Chromosomal evolution in Cryptangieae Benth. (Cyperaceae): Evidence of holocentrism and pseudomonads.

Cryptangieae has recently been revised based on morphology and molecular phylogeny, but cytogenetic data is still scarce. We conducted this study with the aim of investigating the occurrence of holocentric chromosomes and pseudomonads, as well as understanding the mode of chromosomal evolution in the tribe. We performed analyses of meiotic behavior, chromosome counts, and reconstruction of the ancestral state for the haploid number. We present novel cytogenetic data for eight potentially holocentric species: Cryptangium verticillatum, Krenakia junciforme, K. minarum, Lagenocarpus bracteosus, L. griseus, L. inversus, L. rigidus, and L. tenuifolius. Meiotic abnormalities were observed, with parallel spindles being particularly noteworthy. Intra-specific variations in chromosome number were not found, which may indicate an efficient genetic control for the elimination of abnormal nuclei. The inferred ancestral haploid number was n = 16, with dysploidy being the main evolutionary mechanism. At least five chromosomal fissions occurred in Krenakia (n = 21), followed by a further ascending dysploidy event in Lagenocarpus (n = 17). As proposed for Cyperaceae, it is possible that cladogenesis events in Cryptangieae were marked by numerical and structural chromosomal changes.

Both male and female meiosis contribute to non-Mendelian inheritance of parental chromosomes in interspecific plant hybrids (Lolium × Festuca).

Some interspecific plant hybrids show unequal transmission of chromosomes from parental genomes to the successive generations. It has been suggested that this is due to a differential behavior of parental chromosomes during meiosis. However, underlying mechanism is unknown. We analyzed chromosome composition of the F2 generation of Festuca × Lolium hybrids and reciprocal backcrosses to elucidate effects of male and female meiosis on the shift in parental genome composition. We studied male meiosis, including the attachment of chromosomes to the karyokinetic spindle and gene expression profiling of the kinetochore genes. We found that Lolium and Festuca homoeologues were transmitted differently to the F2 generation. Female meiosis led to the replacement of Festuca chromosomes by their Lolium counterparts. In male meiosis, Festuca univalents were attached less frequently to microtubules than Lolium univalents, lagged in divisions and formed micronuclei, which were subsequently eliminated. Genome sequence analysis revealed a number of non-synonymous mutations between copies of the kinetochore genes from Festuca and Lolium genomes. Furthermore, we found that outer kinetochore proteins NDC80 and NNF1 were exclusively expressed from the Lolium allele. We hypothesize that silencing of Festuca alleles results in improper attachment of Festuca chromosomes to karyokinetic spindle and subsequently their gradual elimination.

Genomic constitution, allopolyploidy, and evolutionary proposal for Cynodon Rich. based on GISH.

Polyploidy is the main mechanism for chromosome number variation in Cynodon. Taxonomic boundaries are difficult to define and, although phylogenetic studies indicate that some species are closely related, the degree of genomic similarity remains unknown. Furthermore, the Cynodon species classification as auto or allopolyploids is still controversial. Thus, this study aimed to investigate the genomic constitution in diploid and polyploid species using different approaches of genomic in situ hybridization (GISH). To better understand the hybridization events, we also investigated the occurrence of unreduced gametes in C. dactylon diploid pollen grains. We suggest a genomic nomenclature of diploid species as DD, D1D1, and D2D2 for C. dactylon, C. incompletus, and C. nlemfuensis, and DDD2D2 and DD2D1D1 for the segmental allotetraploids of Cynodon dactylon and C. transvaalensis, respectively. Furthermore, an evolutionary proposal was built based on our results and previous data from other studies, showing possible crosses that may have occurred between Cynodon species.

Direct evidence for crossover and chromatid interference in meiosis of two plant hybrids (Lolium multiflorum×Festuca pratensis and Allium cepa×A. roylei).

Crossing over, in addition to its strictly genetic role, also performs a critical mechanical function, by bonding homologues in meiosis. Hence, it is responsible for an orderly reduction of the chromosome number. As such, it is strictly controlled in frequency and distribution. The well-known crossover control is positive crossover interference which reduces the probability of a crossover in the vicinity of an already formed crossover. A poorly studied aspect of the control is chromatid interference. Such analyses are possible in very few organisms as they require observation of all four products of a single meiosis. Here, we provide direct evidence of chromatid interference. Using in situ probing in two interspecific plant hybrids (Lolium multiflorum×Festuca pratensis and Allium cepa×A. roylei) during anaphase I, we demonstrate that the involvement of four chromatids in double crossovers is significantly more frequent than expected (64% versus 25%). We also provide a physical measure of the crossover interference distance, covering ~30-40% of the relative chromosome arm length, and show that the centromere acts as a barrier for crossover interference. The two arms of a chromosome appear to act as independent units in the process of crossing over. Chromatid interference has to be seriously addressed in genetic mapping approaches and further studies.

