Aspects of gene regulation in the diploid and tetraploid Odontophrynus americanus (Amphibia, Anura, Leptodactylidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ineffectiveness of pruning to control citrus huanglongbing caused by Candidatus Liberibacter americanus

The huanglongbing (HLB) disease of citrus trees, caused by Candidatus Liberibacter asiaticus and Ca. Liberibacter americanus, was first reported in Brazil in March, 2004. The presence of the disease has caused serious concerns among growers. Pruning experiments were conducted to determine if removal of symptomatic branches or the entire canopy (decapitation) would eliminate infected tissues and save HLB-affected trees. Pruning was done in five blocks on a total of 592 3- to 16 year-old 'Valencia', 'Hamlin' or 'Pera' sweet orange trees showing no symptoms or with two levels of symptom severity. Ten decapitated trees per block were caged and all trees were treated with insecticides to control the psyllid vector, Diaphorina citri. Mottled leaves reappeared on most symptomatic (69.2%) as well on some asymptomatic (7.6%) pruned trees, regardless of age, variety, and pruning procedure. Presence of the pathogen (Ca. Liberibacter americanus) in all symptomatic trees was confirmed by PCR. In general, the greater the symptom severity before pruning the lower the percentage of trees that remained asymptomatic after pruning.

Candidatus Liberibacter americanus, associated with citrus huanglongbing (greening disease) in São Paulo State, Brazil

Symptoms of huanglongbing (HLB) were reported in São Paulo State (SPS), Brazil, in March 2004. In Asia, HLB is caused by 'Candidatus Liberibacterasiaticus'and in Africa by 'Candidatus Liberibacter africanus'. Detection of the liberibacters is based on PCR amplification of their 16S rRNA gene with specific primers. Leaves with blotchy mottle symptoms characteristic of HLB were sampled in several farms of SIPS and tested for the presence of liberibacters. 'Ca. L. asiaticus' was detected in a small number of samples but most samples gave negative PCR results. Therefore, a new HLB pathogen was suspected. Evidence for an SPS-HLB bacterium in symptomatic leaves was obtained by PCR amplification with universal primers for prokaryotic 16S rRNA gene sequences. The amplified 16S rRNA gene was cloned and sequenced. Sequence analysis and phylogeny studies showed that the 16S rRNA gene possessed the oligonucleotide signatures and the secondary loop structure characteristic of the alpha-Proteobacteria, including the liberibacters. The 16S rRNA gene sequence phylogenetic tree showed that the SPS-HLB bacterium clustered within the a-Proteobacteria, the liberibacters being its closest relatives. For these reasons, the SPS-HLB bacterium is considered a member of the genus 'Ca. Liberibacter'. However, while the 16S rRNA gene sequences of 'Ca. L. asiaticus' and 'Ca. L. africanus' had 98-4% similarity, the 16S rRNA gene sequence of the SPS-HLB liberibacter had only 96(.)0% similarity with the 16S rRNA gene sequences of 'Ca. L. asiaticus'or'Ca. L. africanus'. This lower similarity was reflected in the phylogenetic tree, where the SPS-HLB liberibacter did not cluster within the 'Ca. L asiaticus'/'Ca. L. africanus group', but as a separate branch. Within the genus 'Candidatus Liberibacter' and for a given species, the 16S/23S intergenic region does not vary greatly. The intergenic regions of three strains of 'Ca. L. asiaticus', from India, the People's Republic of China and Japan, were found to have identical or almost identical sequences. In contrast, the intergenic regions of the SPS-HLB liberibacter, 'Ca. L. asiaticus' and 'Ca. L. africanus' had quite different sequences, with similarity between 66(.)0 and 79(.)5%. These results confirm that the SPS-HLB liberibacter is a novel species for which the name 'Candidatus Liberibacter americanus' is proposed. Like the African and the Asian liberibacters, the 'American' liberibacter is restricted to the sieve tubes of the citrus host. The liberibacter could also be detected by PCR amplification of the 16S rRNA gene in Diaphorina citri, the psyllid vector of 'Ca. L. asiaticus', suggesting that this psyllid is also a vector of 'Ca. L. americanus' in SPS. 'Ca. L. americanus' was detected in 216 of 218 symptomatic leaf samples from 47 farms in 35 municipalities, while 'Ca. L. asiaticus' was detected in only 4 of the 218 samples, indicating that 'Ca. L. americanus' is the major cause of HLB in SIPS.

