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Neutral and cationic cyclopentadienone (CpO) N-heterocyclic carbene (NHC) bis-carbonyl iron(0) complexes bearing, appended to the NHC ligand, either a terminal amino group on the lateral chain, [Fe(η 4 -CpO)(CO) 2 (κC-NHC(CH 2 ) n NH 2 )] with n=2 (2a) and 3 (2b), or a cationic NMe 3+ fragment, [Fe(η 4 -CpO)(CO) 2 (κC-NHC(CH 2 ) 2 NMe 3 )](I) (3), were prepared and characterized in terms of their structure, stability and reactivity. The photochemical properties of 2a and 2b were examined both in organic solvents and in water, revealing the photoactivated release of one CO ligand followed by the formation of the chelated complex [Fe(η 4 -CpO)(CO)(κ 2 C,N-NHC(CH 2 ) 2 NH 2 )] (4), whose molecular structure was confirmed by single crystal X-ray diffraction studies. This metallacyclization occurs only in the case of 2a, with the ethylene spacer between NHC ring and NH 2 group in the lateral chain, allowing the formation of a stable 6-membered ring. On the other hand, 2b undergoes decomposition upon irradiation. The reactivity in aqueous solutions revealed the chemical speciation of the complexes at different pH and especially under physiological conditions (phosphate buffer solution at pH7.4 and 37°C). The lack of data on the biological properties of iron(0) complexes prompted us to preliminarily investigate their cytotoxicity against model cancer cells (AsPC-1 and HPAF-II), along with a determination of their lipophilicity.

The head morphology and feeding habits of pairs of characin species (family Characidae) that coexist in four different coastal rainforest streams were analysed. Coexisting species differed in size, but were very similar in eco‐morphological attributes. Gut analyses revealed differences in feeding preferences for each coexisting species, indicating resource partitioning. A pattern of organization in species pairs that was repeated in the four studied streams was noticed. The pattern consisted of one slightly larger species with a feeding preference for items of allochthonous origin and another smaller species with a preference for autochthonous items. The hypothesis that small morphological differences enable the current coexistence of those species pairs was proposed. Furthermore, the results show ecological equivalence among different species in the studied streams., This study was supported financially by the Brazilian agencies CAPES, CNPQ, FAPERJand UERJ, through grants FAPERJ E/26-170.578/2006, no. E/26-110.920/2013, CNPq no.300481/2010-0 and Prociência – UERJ to R.M., FAPERJ E-26/103.016/2011, CNPq no.307715/2009-4 and Prociência – UERJ to H.G.B., PIBIC UERJ to T.P. and CAPES to L.R.M.Warm thanks are due to the staff and students of the Department of Ecology at UERJ (RJ,Brazil) for field and laboratory assistance.

The effects of riparian forest removal on a neotropical stream fish assemblage were assessed in the MataAtlântica.Fishassemblagestructureandfishfeedingpatternswerequantifiedatthreesitesalong a pristine-to-deforested gradient in a Serra do Mar stream: (1) a pristine site fully covered by canopy with no light penetration and transparent waters, (2) an intermediate site with partially removed forest and (3) a fully removed forest site with no canopy and full light penetration where siltation and turbid waterspredominate.Fishassemblagestructure,fishdensitiesandtheirfeedingpatternsdifferedwidely among sites. Whilst the same five fish species occurred at the three sites, forest removal favoured the occurrence of sediment-tolerant iliophagous benthic species at the deforested site. At the pristine site, invertebrate prey predominated in water column fish diet and feeding overlap among species was low. Severe shifts in the feeding patterns were noticed in both deforested sites. Invertebrates were replaced by detritus, organic matter and algae at both sites and feeding overlap increased markedly. The overwhelmingfeedingadaptabilityoftheseneotropicalfishesappearedcapableofbufferingthedeleterious effects of forest removal on stream quality in terms of increased light penetration, siltation and water turbidity. Forest cutting in this Mata Atlântica stream clearly caused strong functional changes associated with forest clearance through important modifications in the assemblageorganizationandtrophic patterns of the main species, but did not eliminate species.

Spatio-temporal changes in the diet, niche breadth and niche overlap of two species of Characidium from three different sites along a Neotropical coastal stream were studied during a dry and rainy season. Seasonal changes were restricted to the occurrence of plant items in the stomach contents. The relative importance of food items in the diet of both species varied across sites, but Diptera, Ephemeroptera, Simuliidae, Trichoptera and Coleoptera larvae were always the main prey items. Contrary to the expected pattern, values of the niche breadth were higher at the site where Characidium species co-existed and niche overlapped at this site indicated 52% (p = 0.52) of feeding overlap.

