European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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Modulation of the histaminergic system and behaviour by alpha-fluoromethylhistidine in zebrafish

The functional role of histamine (HA) in zebrafish brains was studied. Zebrafish did not display a clear circadian variation in brain HA levels. Loading of zebrafish with l-histidine increased HA concentration in the brain. A single injection of the histidine decarboxylase (HDC) inhibitor, alpha-fluoromethylhistidine (alpha-FMH), gave rise to a rapid reduction in zebrafish brain HA. Low HDC activity in the brain after injections verified the effect of alpha-FMH. A reduction in the number of histaminergic fibres but not neurones and an increased expression of HDC mRNA was evident after alpha-FMH. Automated behavioural analysis after alpha-FMH injection showed no change in swimming activity, but abnormalities were detected in exploratory behaviour examined in a circular tank. No significant behavioural changes were detected after histidine loading. The time spent for performance in the T-maze was significantly increased in the first trial 4 days after alpha-FMH injections, suggesting that lack of HA may impair long-term memory. The rostrodorsal telencephalon, considered to correspond to the mammalian amygdala and hippocampus in zebrafish, is densely innervated by histaminergic fibres. These results suggest that low HA decreases anxiety and/or affects learning and memory in zebrafish, possibly through mechanisms that involve the dorsal forebrain.     

ONTOGENETIC NICHE SHIFT IN THE BRACHIOPOD TEREBRATALIA TRANSVERSA: RELATIONSHIP BETWEEN THE LOSS OF ROTATION ABILITY AND ALLOMETRIC GROWTH

Abstract: Many articulated brachiopods experience marked life habit variations during ontogeny because they experience their fluid environment at successively higher Reynolds numbers, and they can change the configuration of their inhalant and exhalant flows as body size increases. We show that the extant brachiopod Terebratalia transversa undergoes a substantial ontogenetic change in reorientation governed by rotation around the pedicle. T. transversa′s reorientation angle (maximum ability to rotate on the pedicle) decreases during ontogeny, from 180 degrees in juveniles to 10–20 degrees in individuals exceeding 5 mm, to complete cessation of rotation in individuals larger than 10 mm. Rotation ability is substantially reduced after T. transversa achieves the adult lophophore configuration and preferred orientation with respect to ambient water currents at a length of 2.5–5 mm. We hypothesize that the rotation angle of T. transversa is determined mainly by the position of ventral and dorsal points of attachment of dorsal pedicle muscles relative to the pedicle. T. transversa shows a close correlation between the ontogenetic change in reorientation angle and ontogeny of morphological traits that are related to points of attachment of dorsal pedicle muscles, although other morphological features can also limit rotation in the adult stage. The major morphological change in cardinalia shape and the observed reduction of rotation affect individuals 2.5–10 mm in length. The position of ventral insertions of dorsal pedicle muscles remains constant, but contraction of dorsal pedicle muscles is functionally handicapped because dorsal insertions shift away from the valve midline, rise above the dorsal valve floor, and become limited by a wide cardinal process early in ontogeny (<5 mm). The rate of increase of cardinal process width and of distance between dorsal pedicle muscle scars substantially decreases in the subadult stage (5–10 mm), and most of the cardinalia shell traits grow nearly isometrically in the adult stage (>10 mm). T. transversa attains smaller shell length in crevices than on exposed substrates. The proportion of small‐sized individuals and population density is lower on exposed substrates than in crevices, indicating higher juvenile mortality on substrates prone to grazing and physical disturbance. The loss of reorientation ability can be a consequence of morphological changes that strengthen substrate attachment and maximize protection against biotic or physical disturbance (1) by minimizing torques around the pedicle axis and/or (2) by shifting energy investments into attachment strength at the expense of the cost involved in reorientation.     

Progression of Parkinson's Disease Pathology Is Reproduced by Intragastric Administration of Rotenone in Mice

In patients with Parkinson''s disease (PD), the associated pathology follows a characteristic pattern involving inter alia the enteric nervous system (ENS), the dorsal motor nucleus of the vagus (DMV), the intermediolateral nucleus of the spinal cord and the substantia nigra, providing the basis for the neuropathological staging of the disease. Here we report that intragastrically administered rotenone, a commonly used pesticide that inhibits Complex I of the mitochondrial respiratory chain, is able to reproduce PD pathological staging as found in patients. Our results show that low doses of chronically and intragastrically administered rotenone induce alpha-synuclein accumulation in all the above-mentioned nervous system structures of wild-type mice. Moreover, we also observed inflammation and alpha-synuclein phosphorylation in the ENS and DMV. HPLC analysis showed no rotenone levels in the systemic blood or the central nervous system (detection limit [rotenone]<20 nM) and mitochondrial Complex I measurements showed no systemic Complex I inhibition after 1.5 months of treatment. These alterations are sequential, appearing only in synaptically connected nervous structures, treatment time-dependent and accompanied by inflammatory signs and motor dysfunctions. These results strongly suggest that the local effect of pesticides on the ENS might be sufficient to induce PD-like progression and to reproduce the neuroanatomical and neurochemical features of PD staging. It provides new insight into how environmental factors could trigger PD and suggests a transsynaptic mechanism by which PD might spread throughout the central nervous system.     