Identification of ribosomal sites and karyotype analysis in Festuca ulochaeta Steud. and Festuca fimbriata Ness., grasses native to Brazil.

Festuca L. has more than 600 perennial species described, which makes it the largest genus within the family Poaceae. In Brazil, only two native species of Festuca have been described, for which cytogenetic studies need to be strengthened: Festuca ulochaeta and Festuca fimbriata. The aim of this study was to characterize the karyotypes of F. ulochaeta and F. fimbriata based on the mapping of rDNA sites. The FISH was performed with 35S and 5S rDNA probes. Both species have 42 chromosomes, of which 36 were metacentric and six were submetacentric. Festuca fimbriata has two pairs of 35S rDNA sites, one located on the metacentric pair 4, in an interstitial position, and one at the submetacentric pair 14 in the proximal position. Festuca ulochaeta has one pair of 35S rDNA in interstitial-proximal position in the metacentric pair 3. Both species showed 5S rDNA sites only on chromosome pair 21 in the terminal position of the short arm. The analysis of the chromosomal characteristics indicates that these species have a symmetrical karyotype and allopolyploid origin.

45S rDNA sites in meiosis of Lolium multiflorum Lam.: variability, non-homologous associations and lack of fragility.

In this study, we evaluated the behavior of 45S ribosomal DNA (rDNA) sites during the meiosis of Lolium multiflorum. The reason to study it in this species is that 45S rDNA sites are usually visualized as gaps in mitotic metaphase chromosomes and were initially denominated fragile sites (FSs). In different species, FSs were related to rearrangements that alter the karyotype and affect the chromosome pairing in meiosis. However, our findings show that the chromosome pairing in L. multiflorum is regular and, as in mitosis, the number of sites is variable. In diakinesis with five sites, one of the bivalents was in hemizygous state while, in diakinesis with seven sites, one of the bivalents had three conspicuous signals, two in syntheny in one of the homologous. Only four cells had gaps in the region of the 45S rDNA. Owing to the lower number of signals observed at the initial stages of meiosis, it is assumed that they are involved both in homologous and non-homologous associations and that they might assist the chromosome pairing. Regarding segregation, only meiocytes with five and six 45S rDNA signals were observed, and they were characterized by the segregation of 2/3 signals in the poles of anaphases I up to metaphases II; 2/2 and 3/3 in anaphases II and telophases II; and also 2/2 and 4/4 in the nuclei of tetrads, unlike the number of 45S signals expected. The numerical non-equivalence of sites among nuclei at later stages of meiosis is explained by the presence of chromosomes with hemizygous sites.

Relationship between epigenetic marks and the behavior of 45S rDNA sites in chromosomes and interphase nuclei of Lolium-Festuca complex.

The grasses of the Lolium-Festuca complex show a prominent role in world agricultural scenario. Several studies have demonstrated that the plasticity of 45S rDNA sites has been recently associated with the possible fragility of the loci. Often, these fragile sites were observed as extended sites and gaps in metaphases. This organization can be evaluated in relation to their transcriptional activity/accessibility through epigenetic changes. Thus, this study aimed to investigate the relationship of the 5-methylcytosine and histone H3 lysine-9 dimethylation in different conformations of 45S rDNA sites in interphase nuclei and in metaphase chromosomes of L. perenne, L. multiflorum and F. arundinacea. The FISH technique using 45S rDNA probes was performed sequentially after the immunolocalization. The sites showed predominantly the following characteristics in the interphase nuclei: intra- and perinucleolar position, decondensed or partially condensed and hypomethylated and hyper/hypomethylated status. Extranucleolar sites were mainly hypermethylated for both epigenetic marks. The 45S rDNA sites with gaps identified in metaphases were always hypomethylated, which justifies it decondensed and transcriptional state. The frequency of sites with hypermethylated gaps was very low. The structural differences observed in these sites are directly related to the assessed epigenetic marks, justifying the different conformations throughout the cell cycle.