Spatio-temporal changes in the diet, niche breadth and niche overlap of two species of Characidium from three different sites along a Neotropical coastal stream were studied during a dry and rainy season. Seasonal changes were restricted to the occurrence of plant items in the stomach contents. The relative importance of food items in the diet of both species varied across sites, but Diptera, Ephemeroptera, Simuliidae, Trichoptera and Coleoptera larvae were always the main prey items. Contrary to the expected pattern, values of the niche breadth were higher at the site where Characidium species co-existed and niche overlapped at this site indicated 52% (p = 0.52) of feeding overlap. Variações espaço-temporal na dieta, na amplitude e na sobreposição de nicho foram estudadas para duas espécies de Characidium de três localidades distintas de um riacho costeiro da região Neotropical, considerando-se as estações seca e chuvosa. As alterações sazonais na dieta foram restritas à presença/ausência de itens vegetais nos conteúdos estomacais. A importância relativa dos itens alimentares, de ambas as espécies, variou entre as localidades de estudo; porém, as larvas de Diptera, Ephemeroptera, Simuliidae, Trichoptera e Coleoptera foram sempre as presas mais consumidas. Em oposição ao padrão esperado, os valores de amplitude de nicho foram maiores na localidade em que as duas espécies de Characidium ocorreram em sintopia e a sobreposição de nicho, nessa localidade, indicou 52% (p = 0,52) de sobreposição alimentar.

In the present study we aimed to compare the feeding ecology of Hypostomus punctatus from a coastal stream from Southeast Brazil with data previously published for the same study site before environmental changes. Feeding preferences were assessed through a sample of 138 specimens (67 from the dry and 71 from the rainy season) using the Index of Alimentary Importance (IAi). We registered five different food items (detritus, plant fragments, Diatoms, Chloroficeae and Cianobacteries) composing the species diet. Detritus was the most abundant one both during the rainy and dry seasons (IAirainny = 90.34 and IAidry = 96.30). No significant differences were registered for the volume of food items consumed during the rainy and dry seasons. The Frequency of Occurrence analysis showed that four (detritus, plant fragments, Diatoms and Chloroficeae) among the five all other consumed ones, were always frequent. Comparing our own results with those available for the study site, we suggest that the feeding habit of H. punctatus has changed according to environmental changes and that the species diet is strongly dependent upon environmental conditions. No presente estudo, tivemos como objetivo comparar a ecologia trófica de Hypostomus punctatus de um riacho costeiro do sudeste do Brasil com dados previamente publicados para a mesma localidade deste estudo, antes que tenha sofrido alterações ambientais. As preferências alimentares foram analisadas através da análise de 138 exemplares (67 da estação seca e 71 da estação chuvosa), utilizando-se o Índice de Importância Alimentar (IAi). Registramos cinco diferentes itens alimentares (detrito, fragmentos vegetais, Diatomáceas, Clorofíceas e Cianobactérias), compondo a dieta da espécie. Detrito foi o item mais abundante, tanto durante a estação chuvosa como durante a seca (IAichuva = 90,34 e IAiseca = 96,30). Não foram registradas diferenças significativas entre o volume consumido de cada um dos itens na estação seca e chuvosa. A análise da frequência de ocorrência mostrou que quatro (detrito, fragmento vegetal, Diatomáceas e Clorofíceas) entre os cinco itens consumidos foram sempre frequentes. Comparando nossos resultados com aqueles previamente publicados, sugerimos que o hábito alimentar de H. punctatus mudou de acordo com as alterações ambientais e que sua dieta é fortemente dependente das condições ambientais.

In the present study we aimed to compare the feeding ecology of Hypostomus punctatus from a coastal stream from Southeast Brazil with data previously published for the same study site before environmental changes. Feeding preferences were assessed through a sample of 138 specimens (67 from the dry and 71 from the rainy season) using the Index of Alimentary Importance (IAi). We registered five different food items (detritus, plant fragments, Diatoms, Chloroficeae and Cianobacteries) composing the species diet. Detritus was the most abundant one both during the rainy and dry seasons (IAirainny = 90.34 and IAidry = 96.30). No significant differences were registered for the volume of food items consumed during the rainy and dry seasons. The Frequency of Occurrence analysis showed that four (detritus, plant fragments, Diatoms and Chloroficeae) among the five all other consumed ones, were always frequent. Comparing our own results with those available for the study site, we suggest that the feeding habit of H. punctatus has changed according to environmental changes and that the species diet is strongly dependent upon environmental conditions.

The present study was conducted at the Córrego Andorinha on the eastern slope of Ilha Grande and aimed to determine the alimentary daily rhythm of Bryconamericus microcephalus. Fishes were sampled at a 4 hours interval over a 24 hours period during winter 2002 and summer 2003. Gut fullness was determined according to a numerical scale ranging from 0 (empty gut) to 3 (full gut). No differences were registered for the daily ration estimates between seasons. It is concluded that B. microcephalus is a diurnal feeding species, as the high values of gut fullness occurred between 11:00 AM and 3:00 PM. O presente estudo foi desenvolvido no Córrego Andorinha, localizado na vertente continental da Ilha Grande e teve como objetivo avaliar o ritmo diário da alimentação de Bryconamericus microcephalus. Os peixes foram amostrados ao longo de 24 horas a intervalos de 4 horas, no inverno de 2002 e no verão de 2003. O grau de repleção estomacal foi determinado de acordo com uma escala numérica que variou de 0 (estômago vazio) a 3 (estômago cheio). Não foram registradas diferenças para o ritmo diário de alimentação, quando consideradas as duas estações estudadas. Concluímos que B. microcephalus tem hábito alimentar diurno com os maiores valores de graus de repleção entre 11:00 e 15:00 horas.

