Antigenotoxic potential of rutin and quercetin in Swiss mice exposed to gamma radiation.

BACKGROUND: Ionizing radiation induces a variety of genetic damages through the formation free radicals such as reactive oxygen species (ROS). Appropriate antioxidant intervention may inhibit or reduce free radical toxicity and thus offer protection against radiation. Rutin (RUT) and quercetin (QRT) are flavonoids known to be potent dietary antioxidants. METHODS: The present study tested the antigenotoxic effect of RUT and QRT in vivo against radiation- induced chromosomal damage. Swiss albino mice were administered orally with RUT and QRT (10 and 20 mg/kg b.wt.) once daily for five consecutive days. One hour after the last administration of RUT and QRT on the fifth day, the animals were whole body exposed to 3 Gy gamma radiation. The anti-genotoxic potential was assessed in terms of chromosomal aberrations, micronucleus test, and alkaline comet assay. RESULTS: Significant decline in dicentric formation was observed in RUT and QRT treated group. Further, the antigenotoxic potential of RUT and QRT caused a significant (p < 0.001) reduction in micronucleated polychromatic, normochromatic erythrocytes; increased PCE/NCE ratio was observed in the RUT and QRT treated group. Administration of RUT and QRT before irradiation resulted in a significant (p < 0.01) decrease in the DNA damage at the post-irradiation time when compared with irradiation alone group. CONCLUSIONS: Present findings demonstrate the potential of RUT and QRT in mitigating radiation-induced mortality and cytogenetic damage, which may be attributed to scavenging of radiation-induced free radicals.

Lyriform slit sense organs on the pedipalps and spinnerets of spiders.

Lyriform slits sense organs (LSSO) are a precise assembly of stress detecting cuticular slit sensilla found on the appendages of arachnids. While these structures on the legs of the wandering spider Cupennius salei are well studied in terms of morphology, function and contribution to behaviour, their distribution on pedipalps and spinnerets of spiders is not well explored. A study was therefore carried out to observe the distribution of LSSO on pedipalps and spinnerets of some spider species. Haplogyne spiders belonging to family Pholcidae have a simple complement of LSSOs represented by one or two LSSOs on their femur. The entelegyne spiders possess a complex assembly of LSSOs on the distal segments of their pedipalps. Various types of LSSOs are found on the pedipalps indicating a capacity for analysis of complex cuticular stress. It is suggested that the complexity of LSSOs on pedipalps of entel-egyne spiders relates to courtship and spermatophore transfer and may help in reproductive isolation. Lack of LSSOs on the distal segments of pedipalps leads us to infer that unlike legs, pedipalps are less likely to receive vibratory input through their distal segments. Spinnerets have a relatively simple complement of LSSOs. One LSSO is found only on anterior spinnerets and it is a common feature observed among spiders, irrespective of the variations in web building behaviour. The orb-weaving araneid Argiope pulchella, however, has two LSSOs on the anterior spinneret. As non-web builders and orb weavers do not differ markedly in terms of LSSOs on the spinnerets and LSSOs are simple in nature (type A), it is likely that spinning and weaving are not largely regulated by sensory input from LSSOs on the spinnerets.

Golgi analysis of tangential neurons in the lobula plate of Drosophila melanogaster.

The lobula plate (LP), which is the third order optic neuropil of flies, houses wide-field neurons which are exquisitely sensitive to motion. Among Diptera, motion-sensitive neurons of larger flies have been studied at the anatomical and physiological levels. However, the neurons of Drosophila lobula plate are relatively less explored. As Drosophila permits a genetic analysis of neural functions, we have analysed the organization of lobula plate of Drosophila melanogaster. Neurons belonging to eight anatomical classes have been observed in the present study. Three neurons of the horizontal system (HS) have been visualized. The HS north (HSN) neuron, occupying the dorsal lobula plate is stunted in its geometry compared to that of larger flies. Associated with the HS neurons, thinner horizontal elements known as h-cells have also been visualized in the present study. Five of the six known neurons of the vertical system (VS) have been visualized. Three additional neurons in the proximal LP comparable in anatomy to VS system have been stained. We have termed them as additional VS (AVS)-like neurons. Three thinner tangential cells that are comparable to VS neurons, which are elements of twin vertical system (tvs); and two cells with wide dendritic fields comparable to CH neurons of Diptera have been also observed. Neurons comparable to VS cells but with 'tufted' dendrites have been stained. The HSN and VS1-VS2 neurons are dorsally stunted. This is possibly due to the shape of the compound eye of Drosophila which is reduced in the fronto-dorsal region as compared to larger flies.

Neuroarchitecture of the tritocerebrum of Drosophila melanogaster.

The organisation of the tritocerebrum of Drosophila melanogaster was studied by Bodian-Protargol reduced silver staining, Golgi-silver impregnation, horseradish peroxidase (HRP), and cobalt-chloride labelling of neurones and transmission electron microscopy. Nerve fibres of six categories were found to project to the tritocerebrum. (1 and 2) The sensory fibres from the internal mouthpart sensilla known to course along pharyngeal and accessory pharyngeal nerves were found to project in mainly two tiers, in the tritocerebrum. (3) Stomodaeal nerve fibres also project along the pharyngeal nerve, to the tritocerebrum. (4) Cells of the pars intercerebralis (PI) project along the median bundle and arborise in the tritocerebrum. HRP labelling and subsequent examination by transmission electron microscopy indicated their neurosecretory nature. (5 and 6) Two tracts of ascending fibres, designated as dorsal and ventral ascending tracts, were found to project to the tritocerebrum. Some of the sensory fibres from the labial nerve extend close to the sensory projections of the tritocerebrum, suggesting a possible convergence of the two sensory inputs. In the tritocerebrum, the sensory input, the stomodaeal input, the neurosecretory fibres of PI, and the ascending fibres were found to have overlapping fields, suggesting mutual interaction. The medial subesophageal ganglion and the tritocerebrum may interact through the ventral ascending tract.

Dopamine and nicotine, but not serotonin, modulate the crustacean ventilatory pattern generator.

Dopamine (DA) causes a dose-dependent increase in the frequency of motor neuron bursts [virtual ventilation (fR)] produced by deafferented crab ventilatory pattern generators (CPGv). Domperidone, a D2-specific DA antagonist, by itself reversibly depresses fR and also blocks the stimulatory effects of DA. Serotonin (5HT) has no direct effects on this CPGv. Nicotine also causes dramatic dose-dependent increases in the frequency of motor bursts from the CPGv. The action is triphasic, beginning with an initial reversal of burst pattern typical of reversed-mode ventilation, followed by a 2- to 3-min period of depression and then a long period of elevated burst rate. Acetylcholine chloride (ACh) alone is ineffective, but in the presence of eserine is moderately stimulatory. The inhibitory effects of nicotine are only partially blocked by curare. The excitatory action of nicotine is blocked by prior perfusion of domperidone, but not by SKF-83566.HCl, a D1-specific DA antagonist. SKF-83566 had no effects on the ongoing pattern of firing. These observations support the hypothesis that dopaminergic pathways are involved in the maintenance of the CPGv rhythm and that the acceleratory effects of nicotine may involve release of DA either directly or via stimulation of atypical ACh receptors at intraganglionic sites.