Clonal growth and dispersal potential of Leiothrix flagellaris Ruhland (Eriocaulaceae) in the rocky grasslands of Southeastern Brazil

Leiothrix flagellaris is a small clonal plant that grows in sandy/rocky, nutrient poor soils in the rocky grasslands ("campos rupestres") of southeastern Brazil. In the rainy season most of their flower heads differentiate into small rosettes, produced by pseudovivipary, and connected to the mother-plant by flexible, elongated stalks that can reach up to 90cm. Most of these rosettes remain suspended over rocks or over the sparse herbaceous surrounding vegetation, while a few arch low enough to come into contact with the surrounding soil and take root. These suspended rosettes can reach diameters comparable to currently rooted and reproductively active rosettes produced during previous reproductive periods. As the rooted rosettes grow up, their potential to generate and disperse new pseudoviviparous rosettes increase rapidly. This unusual guerrilla strategy of L. flagellaris seems to congregate a suit of traits that promote a fast increase in photosynthetic area and improve recruitment, thereby helping to circumvent dispersal and establishment failures in its severe environment.

Influence of soil properties on the abundance of plant species in ferruginous rocky soils vegetation, southeastern Brazil

Ferruginous "campos rupestres" are a particular type of vegetation growing on iron-rich primary soils. We investigated the influence of soil properties on plant species abundance at two sites of ferruginous "campos rupestres" and one site of quartzitic "campo rupestre", all of them in "Quadrilátero Ferrífero", in Minas Gerais State, southeastern Brazil. In each site, 30 quadrats were sampled to assess plant species composition and abundance, and soil samples were taken to perform chemical and physical analyses. The analyzed soils are strongly acidic and presented low fertility and high levels of metallic cations; a principal component analysis of soil data showed a clear segregation among sites due mainly to fertility and heavy metals content, especially Cu, Zn, and Pb. The canonical correspondence analysis indicated a strong correlation between plant species abundance and soil properties, also segregating the sites.

Habitat utilization and CAM occurrence among epiphytic bromeliads in a dry forest from southeastern Brazil

We studied the community and habitat occupation of epiphytes to understand how these plants cope with a supposedly stressful habitat: i) how general epiphytes occupy tree trunks, ii) how epiphytic bromeliads, occupy their supportive trees, iii) how CAM bromeliads are spatially distributed. The study was done in the dry forest of Jacarepiá, State of Rio de Janeiro. Data collection on epiphytes, phorophytes, and trees was based on the point-center quarter method. The photosynthetic pathway of the bromeliad species was determined using isotope ratio mass spectrometry. The presence of Gesneriaceae, Araceae, and Cactaceae indicates that some humidity is present in the area allowing the presence of supposedly less-specialized epiphytes. There was no correlation between epiphyte abundance and phorophyte diameter, and phorophytes had larger sizes than trees that do not host epiphytes. There was correlation between tree diameter and bromeliad abundance, and lack of correlation between diameter and bromeliad richness. Only one species was typical of the understorey and one was typical of the canopy, while intermediate heights were occupied by different species. The only C3 bromeliad species (Vriesea procera (Mart. ex Schult.f.) Wittm.) was significantly more exposed than the other species. If CAM occurrence is related to water economy, the fact that a C3 species is subjected to more exposed conditions is remarkable. Further comments are presented on the proportion between CAM bromeliad species and abundance in dry forest. Regarding life forms, holoepiphytes, as opposed to hemiepiphytes, showed not to be restricted by the phorophyte's diameter suggesting a more successful establishment of this life form.

Leaf damage in a mangrove swamp at Sepetiba Bay, Rio de Janeiro, Brazil

Leaf damage to Rhizophora mangle L., Avicennia schaueriana Stapf. & Leechman, and Laguncularia racemosa L. was studied in a two hectare mangrove swamp site in Sepetiba Bay. Seventeen arthropod morphospecies were identified as being responsible for the damage, and their species diversity was highest on A. schaueriana, followed by R. mangle and L. racemosa. Damage in terms of relative area was greatest in L. racemosa. Almost 9% of mangrove canopy leaf area demonstrated some damage. Loss of leaf area to herbivory was 12.1%, 8.3% and 6.2% in L. racemosa, A. schaueriana and R. mangle respectively. L. racemosa and A. schaueriana showed high percentages of leaf-margin damage in terms of the total damaged leaf area (82.2% and 56.3% respectively), while the most important type of damage in R. mangle was necrosis, representing 58.1% of the total damaged leaf area.

