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31.
Dheeraj?K.?Veeranagoudar Bhagyashri?A.?Shanbhag Srinivas?K.?SaidapurEmail author 《Acta ethologica》2004,7(1):37-41
Mechanism of food detection in Rana temporalis tadpoles was studied using a rectangular choice tank with end compartments (stimulus zones) providing exclusively visual and/or chemical food cues. Boiled spinach served as the food. The test tadpoles were starved for 24 h before use. They were released from the center of the choice tank (n=24) after 5 min of acclimation to test for end bias and food-detecting mechanism. The number of tadpoles in the two stimulus zones was recorded at 5-min intervals from 10 to 30 min. In the end-bias tests (without food cues) tadpole distribution was comparable at all times in the two compartments of the choice tank, exhibiting no end bias. In tests with the visual food cues provided in one of the stimulus zones, the tadpole distribution was also random. On the other hand, in experiments involving chemical cues emanating from food the tadpoles preferentially associated with the food source in significantly greater numbers compared to the zone lacking food or providing only a visual cue. The experiments with individual test tadpoles also revealed that they detect food based on chemical cues and ruled out copycat behavior. These findings on R. temporalis tadpoles reveal that chemical senses predominate over the visual senses in detection of food and foraging. 相似文献
32.
Verheule S Wilson E Banthia S Everett TH Shanbhag S Sih HJ Olgin J 《American journal of physiology. Heart and circulatory physiology》2004,287(2):H634-H644
Chronic rapid atrial pacing (RAP) leads to changes that perpetuate atrial fibrillation (AF). Chronic atrial dilatation due to mitral regurgitation (MR) also increases AF inducibility, but it is not clear whether the underlying mechanism is similar. Therefore, we have investigated atrial electrophysiology in a canine MR model (mitral valve avulsion, 1 mo) using high-resolution optical mapping and compared it with control dogs and with the canine RAP model (6-8 wk of atrial pacing at 600 beats/min, atrioventricular block, and ventricular pacing at 100 beats/min). At followup, optical action potentials were recorded using a 16 x 16 photodiode array from 2 x 2-cm left atrial (LA) and right atrial (RA) areas in perfused preparations, with pacing electrodes around the field of view to study direction dependency of conduction. Action potential duration at 80% repolarization (APD(80)) was not different between control and MR but was reduced in RAP atria. Conduction velocities during normal pacing were not different between groups. However, the MR LA showed increased conduction heterogeneity during pacing at short cycle lengths and during premature extrastimuli, which frequently caused pronounced regional conduction slowing. Conduction in the MR LA during extrastimulation also displayed a marked dependence on propagation direction. These phenomena were not observed in the MR RA and in control and RAP atria. Thus both models form distinctly different AF substrates; in RAP dogs, the decrease in APD(80) may stabilize reentry. In MR dogs, regional LA conduction slowing and increased directional dependency, allowing unidirectional conduction block and preferential paths of conduction, may account for increased AF inducibility. 相似文献
33.
Summary Earlier studies using Golgi silver impregnations from the labellar sensilla of adult Drosophila melanogaster revealed seven types of sensory axons projecting into the suboesophageal ganglion of the brain. These sensory terminals were designated as coiled fibres (type-I), shrubby fibres (type-II), ipsilateral ventral fibres (type-III), ipsilateral dorsal fibres (type-IV), contralateral ventral fibres (type-V), contralateral dorsal fibres (type-VI), and central fibres (type-VII). The present study identifies the projections of sensory neurons present in a single labellar taste-sensillum, using the neuronal marker horseradish peroxidase (HRP). Although the taste sensillum in question has five neurons, in a given experiment only one or at the most two neurons are labelled. The type of neuron labelled was usually specific to the stimulant solute (sucrose, sodium chloride or potassium chloride) present in the HRP solution. Although type-II fibres get labelled most of the time, irrespective of the stimulant present in HRP solution, type-IV fibres are labelled when attractants (0.1 M sucrose or 0.1 M sodium chloride) are used as stimulants in HRP solution. Type-VI fibres are labelled when the stimulant is 0.1 M potassium chloride, a repellent. HRP dissolved in distilled water revealed type-I coiled fibres. Besides revealing projections of sensillar neurons to the brain the present technique also inferred their possible function. Incubation of whole-brain tissue with 0.04% 3,3-diaminobenzidine tetrahydrochloride in presence of 0.06% hydrogen peroxide suggested that the glomerular organization is also present in the taste-sensory region as it is in olfactory neuropile. 相似文献
34.