Tratamento de fratura de assoalho orbital com cartilagem conchal / Treatment of orbital floor fracture with conchal cartilage

Introdução: A reconstrução dos defeitos no assoalho orbital após fraturas constitui um desafio ao cirurgião plástico, pois além da expectativa estética e reconstrutora do paciente, cabe o tratamento de possíveis complicações funcionais, como diplopia e parestesias faciais. O objetivo é demonstrar uma série de casos utilizando cartilagem auricular conchal para reposição volumétrica orbital e estrutural do assoalho. Métodos: Foram avaliados 24 pacientes, operados pelo autor deste trabalho no período de 2013 a 2016, por motivo de fraturas de assoalho orbital pura (blow-out) ou impura (conjugadas a lesões de margem orbital, como zigoma e maxila). A técnica de estruturação do assoalho utilizou enxerto cartilaginoso autólogo conchal em todos os casos. Os pacientes foram catalogados quanto à presença de queixas pré-operatórias, como parestesia e diplopia, e sintomas, como enoftalmia, assim como resultados pós-operatórios. Resultados: A presença de lesões concomitantes como fratura de complexo zigomático e fratura maxilar pode influenciar no sucesso da reconstrução, assim como as fraturas com maior área de descontinuidade no assoalho orbital. Poucos pacientes apresentaram queixas pós-operatórias e somente dois casos (9,2%) necessitaram de nova abordagem cirúrgica. Conclusão: A cartilagem conchal auricular autóloga é um material adequado à reconstrução de defeitos no assoalho orbital pós-fratura, apresentando como vantagens a fácil obtenção, baixa morbidade, cicatriz inconspícua, excelente adaptação ao formato do assoalho da órbita e consequente reposição volumétrica.

Introduction: The reconstruction of defects in the orbital floor after fractures poses a challenge to the plastic surgeon because besides the patient's aesthetic and reconstructive expectations, possible functional complications such as diplopia and facial paresthesia must be treated. This study aimed at reporting a series of cases in which conchal auricular cartilage was used for volumetric orbital and structural replacement of the floor. Methods: Twenty-four patients, with surgery performed by the author, between 2013 and 2016, for pure (blow-out) or impure (conjugated to orbital margin injuries, such as zygoma and maxilla) orbital floor fractures, were evaluated. The repair technique involved autologous conchal cartilage graft in all cases. Patients were classified for the presence of preoperative complaints, including paresthesia and diplopia, and symptoms such as enophthalmia, as well as postoperative outcomes. Results: The existence of concomitant lesions, such as zygomatic complex and maxillary fracture, as well as fractures with greater discontinuity in the orbital floor, may influence the success of reconstruction. Few patients exhibited postoperative complaints and only two (9.2%) required a new surgical approach. Conclusion: Autologous conchal auricular cartilage is a suitable material for reconstruction of defects in the post-fracture orbital floor, possessing various advantages, including ease of attainment, low morbidity, inconspicuous scar, and excellent adaptation to the shape of the orbital floor and consequent volumetric replacement.

Prescriçäo de medicamentos por balconistas de 72 farmácias de Belo Horizonte/MG em maio de 1983: riscos de acidentes / Prescription of drugs by attendants of 72 pharmacies of Belo Horizonte/MG in may of 1983: risks of accidents

Apresentam-se resultados de inquérito realizado entre os dias 20 e 27 de maio de 1983, com atendentes em farmácias de Belo Horizonte. Foram analisadas as suas condutas frente a um caso clínico hipotético: uma criança, näo apresentada ao atendente, com febre, vômitos e diarréia hás seis horas. Das 72 condutas analisadas, em 13 (18%) houve recomendaçäo de procurar um serviço médico. Nas 59 (82%) restantes, os balconistas prescreveram predominantemente medicamentos para tratamento sintomático e antibióticos. Além disso, medicamentos com associaçäo de drogas foram prescritos. Observou-se a poliprescriçäo medicamentosa, fato que levou a um custo médio por receita correspondente a 3,8% do salário mínimo vigente. Destacam-se as conseqüências médicas, econômicas e sociais desta prática e assinalam a importância de uma maior conscientizaçäo dos profissionais da área de saúde para o problema, além de possíveis efeitos de intoxicaçäo e interaçäo medicamentosa, tendo em vista que houve diferença estatisticamente significativa (p < 0,05) entre farmacêuticos e balconistas com relaçäo ao ato de prescrever, onde os últimos executaram mais vezes tal conduta. A diminuiçäo desta prática contribuirá para o decréscimo das intoxicaçöes medicamentosas, que ocupam o primeiro lugar em nosso meio, dentre todos os tipos delas