Sex ratio, growth and recruitment of the pelagic shrimp Acetes americanus on the southeastern coast of Brazil

We evaluated the population dynamics of Acetes americanus Ortmann, 1893 focusing on sex ratio, individual growth, longevity, and the juvenile recruitment period. Samples were collected monthly from January 2006 to June 2007 in the bay of Ubatuba, Brazil. Specimen growth was identified for each gender, and the chosen cohorts were fitted in a von Bertalanffy Growth Model (VBGM); longevity was estimated by the von Bertalanffy inverse equation, considering 99% of the asymptotic length. A total of 6881 individuals (2343 males and 4538 females) were captured. On average the body size (total length) was greater in females (14.64 ± 3.34 mm) than in males (12.27 ± 1.86 mm). The mean growth curves (obtained by grouping the cohorts for each sex), provided estimates of TL∞ = 19.33 mm, k = 0.02 and t0 = -0.12 days for females and TL∞ = 15.13 mm, k = 0.03 and to = -0.07 days for males, where TL∞ is the asymptotic length, k is coefficient of growth and to is the theorical age when the size is equal to 0. Longevity was estimated at 0.61 years for females and 0.50 years for males. The sex ratio tended to favor females, which corroborates with others studies of sergestids. Our finding that males of A. americanus have higher values of k and therefore achieve a smaller size relative to females has been observed in other penaeids. We concluded that this differential growth pattern between the sexes is found across Dendrobranchiata. The life cycles of penaeids have an average duration of approximately 1-2 years, but our results corroborate other studies that estimate a shorter longevity for Acetes, as species of this genus are typically smaller in size. We found continuous recruitment with two main peaks observed during the study period, corroborating previous studies of Acetes. © The Crustacean Society, 2013. Published by Brill NV, Leiden.

Distribution related to temperature and salinity of the shrimps Acetes americanus and Peisos petrunkevitchi (Crustacea: Sergestoidea) in the south-eastern Brazilian littoral zone

The abundance and ecological distribution of Acetes americanus and Peisos petrunkevitchi were investigated from July 2006 to June 2007, in Ubatuba, Brazil. Eight transects were identified and sampled monthly: six of these transects were located in Ubatuba bay, with depths reaching 21 m, and the other two transects were in estuarine environments. A total of 33,888 A. americanus shrimp were captured, with the majority coming from the shallower transects (up to 10 m). Conversely, 6,173 of the P. petrunkevitchi shrimps were captured in deeper areas (from 9 to 21 m). No individuals from either species were found in the estuary. The highest abundances obtained for both species were sampled during the summer. Canonical correlation analysis resulted in a coefficient value of 0.68 (P = 0.00). The abundance of both species was strongly correlated with depth. Variations in temperature and salinity values were also informative in predicting the seasonal presence of P. petrunkevitchi in deeper areas and A. americanus in the shallower areas of the bay. It is conceivable that the shrimp adjust their ecological distribution according to their intrinsic physiological limitations. © 2012 Marine Biological Association of the United Kingdom.

Distribuição de Candidatus Liberibacter americanus e Candidatus Liberibacter asiaticus em plantas cítricas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Repetitive DNA chromosomal organization in the cricket Cycloptiloides americanus: a case of the unusual X(1)X(2)0 sex chromosome system in Orthoptera

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

POPULATION BIOLOGY AND DIET OF THE SOUTHERN KINGCROAKER Menticirrhus americanus (LINNAEUS, 1758) (PERCIFORMES: SCIAENIDAE) IN CARAGUATATUBA BAY, SOUTHEASTERN BRAZIL

