The effect of different photoperiods in circadian rhythms of per3 knockout mice.

The aim of this study was to analyse the circadian behavioural responses of mice carrying a functional knockout of the Per3 gene (Per3(-/-)) to different light : dark (L : D) cycles. Male adult wild-type (WT) and Per3(-/-) mice were kept under 12-hour light : 12-hour dark conditions (12L : 12D) and then transferred to either a short or long photoperiod and subsequently released into total darkness. All mice were exposed to both conditions, and behavioural activity data were acquired through running wheel activity and analysed for circadian characteristics during these conditions. We observed that, during the transition from 12L : 12D to 16L : 8D, Per3(-/-) mice take approximately one additional day to synchronise to the new L : D cycle compared to WT mice. Under these long photoperiod conditions, Per3(-/-) mice were more active in the light phase. Our results suggest that Per3(-/-) mice are less sensitive to light. The data presented here provides further evidence that Per3 is involved in the suppression of behavioural activity in direct response to light.

Expression profiles of voltage-gated Na(+) channel alpha-subunit genes in rat and human prostate cancer cell lines.

BACKGROUND: Voltage-gated Na(+) channel (VGSC) activity has been implicated in prostate cancer (PC) metastasis. Although VGSCs can occur as multiple-subunit assemblies, the alpha-subunits (VGSCalphas) alone can encode functional channels. The VGSCalpha gene(s) responsible for the functional VGSCalpha expression in strongly metastatic PC cell lines is not known. METHODS: Two reverse transcription-PCR (RT-PCR) methods, degenerate primer screening and a novel semi quantitative PCR (SQT-PCR) technique, were used. These methods enabled a detailed qualitative and quantitative investigation of VGSCalpha mRNA expression in rat (MAT-LyLu/AT-2) and human (PC-3/LNCaP) PC cells of markedly different metastatic potential. RESULTS: Expression of eight different VGSCalpha genes (SCN1A-4A, SCN7A-9A, and SCN11A) was determined in the PC cell lines. Most were expressed as multiple splice variants. SQT-PCR results were consistent with a basal level of VGSCalpha mRNA expression occurring in weakly metastatic (AT-2/LNCaP) cells, and this being greatly elevated in cells of stronger metastatic potential (MAT-LyLu/PC-3), primarily due to the elevated expression of the SCN9A gene (also termed PN1/hNe-Na). CONCLUSIONS: (1) Several VGSCalpha genes and their splice variants are expressed similarly in both rat and human PC cell lines. (2) Expression levels are much higher in the strongly metastatic (MAT-LyLu/PC-3) cells. (3) Levels of SCN9A mRNA specifically are predominant in MAT-LyLu and PC-3 cells; thus, SCN9A is highly likely to be the main source of the functional VGSC detected.

Dopamine receptor subtypes expressed in vertebrate (carp and eel) retinae: cloning, sequencing and comparison of five D1-like and three D2-like receptors.

Eight dopamine receptor-like cDNA clones were isolated from the carp (Cyprinus carpio) retina and four dopamine receptor-like cDNA clones were isolated from the European eel (Anguilla anguilla) retina. These cDNA clones show high sequence and structural homology to the known dopamine receptor subtypes. The sequence similarity and phylogenetic analysis revealed that five subtypes (D1A3, D1A4, D1B, D1C and D1X) in the carp retina and four subtypes (D1A1, D1A2, D1B and D1C) in the eel retina are D1-like receptor subtypes, and three (D2, D4A and D4B) in the carp retina are D2-like receptor subtypes; no D2-like receptor was found in the eel. Carp D1A3 and D1A4, carp D4A and D4B, and eel D1A1 and D1A2 are highly homologous pairs of receptors which show significant, domain-specific differences to each other and to their species homologues. The structure of the third cytoplasmic loop in the carp D1X receptor was particularly different from the other D1-like receptors. The implications of these structural differences in terms of dopamine receptor activation and signalling are discussed. It is suggested that the known diverse physiological and pharmacological effects of dopamine on the retinal neurones are likely to be mediated through these multiple receptor subtypes which may be coupled to different signal transduction pathways.

Expression of skeletal muscle-type voltage-gated Na+ channel in rat and human prostate cancer cell lines.