Plant-plant associations and population structure of four woody plant species in a patchy coastal vegetation of Southeastern Brazil

We examined plant population structure and interspecific associations for juveniles and adults of four woody species (Andira legalis (Vell.) Toledo, Clusia hilariana Schltdl., Protium icicariba (DC.) Marchand and Vernonia crotonoides Sch. Bip. ex Baker) in a patchy vegetation on a sandy coastal plain (restinga) in SE - Brazil. We found 101 vegetation patches in a 0.5 ha grid and these were divided into two distinct size classes, with large patches (> 20 m²) containing the majority of adult individuals of the species studied. The most abundant species, P. icicariba (465 individuals) and C. hilariana (312), had actively regenerating populations, whereas A. legalis (20) and V. crotonoides (338) showed evidence of intermittent regeneration. The regeneration niches of the four species differed as did their investment in vegetative reproduction: for instance, 81% of C. hilariana seedlings were found growing inside tank-bromeliads contrasting with only 3% of P. icicariba in this habitat. Additionally, 28% of regenerants of C. hilariana originated vegetatively, contrasting with only 6% for P. icicariba. All significant associations between species found in the study were positive. There was a positive association between adults of C. hilariana and P. icicariba, as well as between adults of C. hilariana and juveniles of both. This suggests that P. icicariba is successfully establishing under the canopy of C. hilariana and highlights the role of C. hilariana in generating vegetation cover that will be later dominated by other woody plant species, as an important process for maintenance of plant diversity in this restinga vegetation.

Reproductive biology of Protium spruceanum (Burseraceae), a dominant dioecious tree in vegetation corridors in Southeastern Brazil

We investigated the reproductive biology of Protium spruceanum (Benth.) Engler in vegetation corridors of secondary Atlantic forest in Lavras, southern Minas Gerais State, Brazil. The reproductive phenology was investigated fortnightly over a one year period. Floral biology studies involved pollen viability analysis, nectar production, stigmatic receptivity, pollen tube growth, visiting insect species and visit rates. The small, pale yellowish flowers (0.3-0.4 cm diameter) are functionally unisexual and organized in dense inflorescences (ca. 45 flowers). P. spruceanum presented annual flowering between September and November. Staminate flowers supplied a high percentage of viable pollen (90.6%) and relatively abundant nectar (x = 4.5 μL). Pistillate flowers produced only nectar to flower visitors (x = 4.0 μL). The effective pollinators were Apis mellifera and Trigona sp. (Hymenoptera, Apidae). Pollen tubes of cross-pollinated flowers were observed entering the ovaries 48 h after pollination. The fruiting season is from October to March, with a peak in November, coinciding with the rainfall peak. Ecological implications of these findings, and alternative arguments to explain the high genetic diversity at regional landscape are discussed.

Floristic relationships among inland swamp forests of Southeastern and Central-Western Brazil

We evaluated the floristic relationships among 20 swamp forests of Southeastern and Central-Western Brazil using multivariate analyses. Detrended correspondence analysis (DCA) and TWINSPAN (Two way indicator species analysis) indicated two distinct floristic groups among forests, according to the Phytogeographic Province (Paranaense or Cerrado) and their climate conditions, phytophysiognomies, and species composition. Within the same province, edaphic conditions and geographical distance, among other factors, may be responsible for similarities or dissimilarities among the forests floras. Our results indicated that, despite the low a diversity, γ diversity is high among the forests, as a result of the low floristic similarities among the remnants and the high number of unique species (55% of all species). Although floristically distinct, we concluded that the inland swamp forests of Southeastern Brazil and the gallery swamp forests of Central Brazil are part of the same forest formation. These forests have in common, in addition to the swampy environment, low plant species diversity and species that have high local densities, such as Calophyllum brasiliense Cambess., Cecropia pachystachya Trécul, Dendropanax cuneatus Decne. & Planch., Guarea macrophylla Vahl, Magnolia ovata (A. St.-Hil.) Spreng., Protium spruceanum (Benth.) Engl. and Tapirira guianensis Aubl.

