This work aimed to verify the genetic variability of Fusarium oxysporum f. sp. cubense isolates based on aggressiveness and molecular data (ISSR, SSR and sequencing of the TEF-1α gene). A total of 152 isolates collected from bananaproducing areas in the north and south regions of the state of Santa Catarina, Brazil, were compared. Isolates were collected from plants belonging to the Pome and Cavendish subgroups. Pathogenicity was confirmed for all isolates, and morphological traits confirmed the identity of the fungus. Greenhouse assays allowed classification of the isolates into three groups according to their aggressiveness. Results from ISSR, SSR and DNA sequencing revealed less variation since the majority of the isolates displayed 100 % similarity. Among the markers, ISSR and SSR were the most polymorphic in terms of differentiating with a larger percentage of dissimilarity. Results from aggressiveness tests indicated a tendency towards a consistent structure according to host or geographical origin of the isolates. No relationship between DNA markers and aggressiveness of isolates could be established.

The present study was conducted to define a methodology to produce and store small-scale microalgae paste to be used in a mollusk hatchery. Microalgae were cultured in 500 L fiberglass tanks, under temperature of 20 6 2 C, Guillard f/2 culture medium, and continuous light intensity of 203-226 mmol photons/m 2 /sec. Cultures were centrifuged at 2000 g at the exponential growth phase. Microalgae cell quality after centrifugation and during storage was determined by analyses with Evan's blue stain and by counting the number of total marine bacteria. Treatments with and without additive were applied to the microalgae paste produced, which was distributed into 100 mL plastic containers, capped, and stored under refrigeration at 4 6 1 C. Results indicated that in the Chaetoceros muelleri paste, centrifugation did not damage the cells and the number of total marine bacteria reduced significantly from 2.9 3 10 6 to 8.3 3 10 5 colony-forming units per milliliter. Chaetoceros muelleri and Chaetoceros calcitrans pastes stored with addition of 0.1% ascorbic acid had a shelf life shorter than 2 wk. For the treatment without additive, results with Evan's blue stain showed that cells (99%) remained viable until the sixth week of storage for C. muelleri and seventh week of storage for Skeletonema sp. and C. calcitrans. The number of bacteria did not increase during storage for C. calcitrans and Skeletonema (P . 0.05). For C. muelleri, an increase in bacteria (P , 0.05) was observed after the sixth week of storage. This study demonstrated the feasibility to produce and store microalgae paste for a period of 2-8 wk, which allows it to be used as food source and also optimizes the use of microalgae cultured in laboratory.

ABSTRACT. Croton antisyphiliticus Mart. is a medicinal plant native to Cerrado vegetation in Brazil, and it is popularly used to treat urogenital tract infections. The objective of the present study was to assess the genetic variability of natural C. antisyphiliticus populations using AFLP molecular markers. Accessions were collected in the states of Minas Gerais, São Paulo, and Goiás. The genotyping of individuals was performed using a LI-COR ® DNA Analyzer 4300. The variability within populations was found to be greater than the variability between them. The F ST value was 0.3830, which indicated that the populations were highly structured. A higher percentage of polymorphic loci (92.16%) and greater genetic diversity were found in the population accessions from Pratinha-MG. Gene flow was considered restricted (N m = 1.18), and there was no correlation between genetic and geographic distances. The populations of C. antisyphiliticus exhibited an island-model structure, which demonstrates the vulnerability of the species.

This study evaluated the performance and cold tolerance of different Nile tilapia stocks, selected at suboptimal temperature and identified alleles of microsatellite markers associated with cold tolerance. After 67 days of rearing at average temperature of 22.4°C, tilapia juveniles from different stocks were evaluated, tagged with a transponder and acclimated to 16°C. Subsequently, the temperature was reduced 1°C per day until 11°C and from that temperature decreases of 0.5°C per day were made until total mortality. A caudal fin sample was collected, and their genetic profile was characterized through the microsatellite markers UNH879, UNH916 and UNH999. Tilapias of stocks S3, S6 and S7 showed higher growth at suboptimal temperatures, 42 to 47% higher than base population. In the cold tolerance assay, tilapias from stocks S5 and S7 showed lower mean death temperature. Through molecular analysis, it is stated that allele 186 bp of UNH879 and 147 bp of UNH916 were more frequently found in animals cold‐tolerant. Artificial selection for final weight during winter in southern Brazil can assist in the selection of tilapias improved to rearing in suboptimal temperatures. Finally, using microsatellite markers, it is possible to direct selective breeding to obtain tilapias more adapted to low temperatures.

We analysed the settling rate of Nodipecten nodosus L. scallop spats during winter and spring, testing different types of collectors and collector preparation periods. Larval rearing was conducted with water exchange every 48 h, density at 2 larvae mL−1 and feeding between 0.5 and 2 × 104 microalgae cellsmL−1. The recovery larvae based on D‐larvae produced were 31.6% (Winter Trial) and 47.2% (Spring Trial), without any antibacterial additives. The mean settling rates obtained in Winter Trial were from 0.04% to 0.79% withstand in Spring Trial were 24.99–48.65%. In the Winter Trial, there was no statistical difference between the settling rate of collectors prepared for 6 or 12 days. The settling rates of the netlon collectors with pine leaves were up to 19 times higher than those of the other types of collectors. In the Spring Trial, there was no statistical difference between the settling rates of the netlon and plastic net fruit collectors. Collectors with pine leaves produced a yield of spats up to 48.65%, more than those without pine leaves (P<0.01). The efficiency of larval rearing and settling obtained in spring, pine leaves and low‐cost local material indicate the feasibility to improve and facilitate regular production of N. nodosus spats for promotion of the growth of scallop culture in Brazil.