Previous electrophysiological work has demonstrated expression of a voltage-gated Na+ channel (VGSC) specifically in two highly metastatic prostatic epithelial tumour cell lines: MAT-LyLu (rat) and PC-3 (human). However, the identity of the channel(s) present was uncertain. The present study used a combination of molecular biological techniques to demonstrate that full-length skeletal muscle type 1 (SkM1) VGSC mRNA is present in the mRNA pool of the MAT-LyLu cell line. mRNA for this particular channel type was also expressed in the PC-3 cells. In situ hybridisation data suggested that the level and pattern of rSkM1 mRNA expression were different in the Dunning cells of markedly different metastatic potential. Interestingly, the same type of mRNA was also detected in the weakly metastatic counterparts of the cells: AT-2 (rat) and LNCaP (human).

Neurobiology of retinal dopamine in relation to degenerative states of the tissue.

Neurobiology of retinal dopamine is reviewed and discussed in relation to degenerative states of the tissue. The Introduction deals with the basic physiological actions of dopamine on the different neurons in vertebrate retinae with an emphasis upon mammals. The intimate relationship between the dopamine and melatonin systems is also covered. Recent advances in the molecular biology of dopamine receptors is reviewed in some detail. As degenerative states of the retina, three examples are highlighted: Parkinson's disease; ageing; and retinal dystrophy (retinitis pigmentosa). As visual functions controlled, at least in part, by dopamine, absolute sensitivity, spatial contrast sensitivity, temporal (including flicker) sensitivity and colour vision are reviewed. Possible cellular and synaptic bases of the visual dysfunctions observed during retinal degenerations are discussed in relation to dopaminergic control. It is concluded that impairment of the dopamine system during retinal degenerations could give rise to many of the visual abnormalities observed. In particular, the involvement of dopamine in controlling the coupling of horizontal and amacrine cell lateral systems appears to be central to the visual defects seen.

Rod opsin cDNA sequence from the sand goby (Pomatoschistus minutus) compared with those of other vertebrates.

The absorbance spectra of rods from the sand goby were measured by using microspectrophotometry. Analysis of the averaged spectra shows that the rod visual pigment has a maximum absorbance (lambda max) at approximately 501 nm. A sand goby retinal cDNA library was constructed and then screened with a partial sand goby rod opsin clone obtained by the polymerase chain reaction (PCR). The screening of the library yielded a full length rod opsin clone. The cDNA sequence and deduced amino acid sequence of this clone are compared with those of other vertebrate rod opsins.

The visual pigment basis for cone polymorphism in the guppy, Poecilia reticulata.

Long-wavelength visual pigment polymorphism, similar to that found in primates, was found in the guppy using microspectrophotometry (MSP). Guppies have a rod pigment with a wavelength of maximal absorbance (lambda max) at 501 nm and cone pigments with peak absorbance at 408 and 464 nm. In addition individuals may have one, two or three cone classes in the yellow-green region of the spectrum with mean lambda max values of 533, 543 and 572 nm. Unlike primates this variation is not sex-linked and may be based on only two visual pigments which occur either on their own in outer-segments of the 533 nm and 572 nm cone classes or as a mixture in the 543 nm cone class.

Interspecific variation in the visual pigments of deep-sea fishes.

Visual pigments in the rods of 38 species of deep-sea fish were examined by microspectrophotometry. 33 species were found to have a single rhodopsin with a wavelength of maximum absorbance (lambda max) in the range 470-495 nm. Such visual pigments have absorbance maxima close to the wavelengths of maximum spectral transmission of oceanic water. 5 species, however, did not conform to this pattern and visual pigments were found with lambda max values ranging from 451 nm to 539 nm. In 4 of these species two visual pigments were found located in two types of rod. Some 2-pigment species which have unusual red sensitivity, also have red-emitting photophores. These species have both rhodopsin and porphyropsin pigments in their retinae, which was confirmed by HPLC, and the two pigments are apparently located in separate rods in the same retinal area. In deep-sea fishes the occurrence of 'unusual' visual pigments seems to be correlated with aspects of the species' depth ranges. In addition to ecological influences we present evidence, in the form of lambda max spectral clustering, that indicates the degree of molecular constraint imposed on the evolution of visual pigments in the deep-sea.

Visual pigment polymorphism in the guppy Poecilia reticulata.

Visual pigment polymorphism similar to that found in primates is described in the photoreceptors of wild-caught guppies (Poecilia reticulata). Microspectrophotometric examination of retinal cells revealed rod visual pigments with a lambda max close to 503 nm. Classes of cones with lambda max around 410 and 465 nm were found, together with a population of pigments in the 529-579 nm range. It is in these long-wavelength cones that polymorphism occurs. Male guppies are highly polymorphic for body colour and it is possible that the cone polymorphism is related to the appreciation of the different yellow, orange and red carotenoid colour spots that are used in sexual display.