Use of Flower Color-Cue Memory by Honey Bee Foragers Continues when Rewards No Longer Differ between Flower Colors

Honey bees (Hymenoptera: Apidae) were used as a model insect system to explore forager use of a learned color-cue memory over several subsequent days. Experiments used artificial flower patches of blue and white flowers. Two experiments were performed, each beginning with a learning experience where 2 M sucrose was present in one flower color and 1 M sucrose in the alternative flower color. The first experiment followed flower color fidelity over a series of sequential days when rewards no longer differed between flowers of different color. The second examined the effect of intervening days without the forager visiting the flower patch. Results showed that color-cue memory decline was not a passive time-decay process and that information update in honey bees does not occur readily without new experiences of difference in rewarding flowers. Further, although the color cue learned was associated with nectar reward in long term memory, it did not seem to be specifically associated with the 2 M sucrose nectar reward when intervening nights occurred between learning and revisiting the flower patch.     

Tumor DNA circulating in the plasma might play a role in metastasis. The hypothesis of the genometastasis.

BACKGROUND: Clinical and experimental observations suggest that more than one pathway might be involved in the development of metastases. In the present study, we examined the presence of tumor DNA in plasma using an experimental model in which tumor cells were modified with a genome-associated tag. We also investigated whether plasma of tumor-bearing rats had any effect on cultured cells and healthy animals. METHODS: Transfected cancer cells (DHD/K12-PROb stably transfected with pCDNA3.1CAT.) were injected subcutaneously into the chest of BD-IX rats. Animals were divided into ten groups according to the time between injection of tumor cells and euthanasia. Prior to euthanasia (2-14 week), blood samples were collected by cardiac puncture. To detect circulating tumor cells and CAT-encoding DNA in plasma, we performed PCR with nested primers. Fifty samples of plasma were chosen at random to supplement the medium of fifty cultures of DHD cells for 10-12 days. PCR for the detection of CAT DNA in cells was performed approximately one to two months later. Four healthy rats received an intraperitoneal injection of plasma from a tumor-bearing rat five times at week for 4 to 6 weeks. Animals were sacrificed and samples of liver, kidney, spleen, omentum, blood and lung were processed by PCR for the detection of CAT DNA. RESULTS: Detection of CAT DNA in plasma was slightly more frequent than in the buffy-coat fraction. All surviving cultures that had been supplemented with plasma were positive at some point for CAT DNA. In all four healthy animals injected with plasma of tumor-bearing rats, the marker gene for CAT was found in extracts of lungs. CONCLUSION: Our present observation lead us to propose the following hypothesis. Metastases might develop as a result of transfection of susceptible cells in distant target organs with dominant oncogenes that are present in the circulating plasma and are derived from the primary tumor.     

Blood biochemical polymorphism in Spanish goat breeds

1. The structure of the Pirenaica, Verata, Guadarrama, Zamorana, Berciana, Granadina, Blanca Andaluza, Blanca Celtibérica, Murciana, Negra Serrana, Malague?a, Canaria, Palmera and Retinta goat breeds have been analysed. 2. Fourteen blood genetic systems were analysed: reduced glutathione (GSH), red cell potassium (Ke), haemoglobin (Hb), diaphorase (Dia), catalase (Ct), malate dehydrogenase (MDH), carbonic anhydrase (CA), X-protein (X), nucleoside phosphorylase (NP), alkaline phosphatase (Alp), amylase (Am), ceruloplasmin (Cp), transferrin (Tf) and albumin (Al). 3. Of the fourteen genetic systems studied, six were monomorphic (GSH, Ct, MDH, CA, NP and Cp) and eight polymorphic (Ke, Hb, Dia, X, Alp, Am, Tf and Al). Phenotypic and gene frequencies of the eight polymorphic genetic markers are reported.     