This study evaluated the spatio-temporal distribution, population biology and diet of Menticirrhus americanus in Caraguatatuba Bay. Samples were taken monthly between August 2003 and October 2004, by trawling in two previously selected areas. The northern area is more exposed to wave activity and is influenced by a river, functioning as a small estuary. In contrast, the southern area is relatively sheltered from wave energy and influenced to a lesser degree by smaller rivers. The fishes' length was measured, and the sex and gonadal stage macroscopically identified. The abundance of this species was compared between areas and among months. The diet was identified and quantified. M. americanus occurred in equal proportions in the two study areas, being most abundant in April 2004, followed by December 2003 and January 2004. The population was dominated by small immature individuals. The few individuals in maturation or mature that were captured showed no seasonal pattern of distribution. This species had a varied diet, feeding on worms (nemerteans, sipunculans and echiurans), mollusks (bivalves and cephalopods), polychaetes, crustaceans and fish. The presence of intact nematodes in the intestine suggests that these are parasites. The results demonstrated that M. americanus has a homogeneous spatial and temporal distribution in Caraguatatuba Bay, being uniformly distributed between the south and north areas as well as across the months. This species can be considered a carnivorous predator, showing a preference for consuming benthic sandy-beach species such as glycerids and other polychaetes, crustaceans, and bivalve siphons.

Population biology and diet of the southern kingcroaker Menticirrhus americanus (Linnaeus, 1758) (Perciformes: Sciaenidae) in Caraguatatuba Bay, southeastern Brazil

This study evaluated the spatio-temporal distribution, population biology and diet of Menticirrhus americanus in Caraguatatuba Bay. Samples were taken monthly between August 2003 and October 2004, by trawling in two previously selected areas. The northern area is more exposed to wave activity and is influenced by a river, functioning as a small estuary. In contrast, the southern area is relatively sheltered from wave energy and influenced to a lesser degree by smaller rivers. The fishes' length was measured, and the sex and gonadal stage macroscopically identified. The abundance of this species was compared between areas and among months. The diet was identified and quantified. M. americanus occurred in equal proportions in the two study areas, being most abundant in April 2004, followed by December 2003 and January 2004. The population was dominated by small immature individuals. The few individuals in maturation or mature that were captured showed no seasonal pattern of distribution. This species had a varied diet, feeding on worms (nemerteans, sipunculans and echiurans), mollusks (bivalves and cephalopods), polychaetes, crustaceans and fish. The presence of intact nematodes in the intestine suggests that these are parasites. The results demonstrated that M. americanus has a homogeneous spatial and temporal distribution in Caraguatatuba Bay, being uniformly distributed between the south and north areas as well as across the months. This species can be considered a carnivorous predator, showing a preference for consuming benthic sandy-beach species such as glycerids and other polychaetes, crustaceans, and bivalve siphons.

Aggression and its function as a hub mediating host defense against the slavemaking ant Protomognathus americanus

In meiner Dissertation beschäftigte ich mich mit unterschiedlichen Verteidungsstrategien, derenrnEffektivität und Evolution, der Ameisenart Temnothorax longispinosus (“Sklaven”), gegenüberrneinem sozialen Parasiten - der nahverwandten, sklavenhaltenden Art Protomognathusrnamericanus (“Sklavenhalter”). Wir entdeckten eine neue Kategorie der Verteidigungsstrategie,rnwelche es dem Wirten ermöglicht, flexibel auf die nicht vorhersagbaren Angriffe des Parasitenrnzu reagieren. Darüber hinaus erforschten wir, wie die Wirte ihre kollektive Verteidigung an einernVielzahl unterschiedlicher Angreifer anpassen können. Wir konnten feststellen, dass Wirte in derrnLage sind ihre kollektive Verteidigung dem Grad der Bedrohung anzupassen. Dies weist daraufrnhin, dass Selektion die Verteidigung gegen unterschiedliche Typen von Angreifern voneinanderrnunabhängig beeinflussen könnte. In einer dritten Studie belegten wir experimentell, dass diernParasiten die Evolution der Kolonieaggressivität der Wirtsart direkt beeinflussen. Die letztenrnbeiden Publikationen beschäftigten sich mit Sklavenrebellion, einer rätselhaftenrnVerteidigungsstrategie, da noch unklar ist, wie eine Eigenschaft von nicht reproduzierendenrnIndividuen vererbt werden kann. In einer Metaanalyse konnten wir die weite Verbreitung undrnhohe Variabilität dieser Eigenschaft dokumentieren, und fanden Hinweise, dassrnVerwandtenselektion eine mögliche Erklärung für die Evolution dieses Merkmals darstellenrnkönnte.

