Population-Based Cytogenetic Banding Analysis and Phylogenetic Relationships of the Neotropical Fungus-Farming Ant Trachymyrmex holmgreni Wheeler, 1925.

Trachymyrmex is one of the most species-rich genera within fungus-farming ants and presents intraspecific cytogenetic polymorphisms as well as possible cryptic species. This ant genus is currently paraphyletic. Therefore, to unravel systematic and taxonomic misunderstandings, it is necessary to incorporate new information. We aimed to cytogenetically and genetically examine Trachymyrmex holmgreni populations from southern and northern Brazil to identify intraspecific chromosomal variations that support incipient speciation and reveal the species' position in a molecular phylogeny. Our cytogenetic approach did not show population variation in the mapping of both 18S rDNA and the TTAGG(6) motif, presenting instead a pattern characteristic of correlated species. However, the clustered pattern of the microsatellite GA(15) showed significant differences among populations: a well-defined block in each homologue, distinctly irregular signs between homologues, and blocks in 2 pairs of homologues. Our phylogenetic reconstruction yielded unexpected results, grouping representatives of 3 former morphological groups into 1 clade, namely T. urichii, T. papulatus, and T. holmgreni. Previously, it was suggested that northern and southern populations of T. holmgreni may be undergoing incipient speciation, but we can only indicate that the southernmost population differs prominently from the others in its distribution pattern of the microsatellite GA(15). Our study also supports the uniformity of karyotypes and repetitive DNA from both telomeric sequences and ribosomal DNA in Trachymyrmex studied here. In addition, we clarify some phylogenetic uncertainties within the genus and suggest further relevant systematic changes. Finally, additional studies utilizing other probes and additional populations may allow the detection of hidden genetic variation.

Cytogenetic Analysis and Chromosomal Mapping of Repetitive DNA in Melipona Species (Hymenoptera, Meliponini).

Stingless bees of the genus Melipona are subdivided into 4 subgenera called Eomelipona, Melikerria, Melipona sensu stricto, and Michmelia according to species morphology. Cytogenetically, the species of the genus Melipona show variation in the amount and distribution of heterochromatin along their chromosomes and can be separated into 2 groups: the first with low content of heterochromatin and the second with high content of heterochromatin. These heterochromatin patterns and the number of chromosomes are characteristics exclusive to Melipona karyotypes that distinguish them from the other genera of the Meliponini. To better understand the karyotype organization in Melipona and the relationship among the subgenera, we mapped repetitive sequences and analyzed previously reported cytogenetic data with the aim to identify cytogenetic markers to be used for investigating the phylogenetic relationships and chromosome evolution in the genus. In general, Melipona species have 2n = 18 chromosomes, and the species of each subgenus share the same characteristics in relation to heterochromatin regions, DAPI/CMA3 fluorophores, and the number and distribution of 18S rDNA sites. Microsatellites were observed only in euchromatin regions, whereas the (TTAGG)6 repeats were found at telomeric sites in both groups. Our data indicate that in addition to the chromosome number, the karyotypes in Melipona could be separated into 2 groups that are characterized by conserved cytogenetic features and patterns that generally are shared by species within each subgenus, which may reflect evolutionary constraints. Our results agree with the morphological separation of the Melipona into 4 subgenera, suggesting that they must be independent evolutionary lineages.

Contextual analysis and epidemiology of spider bite in southern Santa Catarina State, Brazil.

The aim of this work was to conduct an epidemiological and clinical review of 1126 cases of envenoming by spider recorded in the national notifiable diseases information system (SINAN) files of the Municipal Health Secretary of the Criciúma region, Santa Catarina State, Brazil from 1994 to 2006. This work presents a critical analysis carried out by the application of the chi(2) test, with different regional contextual parameters, including the incidence coefficient. Spider envenoming accounts for more than 50% of all cases recorded in the SINAN files for poisonous animals and is the main cause of human envenomation in the Criciúma region. The majority of the spider bites (57.4%) were reported in the hottest months, from December to May. The anatomic region that suffered the most bites was the hand. Nearly 50% of the accidents were recorded in the group aged 20-49 years. The spiders most frequently involved in accidents for all age groups were of the Loxosceles genus. Although the data collected lack further epidemiological and, especially, clinical details, this does not affect the conclusions of the study, which could be used in the planning of actions aimed at improving environmental health.