An in situ enclosure experiment to test the solar UVB impact on plankton in a high-altitude mountain lake. I. Lack of effect on phytoplankton species composition and growth

The effect of solar UVB radiation on the growth and speciescomposition of phytoplankton from a high-mountain lake (2417m a.s.l.) was studied in situ for 16 days in two enclosuresof 1 m receiving either full sunlight or sunlight without UVB.A total of 20 species were identified in both enclosures, consistingmainly of dinoflagellates, chrysophytes and diatoms. Duringthe experiment, there were no significant differences in phytoplanktonspecies composition between the two enclos ures. In both treatments,the abundance of phytoplankton increased continuously, and chlorophylla changed by -5-fold. We observed high fluctuations in the abundanceof several species. However, these fluctuations occurred inboth enclosures, and hence they were not related to UVB radiation.Some species were affected by daily fluctuations of radiation(UVA + photosynthetically active radi ation). Cyclotella aff.gordonensis showed a robust positive correlation, whereas speciesof Gymno dinium were negatively correlated. For most species,the sensitivity to radiation found during the experiment wasconsistent with their diurnal vertical distribution in the lake.Our findings suggest that the phytoplankton from this very clearlake (10% of the surface UVB radiation at 305 nm reached 9.6m depth) were well adapted to the high UVB radiation charactensticof high-elevation sites.     

Prediction of the most favorable configuration in the ACBP-membrane interaction based on electrostatic calculations

Acyl-CoA binding proteins (ACBPs) are highly conserved 10 kDa cytosolic proteins that bind medium- and long-chain acyl-CoA esters. They act as intracellular carriers of acyl-CoA and play a role in acyl-CoA metabolism, gene regulation, acyl-CoA-mediated cell signaling, transport-mediated lipid synthesis, membrane trafficking and also, ACBPs were indicated as a possible inhibitor of diazepam binding to the GABA-A receptor. To estimate the importance of the non-specific electrostatic energy in the ACBP-membrane interaction, we computationally modeled the interaction of HgACBP with both anionic and neutral membranes. To compute the Free Electrostatic Energy of Binding (dE), we used the Finite Difference Poisson Boltzmann Equation (FDPB) method as implemented in APBS. In the most energetically favorable orientation, ACBP brings charged residues Lys18 and Lys50 and hydrophobic residues Met46 and Leu47 into membrane surface proximity. This conformation suggests that these four ACBP amino acids are most likely to play a leading role in the ACBP-membrane interaction and ligand intake. Thus, we propose that long range electrostatic forces are the first step in the interaction mechanism between ACBP and membranes.     

Frontal sinus ontogeny and covariation with bone structures in a modern human population

In humans, the frontal sinus (FS) is located in the medial part of the supraorbital region, sometimes expanded throughout the frontal squama. It exhibits high morphological variability, but its general form appears to be constrained by surrounding structures. The goal of this study is to analyze FS growth and test for covariation between FS volume and the glabellar region, upper nasal region, bone thickness and endocranial size in a human sample from Argentina. The sample comprises 149 reconstructions derived from computed tomography images of individuals aged 0–31 years. Volume of the FS and measurements of the surrounding structures were recorded. The FS growth trajectory was assessed by parametric and nonparametric methods, and covariation was determined using correlations and partial correlations. The FS volume could be measured at an age of about 6 years and older; adults had no aplasia but hyperplasia was found in some cases. Since the most conspicuous characteristic found was variation among individuals, the nonparametric smoothing spline produced very poor fitting. The modified logistic function was the only parametric method providing significant parameters. Sexes differed in the age at which FS growth began and ended, with FS developing earlier but at a slower rate in females than in males. The FS volume did not correlate with either upper nasal width or endocranial volume, but it correlated with bone thickness measurements (mainly from the glabellar region), even when age was held constant. Expansion of the FS at the frontal poles also correlated with frontal bone thickness. Despite the difficulty in modeling and predicting the trajectory and morphology of FS, our results suggest that it is affected by its surrounding bony environment.