyst residuum is composed of 7–14 round, clear granules. This species of Eimeria was found in 1 of 82 D. ordii in northwestern Utah.