Allozyme variation in a natural population of Stryphnodendron adstringens in the Rio Preto State Park, southeastern Brazil

Leaves and fruits from 63 Stryphnodendron adstringens trees were sampled in the Rio Preto State Park to analyze allozyme segregation, tissue specific expression of allozyme loci, and their genetic parameters. The enzyme systems ADH, EST, ACP, PGM, PGI, GDH, G6PDH, GOT, IDH, LAP, MDH, PER and SKDH were assessed by means of starch-gel electrophoresis. The polymorphic systems PGI, IDH, MDH and GOT demonstrated a dimeric quaternary structure, while EST and PER were monomeric. The total expected genetic diversity (H E) for leaves and seeds were 0.325 and 0.244 respectively. The effective number of alleles per locus (A E) was 1.58 in leaves and 1.42 in seeds. The values of H E and A E observed in S. adstringens were comparatively higher than the average values seen in allozyme studies of other woody plants. The values of the fixation indices for the population, considering leaves (f = 0.070) and seeds (f = 0.107), were not significant. The high values of genetic diversity and of effective number of alleles per locus, as well as the non-significant fixation index and the adjustments of the Hardy-Weinberg proportions between generations for the pgi-1, mdh-2 and idh-1 loci, indicated random mating in this population. The enzyme systems EST and PER demonstrated their best resolution in leaf tissues, while the MDH, IDH, PGI and GOT systems demonstrated their best resolution in seed tissues.

Maternal age and Down syndrome in Southeastern Brazil

The proportion of maternal-age-independent patients estimated among 200 Brazilian Down syndrome children (59.6%) was significantly larger than that of maternal-age-dependent cases (40.4%). The latter proportion is the smallest observed in pertinent literature and due basically to the low mean maternal age of the population analyzed. Based on the remarkable correlation (r = 0.95) between the proportion of maternal-age-dependent patients and the mean maternal age of the general population, a simple predictive equation to estimate the proportion of maternal-age-dependent Down syndrome patients based on the mean maternal age of the general population is suggested in situations where reliable data on the incidence of this syndrome according to maternal age is not available.

Ocurrence of Vibrio spp., positive coagulase staphylococci and enteric bacteria in oysters (Crassostrea gigas) harvested in the south bay of Santa Catarina island, Brazil

The aim of this study was to assess the contamination of oysters (Crassostrea gigas), harvested in six different regions of the South Bay of Santa Catarina Island, with Coliforms at 45 ºC, Escherichia coli, Vibrio spp., positive coagulase staphylococci, and Salmonella sp. over a period of one year. One hundred eighty oyster samples were collected directly from their culture sites and analyzed. Each sample consisted of a pool of 12 oysters. All of the samples analyzed showed absence of Salmonella, 18 (10%) samples showed presence of Escherichia coli, 15 (8.3%) samples were positive for V. alginolyticus, and Vibriocholerae was detected in 4 samples (2.2%). The counts of positive-coagulase staphylococci varied from <10 to 1.9 x 102 CFU.g-1, whereas the counts of Coliforms at 45 ºC and E. coli ranged from <3 to 1.5 x 102 MPN.g-1 and <3 and 4.3 x 10 MPN.g-1, respectively. Counts of V. parahaemolyticus and V. vulnificus ranged between <3 and 7 MPN.g-1, for both microorganisms. This suggests the need for monitoring these Vibrios contamination in oysters. Based on the results of the microbiological assays, the samples analyzed showed acceptable bacteriological quality, i.e., they were within the parameters established by Brazilian Legislation.