Eleocharis subarticulata is recorded as the third species of Cyperaceae with a reduced chromosome number ( n = 3), following reports on Rhynchospora tenuis ( n = 2) and Fimbristylis umbellaris ( n = 3). For Eleocharis, the numbers recorded to date vary from 2 n = 10 to 2 n = c. 196, with x = 5 as the possible basic number. The karyotype of E. subarticulata was studied using conventional staining (mitosis and meiosis), C-CMA 3 /DAPI banding, and FISH with 45S rDNA and telomere probes. The chromosomes showed no primary constrictions, as expected in the holocentric chromosomes of Cyperaceae. The meiotic behaviour was abnormal, with a single multivalent ring of six chromosomes at metaphase I, resulting from multiple translocations. At anaphase I six chromatids migrated to each pole, evidencing the inverted meiosis, and these groups were also visible at metaphase II. The C-CMA 3 /DAPI banding technique showed only four terminal GC-rich blocks. FISH with 45S rDNA probes revealed four terminal signals, probably associated with GC-rich blocks. The telomeric probe located terminal signals in all the chromosomes, besides a hybridization site in the middle of the large pair. The occurrence of ectopic telomeric sites has not been described previously for plants with holokinetic karyotypes and with reduced chromosome numbers. These data reinforce the hypothesis of the reduction in chromosome number by multiple translocations.

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Plant genomes are massively invaded by transposable elements (TEs), many of which are located near host genes and can thus impact gene expression. In flowering plants, TE expression can be activated (de-repressed) under certain stressful conditions, both biotic and abiotic, as well as by genome stress caused by hybridization. In this study, we examined the effects of these stress agents on TE expression in two diploid species of coffee, Coffea canephora and C. eugenioides, and their allotetraploid hybrid C. arabica. We also explored the relationship of TE repression mechanisms to host gene regulation via the effects of exonized TE sequences. Similar to what has been seen for other plants, overall TE expression levels are low in Coffea plant cultivars, consistent with the existence of effective TE repression mechanisms. TE expression patterns are highly dynamic across the species and conditions assayed here are unrelated to their classification at the level of TE class or family. In contrast to previous results, cell culture conditions per se do not lead to the de-repression of TE expression in C. arabica. Results obtained here indicate that differing plant drought stress levels relate strongly to TE repression mechanisms. TEs tend to be expressed at significantly higher levels in non-irrigated samples for the drought tolerant cultivars but in drought sensitive cultivars the opposite pattern was shown with irrigated samples showing significantly higher TE expression. Thus, TE genome repression mechanisms may be finely tuned to the ideal growth and/or regulatory conditions of the specific plant cultivars in which they are active. Analysis of TE expression levels in cell culture conditions underscored the importance of nonsense-mediated mRNA decay (NMD) pathways in the repression of Coffea TEs. These same NMD mechanisms can also regulate plant host gene expression via the repression of genes that bear exonized TE sequences.

ABSTRACT. Species composition, relative abundance, seasonal changes in the species abundance and scent association of male Euglossini collected in a semi-deciduous forest fragment in the north of the State of Paraná, southern Brazil, were recorded. Euglossine males were collected twice a month, for twelve months, from 8:00 am to 3:00 pm. The scents eucalyptol, eugenol, vanillin, methyl salicylate and benzyl acetate were used as baits. A total of 434 males distributed among 3 genera and 9 species were attracted to the chemical baits. Cockerell, 1904 (0.23%) and Eufriesea auriceps Friese, 1899 (0.23%). In general, bees were more abundant in warm-wet season (September-March). Eufriesea violacea was the most seasonal species, showing activity through the warm-wet season, from October to February. Eucalyptol was the most attractive fragrance, which was responsible for 92.6% of all visits by euglossine bees.

The genus Rhynchospora Vahl. (Cyperaceae) has about 270 species, two subgenera and 27 sections. Cytogenetic studies showed that polyploidy is the main mechanism of numeric changes in the karyotypes of Rhynchospora. However, some species have exhibited some evidence of agmatoploidy and symploidy. The occurrence of holocentric chromosomes seems to support more the events of fusion (symploidy) and fission (agmatoploidy), leading to the appearance and maintenance of intra-and interspecific variations based in disploidy. In this study, chromosome counts and recounts were performed in 14 species obtained from different Brazilian localities. New chromosome numbers have been reported for R. tenuis, R. globosa, R. pubera, R. nervosa, R. junciformis and R. asperula. The analysis showed the absence of primary constrictions on the chromosomes and numeric variation from 2n = 4 to 2n = 58. The primary (x = 5) and secondary (x = 6 and 9) basic numbers were again confirmed. Our results expand the information related to chromosome rearrangements in Rhynchospora and reinforce the role of polyploidy and dysploidy in karyotype differentiation in representatives of Cyperaceae.

Bacillus thuringiensis is an important microbial control agent against insect pests. The draft genome sequence of the Brazilian strain BR58 described here contains the insecticidal genes cry4A, cry4B, cry10A, cry11A, cry60A, cry60B, and cyt1A, which show toxicity to both Aedes aegypti and Hypothenemus hampei larvae.

B chromosomes are additional elements to standard karyotypes observed in different species of fishes, especially in Curimatidae. However, despite studies demonstrating the occurrence of Bs, little is known about their origin and evolution. To better understand the genomic composition and evolutionary processes involving B chromosomes, microdissection of B microchromosomes in Steindachnerina insculpta was conducted. Chromosome painting revealed the totally hybridized B and markings on A chromosomes both in S. in sculpta and in Cyphocharax spilotus, demonstrating a strong homology between these different species. In specimens of C. modestus, which do not have Bs, the signals were observed on A chromosomes. Cloning and sequencing of some B fragments revealed that the B microchromosome in S. insculpta is composed of repetitive elements, homologous to the DIRS-4 LTR retrotransposon of Xenopus (Silurana) tropicalis. FISH with clone pSi48 with the DIRS-4 retroelement revealed signals on all A chromosomes in the 2 species and also on the B, suggesting the insertion of repetitive elements in these species.

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