Cognitive disturbances in the cuprizone model of multiple sclerosis

Cognitive problems frequently accompany neurological manifestations of multiple sclerosis (MS). However, during screening of preclinical candidates, assessments of behaviour in mouse models of MS typically focus on locomotor activity. In the present study, we analysed cognitive behaviour of 9 to 10-week-old female C57Bl/6J mice orally administered with the toxin cuprizone that induces demyelination, a characteristic feature of MS. Animals received 400 mg/kg cuprizone daily for 2 or 4 weeks, and their performance was compared with that of vehicle-treated mice. Cuprizone-treated animals showed multiple deficits in short touchscreen-based operant tasks: they responded more slowly to visual stimuli, rewards and made more errors in a simple rule-learning task. In contextual/cued fear conditioning experiments, cuprizone-treated mice showed significantly lower levels of contextual freezing than vehicle-treated mice. Diffusion tensor imaging showed treatment-dependent changes in fractional anisotropy as well as in axial and mean diffusivities in different white matter areas. Lower values of fractional anisotropy and axial diffusivity in cuprizone-treated mice indicated developing demyelination and/or axonal damage. Several diffusion tensor imaging measurements correlated with learning parameters. Our results show that translational touchscreen operant tests and fear conditioning paradigms can reliably detect cognitive consequences of cuprizone treatment. The suggested experimental approach enables screening novel MS drug candidates in longitudinal experiments for their ability to improve pathological changes in brain structure and reverse cognitive deficits.     

Genetic variation of the Siberian tit Parus cinctus populations at the regional level: a mitochondrial sequence analysis

We studied the matrilinear genetic structure of the Siberian tit Parus cinctus by sequencing 911 bp of the mitochondrial control region of 56 birds from Fennoscandia and 3 from Yakutia, central Siberia, representing subspecies P. c. lapponicus and P. c. cinctus , respectively. One major haplotype comprised 35.7% of all birds and was present in all Fennoscandian populations. Sequence variation of 5 museum specimens from Norway fitted with the pattern of the present-day birds. The nucleotide diversity was 0.00205±0.00025 in the Fennoscandian population and no population structuring was detected. The star-like phylogeny suggests a recent expansion of the population size in the evolutionary time scale. A modern decline of the population size from 200 000 pairs to 50 000 pairs in Finland has resulted from cutting and fragmentation of old-growth forests, but the effects of this could not yet be detected in the mtDNA pattern. However, the nucleotide diversity differed among populations being the highest at Kuusamo, close to the Russian border. Conceivably, the gene flow maintained by the substantial migration of Siberian tits is sufficient to prevent differentiation of local populations in Fennoscandia. Presumably the large conservation areas in NE Finland and on the Russian side of the border contribute to the high genetic variation observed in the Kuusamo population. Comparison of the mtDNA phylogeny of the Siberian tit with the phylogenies of the great tit, the blue tit and the willow tit showed that the Siberian tit and some other non-migratory species of the foliage gleaning guild share similar post glacial histories in the western palaearctic.     

Histochemical demonstration of carbonic anhydrase activity in the uterus

Summary Positive histochemioal reaction for carbonic anhydrase (CAH) activity was observed in the glandular and lining epithelium of human and rat uteri. The CAH activity in the rat endometrium showed cyclic changes during the estrous cycle. Only one main component of CAH activity was revealed by electrophoresis, under conditions when the erythrocytes showed several isozymes.     

The effects of UV-B radiation on epidermal anatomy in loblolly pine (Pinus taeda L.) and Scots pine (Pinus sylvestris L.)

The effects of enhanced UV‐B radiation on the needle anatomy of loblolly pine (Pinus taeda L.) and Scots pine (Pinus sylvestris L.) were studied in the field under supplemental UV‐B radiation supplied by a modulated irradiation system. The supplemental UV‐B levels were designed to simulate either a 16 or 25% loss of stratospheric ozone over College Park, Maryland. Enhanced UV‐B radiation caused different responses in these two species. The needles of loblolly pine had larger amounts of tannin in the lumen of epidermal cells and more wall‐bound phenolics in the outer epidermal walls of UV‐B‐treated needles, whereas the most pronounced effect on Scots pine needles was increased cutinization. In both species, the outer epidermal cell walls thickened and the needle cross‐sectional and mesophyll areas decreased (statistically significantly only in Scots pine). This suggests that more carbon may have been allocated to the protection mechanisms at the expense of photosynthetic area. The difference in response between these species suggests that the response to UV‐B radiation is not mediated by a single mechanism and that no generalization with regard to the effects of UV‐B on conifers can be made.     

Comparison of methods used in zooplankton sampling and counting in the joint Russian-Finnish evaluation of the trophic state of Lake Ladoga

The results of a joint Russian-Finnish investigation on zooplankton in Lake Ladoga are presented, and a comparison is made between two sampling techniques, tube sampler and plankton net, and between two counting methods. The precision of subsampling and sampling is further discussed on the basis of zooplankton data gathered in Lake Saimaa, Finland. The comparison clearly indicates that a tube sampler is required for reliable sampling of small-sized animals, while a plankton net saves time and is a more economical sampler for large, rare or active animals. The comparison between the results obtained by Finnish and Russian workers, using different counting procedures, shows that the main groups of crustacean zooplankton are similarly counted and identified in the two laboratories.     

Spectral properties of light affect plasma and pituitary gonadotropins in male rats

In order to find out whether different light spectra have any role in regulating the gonadotropin levels in male rats, we compared the 24-hour patterns of plasma and pituitary gonadotropins in rats kept for 7 days in natural or in cool white artificial lighting (exp. I). The intensity and periodicity of the two lighting conditions were adjusted as similar as possible. Further, we measured plasma and pituitary gonadotropins in the middle of the light period and in the middle of the dark period in rats kept for 7 days under artificial lightings of three different spectra (exp. II). In both experiments, in all lighting conditions we found higher plasma levels of LH and FSH during the dark than the light period. The differences were statistically significant only when the illumination contained more long and/or short wavelengths than the usual cool white laboratory lighting. The pituitary contents of gonadotropins were not found to vary with the periodicity of lighting. In the 24-hour patterns the overall plasma levels were higher and the pituitary contents of gonadotropins lower in natural lighting than in cool white lighting. It was concluded that the spectral properties of light influence the secretion of gonadotropins in male rats, but the mechanism involved remains to be clarified.