Changes in fatty acids contents and growth characteristics in transformed oilseed rape (Brassica napus)

Spring oilseed rapeBrassica napus L. ssp.oleifera cv. HM-81 was transformed with T_L-DNA of the Ri plasmid of the agropine strainAgrobacterium rhizogenes 15834. Selfed progenies (R₂ and R₃ generations) were studied for changes in values of growth characteristics and fatty acids contents. Transformants are ‘homozygous’ for T_L-DNA. Both generations of transformants differed significantly from the nontransformed control plants in reduced length, lower number of pods per plant, lower total mass of seeds and the higher number of branches. The contents of palmitic, linoleic and linolenic acids were significantly higher in transformants when compared with the control. On the contrary, the contents of both stearic and oleic acids were in most of transformants significantly lower. Only traces of erucic acid (less than 0.05 % ) were found, both in transformed and nontransformed plants.     

Neurochemical and behavioural changes in zebrafish Danio rerio after systemic administration of 6-hydroxydopamine and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

Dopaminergic deficiency in the brain of zebrafish was produced by systemic administration of two catecholaminergic neurotoxins, 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and the neurochemical and behavioural changes were characterized. The levels of dopamine and noradrenaline decreased significantly after the injection of MPTP and 6-OHDA. Corresponding to these changes, fish exhibited characteristic changes in locomotor behaviour, i.e. the total distance moved and velocity decreased after both neurotoxins. Tyrosine hydroxylase and caspase 3 protein levels were not altered after MPTP or 6-OHDA injections, as studied by immunohistochemistry and western blotting. The catecholaminergic cell clusters suggested to correspond to the mammalian nigrostriatal cell group displayed normal tyrosine hydroxylase immunoreactivity after the toxin treatment and did not show signs of DNA fragmentation that would indicate activation of cascades that lead to cell death. The results show that single systemic injections of MPTP and 6-OHDA induce both biochemical and behavioural changes in zebrafish, albeit failing to produce any significant morphological alteration in catecholaminergic cell clusters at the tested doses. This approach may be used for the screening of chemicals affecting the dopaminergic system. The model may be especially useful for evaluation of the role of novel genes in neurotoxicity, as a large number of zebrafish mutants are becoming available.     

Increased brain histamine levels in Parkinson's disease but not in multiple system atrophy

We investigated histamine concentration in post-mortem brain samples of patients with Parkinson's disease (PD, n = 24), multiple system atrophy (MSA, n = 8) and age-matched controls (n = 27). Histamine concentrations were significantly increased in the putamen (to 159% of the control mean), substantia nigra pars compacta (to 201%), internal globus pallidus (to 234%) and external globus pallidus (to 200%), i.e. in areas which play a crucial role in the motor behaviour and which show typical functional alterations in PD. In MSA no significant differences were seen. Tele-methylhistamine (histamine metabolite) concentrations were unchanged in PD. These results indicate that histamine concentration, but not its metabolism is increased in PD, but not in MSA. This finding may have implications in developing new drug therapies for PD and in differential diagnosis between PD and MSA.     

Diversity and ecology of algae from the Nahal Qishon river,northern Israel

In 59 samples of periphyton and phytoplankton collected in 2002 - 2003 from the Nahal Qishon (Qishon River), northern Israel, we found 178 species from seven divisions of algae and cyanoprocaryotes. Diatoms, clorophytes, and cyanoprocaryotes prevail. Nitzschia and Navicula (Bacillariophyta) are the most abundant. Most of the species are cosmopolitan or widespread, except Lagynion janei (Chrysophyta), which is endemic for the Mediterranean Realm. About 17% of species (26) are new for Israel and five of them represent the first recorded genera: Crinalium endophyticum Crow, Actinocyclus normanii (Gregory) Hustedt, Rhizoclonium hieroglyphicum (Agardh) Kütz (Chlorophyta), Lagynion janei Bourelly, and Stylococcus aureus Chodat. Most of them come from a rare riverine assemblage with red alga Audouinella pygmea, as well as from the estuarine assemblage. Alkaliphiles predominate among the indicators of acidity, with few acidophiles confined to the communities under the impact of industrial wastes. Among the indicators of salinity, most numerous are the oligohalobien-indifferents and species adapted to a moderate salinity level. The relative species richness of ecological groups and the indices of saprobity are correlated with changes in conductivity, pH, and N-nitrate concentration. Indicators of organic pollution fall in the range of betameso- to alfamesosaprobic self-purification grades. Our studies show ecological significance of the Nahal Qishon as a model for a strongly disturbed aquatic ecosystem in the coastal zone of eastern Mediterranean.