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Dagmar Malun Martin Giurfa C. Giovanni Galizia Niels Plath Robert Brandt Bertram Gerber Beate Eisermann 《Developmental neurobiology》2002,53(3):343-360
The mushroom bodies (MBs), a paired structure in the insect brain, play a major role in storing and retrieving olfactory memories. We tested whether olfactory learning and odor processing is impaired in honeybees in which MB subunits were partially ablated. Using hydroxyurea (HU) to selectively kill proliferating cells, we created honeybees with varying degrees of MB lesions. Three‐dimensional reconstructions of brains were generated to analyze the drug‐induced morphological changes. These reconstructions show that, with few exceptions, only the MBs were affected by the drug, while other brain areas remained morphometrically intact. Typically, lesions affected only the MB in one hemisphere of the brain. To preclude HU‐induced physiologic deficits in the antennal lobe (AL) affecting olfactory learning, we measured the responses to odors in the AL using an in vivo calcium imaging approach. The response patterns did not differ between the AL of intact versus ablated brain sides within respective specimens. We, therefore, carried out side‐specific classical discriminative olfactory conditioning of the proboscis extension reflex (PER) with control bees and with HU‐treated bees with or without MB ablations. All experimental groups learned equally to discriminate and respond to a rewarded (CS+) but not to an unrewarded (CS?) conditioned stimulus during acquisition and retention tests. Thus, our results indicate that partial MB lesions do not affect this form of elemental olfactory learning. © 2002 Wiley Periodicals, Inc. J Neurobiol 53: 343–360, 2002 相似文献
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Andy?Pang Andrew?D?Smith Paulo?AS?Nuin Elisabeth?RM?TillierEmail author 《BMC bioinformatics》2005,6(1):236
Background
General protein evolution models help determine the baseline expectations for the evolution of sequences, and they have been extensively useful in sequence analysis and for the computer simulation of artificial sequence data sets. 相似文献245.
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Triaziflam and Diaminotriazine derivatives affect enantioselectively multiple herbicide target sites
Grossmann K Tresch S Plath P 《Zeitschrift für Naturforschung. C, Journal of biosciences》2001,56(7-8):559-569
Enantiomers of triaziflam and structurally related diaminotriazines were synthesized and their herbicidal mode of action was investigated. The compounds caused light and dark-dependent effects in multiple test systems including heterotrophic cleaver and photoautotrophic algal cell suspensions, the Hill reaction of isolated thylakoids and germinating cress seeds. Dose-response experiments revealed that the (S)-enantiomers of the compounds preferentially inhibited photosystem II electron transport (PET) and algae growth with efficacies similar to that of the herbicide atrazine. In contrast, the (R)-enantiomers of the diaminotriazines were up to 100 times more potent inhibitors of growth in cleaver cell suspensions and cress seedlings in the dark than the (S)-enantiomers. The most active compound, the (R)-enantiomer of triaziflam, inhibited shoot and root elongation of cress and maize seedlings at concentrations below 1 microM. The meristematic root tips swelled into a club shape which is typical for the action of mitotic disrupter herbicides and cellulose biosynthesis inhibitors. Microscopic examination using histochemical techniques revealed that triaziflam (R)-enantiomer blocks cell division in maize root tips 4 h after treatment. The chromosomes proceeded to a condensed state of prometaphase but were unable to progress further in the mitotic cycle. Disruption of mitosis was accompanied by a loss of spindle and phragmoplast micotubule arrays. Concomitantly, cortical microtubules decreased which could lead to isodiametric cell growth and consequently to root swelling. In addition, a decline in cellulose deposition in cell walls was found 24 h after treatment. Compared to the (R)-form, triaziflam (S)-enantiomer was clearly less active. The results suggest that triaziflam and related diaminotriazines affect enantioselectively multiple sites of action which include PET inhibitory activity, mitotic disruption by inhibiting microtubule formation and inhibition of cellulose synthesis. 相似文献
247.
Across a variety of taxa, large offspring have been demonstrated to have a fitness advantage over smaller offspring of the
same species. However, producing large offspring often comes at the cost of having to produce fewer young, and the payoff
(and thus, evolutionary outcome) of this trade-off is expected to vary between environments. Atlantic mollies (Poecilia mexicana: Poeciliidae, Teleostei), inhabiting a sulfidic cave and various non-sulfidic surface habitats in Tabasco (Mexico), are reproductively
isolated and evolved divergent female life-history traits: females of the cave ecotype produce considerably fewer, but larger
offspring. Stressful (sulfidic) environments may favor the production of larger offspring, as they are better able to cope
with chemical stressors. It remains to be determined though if increased offspring survival outweighs the fitness cost of
producing fewer but larger offspring even under benign laboratory conditions. We tested 30-day newborn survival of offspring
from wild-caught P. mexicana females from diverging populations in a low-density, no predation, no cannibalism, and ad-libitum-food, benign laboratory
environment. Survival rates were highly skewed towards larger cave molly offspring; however, surface molly females still had
a higher fitness than cave molly females in terms of higher total numbers of surviving offspring. Our study provides evidence
for an innate fitness advantage of larger cave molly offspring. Furthermore, the observed differences in life-history strategies
could promote further divergence and reproductive isolation among these ecotypes of P. mexicana, because cave molly females immigrating into the adjacent surface habitats would most likely be selected against. 相似文献
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Wuelton M Monteiro Fernando FA Val André M Siqueira Gabriel P Franca Vanderson S Sampaio Gisely C Melo Anne CG Almeida Marcelo AM Brito Henry M Peixoto Douglas Fuller Quique Bassat Gustavo AS Romero Oliveira Maria Regina F Lacerda Marcus Vinícius G 《Memórias do Instituto Oswaldo Cruz》2014,109(5):553-568