Thermal Dependence of Tongue-flicking and Comments on Use of Tongue-flicking as an Index of Squamate Behavior

Tongue-flicking rate has often been used as a dependent variable or a component of a dependent variable taken as a measure of responsiveness to chemical stimuli by lizards and snakes. Because temperature has been controlled in most studies, effects of temperature have been largely overlooked. In this study, a constant stimulus, the adult cloacal odor of a conspecific female, was presented to adult scincid lizards (Eumeces laticeps) and temperature was from 15 ° to 35 °C. Tongue-flicking rates by adult Eumeces laticeps in response to cloacal odors of conspecific females were strongly thermally dependent in 20 s and 60 s trial periods. The tongue-flick-temperature curve appears to be roughly quadratic over the entire 15 °-35 °C range studied, with very low rates at 15 ° and 20 °C followed by a rapid rise to maximum tongue-flicking rate at 30 ° and rapid decline to 35 °C. Presumably, similar relationships apply to other lizards and snakes with modifications related to ecological characteristics such as diel activity cycle and foraging mode, to relative position on a scale of eurythermy-stenothermy, and to taxon. Thermal response curves for other stimuli, especially prey odors, are likely to have the same basic form, but have not been determined.     

Compartmentation of glutamate metabolism in brain. Evidence for the existence of two different tricarboxylic acid cycles in brain

1. (14)C from [1-(14)C]glucose injected intraperitoneally into mice is incorporated into glutamate, aspartate and glutamine in the brain to a much greater extent than (14)C from [2-(14)C]glucose. This difference for [1-(14)C]glucose and [2-(14)C]glucose increases with time. The amount of (14)C in C-1 of glutamate increases steadily with time with both precursors. It is suggested that a large part of the glutamate and aspartate pools in brain are in close contact with intermediates of a fast-turning tricarboxylic acid cycle. 2. (14)C from [1-(14)C]acetate and [2-(14)C]acetate is incorporated to a much larger extent into glutamine than into glutamate. An examination of the time-course of (14)C incorporated into glutamine and glutamate reveals that glutamine is not formed from the glutamate pool, labelled extensively by glucose, but from a small glutamate pool. This small glutamate pool is not derived from an intermediate of a fast-turning tricarboxylic acid cycle. 3. It is proposed that two different tricarboxylic acid cycles exist in brain.     

AdaptivSearch: A Novel Iterative Algorithm for the Generation of n-dimensional Hypersurfaces Using an Adaptive Numerical Strategy

AdaptivSearch is the first adaptive strategy based algorithm for the rational and economical construction of n-dimensional hypersurfaces. AdaptivSearch works iteratively: At each step it parcels out the definition range into several triangles, evaluates the worst according to a built-in error criterion, and refines the approximation to the unknown function by choosing the barycenter of this partial area as the node to be calculated next. Based upon the error criterion, AdaptivSearch selectively approaches those parts of the hypersurface in which the curvature exhibits the strongest changes. Some examples of AdaptivSearch applications for both analytical functions and chemical model surfaces are given in order to demonstrate the behavior of the algorithm. These show its broad applicability and the usefulness, especially for chemical problems.     

Reduction of food intake and weight gain by the ob protein requires a specific secondary structure and is reversible.

BACKGROUND: Obesity, the condition of excessive accumulation of fat is a poorly understood disorder and is a risk factor for type II diabetes, hypertension, and hyperlipidaemia. Recently, a putative mouse obese gene was cloned and its product, termed ob protein, was shown to be involved in the regulation of body weight. MATERIALS AND METHODS: Bacterial and insect cells were used for expression of recombinant mouse ob protein. Amino-terminal sequence analysis and site-directed mutagenesis were used to identify and characterize the mature form of ob protein. Genetically obese mice and wild-type rats were used to determine the biological activity of ob protein. RESULTS: Mouse ob protein is synthesized as a precursor molecule, the mature form of which was found in mouse serum. Biochemical analysis identified the processing site in the ob precursor molecule and an intramolecular disulfide bond in the mature form that is necessary for activity. Reduction of food intake and weight gain after administration of ob protein to genetically obese mice and wild-type rats is reversible. DISCUSSION: This study demonstrates that ob protein is a secreted satiety factor which regulates body weight and reduces food intake even in animals with no genetic body weight abnormalities. The failure of ob protein to effect these parameters in db/db mice supports the hypothesis that these mice are deficient in a signaling molecule that normally responds to the ob protein.     

Local differentiation and plasticity in size and sex expression in jack-in-the-pulpit, Arisaema triphyllum (Araceae)

The size advantage hypothesis suggests that natural selection will favor size-dependent sex expression when one sex gains more than the other by being large. But members of a minority sex will also have a higher reproductive value, on average. Thus, an individual's reproductive success depends on the reproductive decisions made by neighboring individuals. As a result, the optimal relationship between size and sex may differ among populations. In Arisaema triphyllum, the probability for an individual to be female increases with size, regardless of the character measured. A reciprocal transplant experiment showed the relationship between size and sexual expression is environmentally plastic. Plants originating from our two study sites became female at a larger average size when grown at one site than when grown at the other. In addition to environmental influence on sex expression, the experiment demonstrated genetic differences in the relationship between size and sex. Plants collected from one site became female at a larger size than those from the other, regardless of where they were grown. Thus, while the environment in which an individual was grown had a substantial influence on its sex expression, populations only a few kilometers apart have genetically different relationships between size and sex.     

Growth differentiation factor-9 stimulates proliferation but suppresses the follicle-stimulating hormone-induced differentiation of cultured granulosa cells from small antral and preovulatory rat follicles

In addition to pituitary gonadotropins and paracrine factors, ovarian follicle development is also modulated by oocyte factors capable of stimulating granulosa cell proliferation but suppressing their differentiation. The nature of these oocyte factors is unclear. Because growth differentiation factor-9 (GDF-9) enhanced preantral follicle growth and was detected in the oocytes of early antral and preovulatory follicles, we hypothesized that this oocyte hormone could regulate the proliferation and differentiation of granulosa cells from these advanced follicles. Treatment with recombinant GDF-9, but not FSH, stimulated thymidine incorporation into cultured granulosa cells from both early antral and preovulatory follicles, accompanied by increases in granulosa cell number. Although GDF-9 treatment alone stimulated basal steroidogenesis in granulosa cells, cotreatment with GDF-9 suppressed FSH-stimulated progesterone and estradiol production. In addition, GDF-9 cotreatment attentuated FSH-induced LH receptor formation. The inhibitory effects of GDF-9 on FSH-induced granulosa cell differentiation were accompanied by decreases in the FSH-induced cAMP production. These data suggested that GDF-9 is a proliferation factor for granulosa cells from early antral and preovulatory follicles but suppresses FSH-induced differentiation of the same cells. Thus, oocyte-derived GDF-9 could account, at least partially, for the oocyte factor(s) previously reported to control cumulus and granulosa cell differentiation.     

<Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> inhibits <Emphasis Type="Italic">in-vitro Candida</Emphasis> biofilm development

Background  

Elucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development.