35.
Jaiswal A Parihar VK Sudheer Kumar M Manjula SD Krishnanand BR Shanbhag R Unnikrishnan MK 《Mutation research》2005,585(1-2):50-59
Pre-treatment with 5-aminosalicylic acid (5-ASA) significantly reduced sperm-shape abnormalities in endosulfan-treated rats. The number of abnormal sperm in the epididymis was markedly increased by endosulfan treatment but pre-treatment with 5-ASA kept these values close to normal. Treatment with 5-ASA at a dose of 25 mg/kg bw was more effective in reducing sperm-shape abnormality and sperm count than at a dose of 50 mg/kg bw. Endosulfan significantly increased the level of lactate dehydrogenase (LDH) in rats but a marked decrease was observed upon pre-treatment with 25 mg/kg bw 5-ASA. Changes in plasma testosterone levels were not significantly correlated with 5-ASA pre-treatment but histopathological analysis of seminiferous tubules and Leydig cells showed significant protection from endosulfan-induced tissue damage such as necrosis. The population of Sertoli cells increased and the lumen of the seminiferous tubules contained a greater number of spermatids. There was a corresponding increase in the number of Leydig cells. A curative study with 5-ASA showed a similar protection from endosulfan-induced toxicity and cellular damage, but the extent of protection was significantly lower. 相似文献
36.
Park SK Shanbhag SR Dubin AE de Bruyne M Wang Q Yu P Shimoni N D'Mello S Carlson JR Harris GL Steinbrecht RA Pikielny CW 《Journal of neurobiology》2002,51(3):248-260
The olfactory organs on the head of Drosophila, antennae and maxillary palps, contain several hundred olfactory hairs, each with one or more olfactory receptor neurons. Olfactory hairs belong to one of three main morphological types, trichoid, basiconic, and coeloconic sensilla, and show characteristic spatial distribution patterns on the surface of the antenna and maxillary palps. Here we show that targeting expression of the cell-death gene reaper to basiconic sensilla (BS) causes the specific inactivation of most olfactory sensilla of this type with no detectable effect on other types of olfactory sensilla or the structure of the antennal lobe. Our data suggest that BS are required for a normal sensitivity to many odorants with a variety of chemical structures, through a wide range of concentrations. Interestingly, however, in contrast to other odorants tested, the behavioral response of ablated flies to intermediate concentrations of propionic and butyric acids is normal, suggesting the involvement of sensilla unaffected by ectopic reaper expression, probably coeloconic sensilla that respond strongly to these two organic acids. As inactivation of BS causes an underestimation of the concentration of both acids detectable at both the highest and lowest odorants concentrations, our results suggest that concentration coding for these two odorants relies on the integration of signals from different subsets of sensilla, most likely of different morphological types. 相似文献
37.