Estimating Spatial Distribution of American Lobster Homarus Americanus Using Habitat Variables

The spatial distribution of the American lobster Homarus americanus is influenced by many factors, which are often difficult to quantify. We implemented a modeling approach for quantifying season-, size-, and sex-specific lobster spatial distribution in the Gulf of Maine with respect to environmental and spatial variables including bottom temperature, bottom salinity, latitude, longitude, depth, distance offshore, and 2 substratum features. Lobster distribution was strongly associated with temperature and depth, and differed seasonally by sex. In offshore waters in the fall, females were dominant at higher latitudes and males at lower latitudes. This segregation was not apparent in the spring although females were still dominant at higher latitudes in offshore waters. Juveniles and adults were also distributed differently; juveniles were more abundant at the lower latitudes in inshore waters, while adults were more widespread along the entire coast. These patterns are consistent with the ecology of the American lobster. This study provides a tool to evaluate changes in lobster spatial distribution with respect to changes in key habitat and other environmental variables, and consequently could be of value for the management of the American lobster.

Factors Affecting Post-Capture Survivability of Lobster Homarus Americanus

Technological advances in gear and fishing practices have driven the global expansion of the American lobster live seafood market. These changes have had a positive effect on the lobster industry by increasing capture efficiency. However, it is unknown what effect these improved methods will have on the post-capture fitness and survival of lobsters. This project utilized a repeated measures design to compare the physiological changes that occur in lobsters over time as the result of differences in depth, hauling rate, and storage methodology. The results indicate that lobsters destined for long distance transport or temporary storage in pounds undergo physiological disturbance as part of the capture process. These changes are significant over time for total hemocyte counts, crustacean hyperglycemic hormone, L-lactate, ammonia, and glucose. Repeated measures multivariate analysis of variance (MANOVA) for glucose indicates a significant interaction between depth and storage methodology over time for non-survivors. A Gram-negative bacterium, Photobacterium indicum, was identified in pure culture from hemolymph samples of 100% of weak lobsters. Histopathology revealed the presence of Gram-negative bacteria throughout the tissues with evidence of antemortem edema and necrosis suggestive of septicemia. On the basis of these findings, we recommend to the lobster industry that if a reduction in depth and hauling rate is not economically feasible, fishermen should take particular care in handling lobsters and provide them with a recovery period in recirculating seawater prior to land transport. The ecological role of P. indicum is not fully defined at this time. However, it may be an emerging opportunistic pathogen of stressed lobsters. Judicious preemptive antibiotic therapy may be necessary to reduce mortality in susceptible lobsters destined for high-density holding facilities.

Different Early Post-Settlement Strategies Between American Lobsters Homarus Americanus and Rock Crabs Cancer Irroratus in the Gulf of Maine

The abundance of many invertebrates with planktonic larval stages can be determined shortly after they reach the benthos. In this study, we quantified patterns of abundance and habitat utilization of early benthic phases of the American lobster Homarus americanus and the rock crab Cancer irroratus. These 2 decapods are among the most common and abundant macroinvertebrates in coastal zones of the Gulf of Maine, with similar densities of larger individuals. Settlement and early postsettlement survival indicate that lobsters are highly substrate-specific early in life, settling predominantly in cobble beds. Crabs appear to be less selective, setting both in cobble and sand. Cumulative settlement of crabs, inferred from weekly censuses over the summer, was an order of magnitude greater than that of lobsters over the same time period. However, only crabs showed significant postsettlement losses. Although the identity of specific predators is unknown, predator exclusion experiments and placement of vacant uninhabited nursery habitat suggested that post-settlement mortality rather than emigration was responsible for these losses. The selective habitat-seeking behavior and lower post-settlement mortality of lobsters is consistent with their lower fecundity and later onset of reproductive maturity. The patterns observed for crabs, however, suggest a different strategy which is more in accordance with their higher fecundity and earlier onset of maturity. It is possible that lower fecundity but greater per-egg investment, along with strict habitat selection at settlement and lower post-settlement mortality, allows adult lobster populations to equal adult populations of crabs. This occurs despite crabs being more fecund and less habitat-selective settlers but sustaining higher postsettlement mortality.