Effect of ruthenium complexes on the activities of succinate dehydrogenase and cytochrome oxidase.

In this article, we report the effects of acute administration of ruthenium complexes, trans-[RuCl(2)(nic)(4)] (nic=3-pyridinecarboxylic acid) 180.7 micromol/kg (complex I), trans-[RuCl(2)(i-nic)(4)] (i-nic=4-pyridinecarboxylic acid) 13.6 micromol/kg (complex II), trans-[RuCl(2)(dinic)(4)] (dinic=3,5-pyridinedicarboxylic acid) 180.7 micromol/kg (complex III) and trans-[RuCl(2)(i-dinic)(4)]Cl (i-dinic=3,4-pyridinedicarboxylic acid) 180.7 micromol/kg (complex IV) on succinate dehydrogenase (SDH) and cytochrome oxidase (COX) activities in brain (hippocampus, striatum and cerebral cortex), heart, skeletal muscle, liver and kidney of rats. Our results showed that complex I inhibited SDH activity in hippocampus, cerebral cortex, heart and liver; and inhibited COX in heart and kidney. Complex II inhibited SDH in heart and hippocampus; COX was inhibited in hippocampus, heart, liver and kidney. SDH activity was inhibited by complex III in heart, muscle, liver and kidney. However, COX activity was increased in hippocampus, striatum, cerebral cortex and kidney. Complex IV inhibited SDH activity in muscle and liver; COX activity was inhibited in kidney and increased in hippocampus, striatum and cerebral cortex. In a general manner, the complexes tested in this work decrease the activities of SDH and COX in heart, skeletal muscle, liver and kidney. In brain, complexes I and II were shown to be inhibitors and complexes III and IV activators of these enzymes. In vitro studies showed that the ruthenium complexes III and IV did not alter COX activity in kidney, but activated the enzyme in hippocampus, striatum and cerebral cortex, suggesting that these complexes present a direct action on COX in brain.

Modulation of creatine kinase activity by ruthenium complexes.

Creatine kinase is a crucial enzyme for brain, heart and skeletal muscle energy homeostasis, and a decrease of its activity has been associated with cell death. Many biological properties have been attributed to ruthenium complexes. In this context, this work was performed in order to evaluate creatine kinase activity from rat brain, heart and skeletal muscle (quadriceps) after administration of ruthenium complexes, trans-[RuCl(2)(nic)(4)] (nic=3-pyridinecarboxylic acid) 180.7 micromol/kg (complex I), trans-[RuCl(2)(i-nic)(4)] (i-nic=4-pyridinecarboxylic acid) 13.6 micromol/kg (complex II), trans-[RuCl(2)(dinic)(4)] (dinic=3,5-pyridinedicarboxylic acid) 180.7 micromol/kg (complex III) and trans-[RuCl(2)(i-dinic)(4)] (i-dinic=3,4-pyridinedicarboxylic acid) 180.7 micromol/kg (complex IV). Our results showed that complex I caused inhibition of creatine kinase activity in hippocampus, striatum, cerebral cortex, heart and skeletal muscle. Besides, complex II did not affect the enzyme activity. complexes III and IV increased creatine kinase activity in hippocampus, striatum, cerebral cortex and heart, but not in skeletal muscle. Besides, none of the complexes in vitro altered creatine kinase activity, suggesting that enzymatic activity is indirectly affected by complexes I, III and IV. It is believed that diminution of creatine kinase in brain of rats caused by complex I may be related to results from other study reporting memory impairment caused by the same complex. Further research is necessary in order to elucidate the effects of ruthenium complexes in other important metabolic enzymes.