The objective of this study was to compare the safety, tolerability and clinical response of once- versus twice-daily administration of didanosine given at a dosage of 270 mg/m2/day in children with symptomatic HIV-associated disease who were intolerant to or clinically deteriorated on zidovudine monotherapy. We carried out a randomized, open-label multicentre trial. Didanosine was supplied in buffered tablets, which could be chewed or dispersed in liquid. The children were recruited from 16 paediatric departments participating in the Italian Register for HIV Infection in Children. A total of 53 children (median age 5.5 years) started trial treatment; 26 were given didanosine twice daily and 27 once daily; 85% had AIDS and 98% had clinically deteriorated while on zidovudine therapy. Similar safety and tolerability results were demonstrated for the two schemes of therapy. A total of 11 children (20.7%) required discontinuation of didanosine for severe adverse events (five children (19.2%) in the twice-daily group; six children (22.2%) in the once-daily group, log-rank P = 0.81). Severe hepatic toxicity was uncommon (5.6%) while mild to moderate hepatic dysfunction was demonstrated in about 17% of the participants, without any difference between the two groups. Haematological toxicity was common (about 40% of the children, 11 in the twice- and 19 in the once-daily group) but never severe. Clinical pancreatitis and retinal lesions were never demonstrated. There was no significant difference in progression to death or to a new opportunistic infection between the two treatment regimens (log-rank P = 0.54). The modification of surrogate efficacy parameters during the study period was similar in the two groups. However, weight gain was poorer in children treated once daily. This study suggests that the safety and tolerability of 270 mg/m2/day of didanosine given once daily is substantially similar to that of the traditionally recommended schedule of two divided doses. Owing to the small sample and to the severity of the clinical condition of the children enrolled, no definite conclusions on the comparative efficacy of the two regimens can be drawn.

Aspects of the reproductive biology of Astyanax janeiroensis in the Ubatiba river in Maricá, RJ, Brazil were evaluated in order to ascertain whether the strategy adopted by the species is causally related to environmental variables. Specimens were collected on a monthly basis from October 1994 to September 1995, through electrofishing. The Sex ratio was not significantly different from the expected frequency of 1:1 (G = 1.29; p > 0.50); nonetheless, considering three standard length classes, significantly larger numbers of females were recorded for the higher SL class (G = 11.07; p < 0.01). Size at first maturation showed no significant differences between sexes. Length-weight ratio analyses showed negative allometry for males and isometry, for females. Length structure was significantly different between sexes, suggesting that females are larger than males (D = 0.027, p < 0.01). Reproductive specimens were recorded during nine months of the annual cycle. Seasonal variations of reproductive specimens belonging to two different standard length classes displayed an asynchronous behavior, with larger specimens having a longer reproductive period and smaller ones reproducing for fewer months during the annual cycle. High values of fecundity (F), varying from 3169 to 18714 oocytes, were recorded for fish of 9.1 and 10.2 cm lengths, respectively. The correlation between weight and number of oocytes/unit of weight was positive, indicating that larger specimens produced more eggs. Foram analisados aspectos da biologia reprodutiva de Astyanax janeiroensis do rio Ubatiba - Maricá, RJ, afim de discutir se a estratégia adotada possui alguma relação de causalidade com as variáveis ambientais. Os espécimens foram coletados mensalmente, entre outubro 1994 e setembro 1995, mediante pesca elétrica. A proporção sexual não diferiu significativamente do esperado 1:1 (G = 1.29; p > 0.50); mas, considerando-se 3 classes de tamanho distintas, foi registrada diferença significativa, com predomínio de fêmeas, na classe de maior tamanho (G = 11,07; p < 0,01). O tamanho médio da 1ª maturação não apresentou diferença significativa entre os sexos. A análise da relação entre o peso e o indicou alometria negativa para os machos e isometria para as fêmeas. A estrutura de tamanho foi significativamente diferente entre os sexos sugerindo que as fêmeas alcançam tamanho superior ao dos machos (D = 0,027, p < 0,01). Foram registrados indivíduos reprodutivos ao longo de nove meses do ciclo anual. A variação temporal de indivíduos reprodutivos, de duas classes de comprimento, indicou comportamento assincrônico com os exemplares de maior tamanho reproduzindo durante um maior intervalo de tempo e os exemplares menores com reprodução restrita a alguns meses do ciclo anual. Altos valores de fecundidade foram registrados, variando de 3169 a 18714 ovócitos para peixes de 9,1 a 10,2 cm, respectivamente. Análises de correlação, entre peso total e o número de ovócitos/unidade de peso, apresentou correlação positiva e indicou que os espécimes maiores produzem mais ovos.