Kelp Beds as Habitat for American Lobster Homarus Americanus

The American lobster Homarus americanus and kelp Laminaria longicruris and L. saccharina are prominent and often intimately associated members of the subtidal community in the western North Atlantic Ocean. However, no one has identified the nature of this relationship or specifically investigated whether kelp beds are a superior habitat for lobsters. We conducted field studies in 1990 and 1991 at a coastal site centrally located along the Gulf of Maine, USA, to determine how lobsters use kelp beds as habitat. Identically sized and spaced plots of live and artificial (plastic) kelp were established and monitored for lobster population densities. Adjacent featureless sediment plots of identical size served as controls. Lobster population density and biomass were significantly higher in both real and artificial kelp treatments than in non-kelp control plots (p < 0.0001). The change in lobster density was apparent the day following placement of the experiment, so a secondary trophic effect such as attracting prey into treatments is unlikely to have occurred. Thus, kelp beds can affect local lobster population densities by providing shelter for lobsters, thereby concentrating individuals and increasing the local carrying capacity of potential lobster habitats. The effect of kelp beds on the local carrying capacity of lobster habitats was further explored by testing how lobsters respond to differing patch sizes. A graded size series of circular patches of artificial kelp was established, in which kelp blade density and total area were held constant for each treatment. Treatments were subdivided into four 1 M2, two 2 M2, or one 4 m2 patches. Experiments were surveyed for lobster population density and size structure to determine ff statistical differences existed among treatments. Lobster density was significantly greater in the smallest patches (p < 0.001). Moreover, lobsters typically occupied the edges of kelp beds, and their abundance within kelp patches corresponded to the patch's perimeter-to-area relationship. This suggests that edge effects' influence the local carrying capacity for lobsters by influencing the lobsters' choice of kelp beds as habitat.

Recruitment Habitats and Nursery Grounds of the American Lobster Homarus Americanus: A Demographic Bottleneck?

We have identified benthic recruitment habitats and nursery grounds of the American lobster Homarus americanus Milne Edwards in the coastal Gulf of Maine, USA, by systematically censusing subtidal sediment, cobble, and ledge substrata. We distinguish lobsters between settlement size (5 mm carapace length (CL) to ca 40 mm CL as the 'early benthic phase' (EBP) because they are ecologically and behaviorally distinct from larger lobsters. EBP lobsters are cryptic and apparently restricted to shelter-providing habitats (primarily cobble substratum) in coastal Gulf of Maine. In these habitats we found average population densities of EBP lobsters as high as 6.9 m-2. EBP lobsters were virtually absent from ledge and sedimentary substrata devoid of vegetation although larger lobsters are commonly found there. It is possible that the requirement for shelter-providing substrata by this life phase creates a natural demographic 'bottleneck' to benthic recruitment for the species. Prime cobble recruitment habitat is relatively rare and comprises ca 11 % of the 60.2 km of shoreline at our study area in midcoast Maine. If this low availability of cobble exists throughout the Gulf of Maine, as other studies indicate, it could limit lobster production potential. We verified the geographic extent of recruitment to cobble habitats censused in 3 of 4 regions spanning ca 300 km of the coastal Gulf of Maine (from Nahant, Massachusetts to Swans Island, Maine). Early benthic phase lobsters were absent from cobble censused in the northeastern extreme of our survey (Swans Island). This pattern is consistent with earlier speculation that relatively cool water temperatures may limit larval settlement in this region.