Rebecca Lopez Arunkumar Arumugam Riya Joseph Kanika Monga Thiyagarajan Boopalan Pamela Agullo Christina Gutierrez Sushmita Nandy Ramadevi Subramani Jose Manuel de la Rosa Rajkumar Lakshmanaswamy 《PloS one》2013,8(11)
Obesity and diabetes are associated with increased breast cancer risk and worse disease progression once cancer is diagnosed; however, the exact etiology behind these observations remains to be fully elucidated. Due to the global obesity/diabetes pandemic, it is imperative to understand how these diseases promote and enhance breast cancer and other common cancers. In this study we demonstrate that hyperglycemia promotes breast cancer by altering leptin/IGF1R and AKT/mTOR signaling. To our knowledge, we show for the first time that in breast epithelial cells, hyperglycemia alone directly impacts leptin signaling. Hyperglycemia increased proliferation of both non-tumorigenic and malignant mammary epithelial cells. These observations coincided with increased leptin receptor and IGF1R receptor, as well as, increased levels of GRB2, pJAK2, pSTAT3, pIRS1/2, pAKT, and p-mTOR. Moreover, pJAK2 was almost completely colocalized with leptin receptor under high glucose conditions. These results demonstrate how hyperglycemia can potentially increase the risk of breast cancer in premalignant lesions and enhance cancer progression in malignant cells. 相似文献
38.
Sheng Zhou Sho SugawaraShohei Riya Masaki SagehashiKoki Toyota Akihiko TeradaMasaaki Hosomi 《Ecological Engineering》2011,37(5):685-692
Flooded paddy fields perform many ecological and conservation functions and are also reported to facilitate livestock waste disposal. Paddy field infiltration rates are important for nitrogen dynamics. A laboratory study was conducted to compare the effects of infiltration rate on nitrogen dynamics including nitrogen leaching, soil adsorption, microorganism assimilation, plant uptake and denitrification. Two infiltration rates were applied to paddy soil: 18.6 ± 10.3 mm d−1 (High Infiltration Columns: HIC) and 4.49 ± 3.15 mm d−1 (Low Infiltration Columns: LIC). Total nitrogen load was 484 kg-N ha−1, with the ammonium ion form including basal fertilizer and a double supplemental fertilizer application. A (15NH4)2SO4 tracer was applied in each infiltration rate as supplemental fertilizer.Nitrification and denitrification, plant uptake, soil adsorption, and leaching differed between infiltration rates. Compared with high nitrate concentration in HIC soil water, little nitrate appeared in the LIC, and it maintained relatively higher soil water ammonium concentrations long after application. The 15N assimilated by rice and contained in the LIC soil was higher than in the HIC, suggesting that low infiltration is beneficial to nitrogen assimilation, adsorption and fixation. Although loss of nitrogen via leaching was higher in the HIC than the LIC, it accounted for only 3.94% of total 15N input. About 69.4% of total 15N input was unaccounted for in the HIC, whereas 38.3% of total 15N input was unaccounted for in the LIC. According to the denitrification rate calculated from changes in 29N2/28N2 and 30N2/28N2 ratios, the denitrification rate after HIC application was higher than the LIC, reaching a maximum rate of 2.9 g m−2 d−1. This suggests that high infiltration rate enhances nitrification and denitrification, with most of the unaccounted inputted 15N in the HIC was probably lost through nitrification and denitrification. 相似文献
39.
Absence of kin discrimination in cannibalistic Anuran tadpoles of the frog Hoplobatrachus tigerinus (Daudin) 总被引:1,自引:0,他引:1
Kin discrimination was tested in the cannibalistic H. tigerinus tadpoles to know whether cannibalism is selectively directed towards non-kin members or it is indiscriminate. The association choice tests were conducted using satiated as well as starved subjects with the assumption that they will associate near non-sibs rather than near sibs with the intention of preferentially cannibalizing them. However, test tadpoles, fed or starved showed a random association choice with sibs and non-sibs, as in the end-bias stimulus blank tests. Therefore it is suggested that cannibalistic H. tigerinus tadpoles do not discriminate sibs from non-sibs and cannibalize on both rather indiscriminately. 相似文献
40.
Bipin P. Kulkarni Sona B. Nair Manasi Vijapurkar Leenam Mota Sharda Shanbhag Shehnaz Ali Shrimati D. Shetty Kanjaksha Ghosh 《PloS one》2014,9(10)