Molting Activity Research Articles

Multiple-Rusophycus assemblage from the Parnaíba Basin (NE Brazil) reflects trilobites as tracemakers and molting behavior

Trilobites inhabited all environments of Paleozoic seas, ranging from estuaries to continental slopes, and were globally distributed. Although their functional morphology and phylogenetic relations are established by well-preserved body fossils, the behavior of trilobites has received less attention. Three well-known trace fossils are interpreted to be produced by trilobitomorphs when preserved in Paleozoic rocks, Rusophycus (a resting trace), Cruziana (a furrowing trace), and Diplichnites (a locomotion trace). Those trace fossils unveil some aspects of trilobite behavior, but they were not investigated to test paleoecologic strategies based on morphometric parameters. This study uses Rusophycus to access the paleoecologic strategies of trilobites in storm-dominated shallow marine deposits of the Pimenteira and Cabeças formations (Middle to Upper Devonian, Parnaíba Basin, Brazil). It was conducted a detailed analysis of the Rusophycus specimens in a section that represents the transition between the Pimenteira and Cabeças formations (Parnaíba Basin). The width and length of the Rusophycus were measured, and statistical analyses were performed to understand the population characteristics. Relatively small-sized Rusophycus are dominant in such deposits, suggesting the dominance of young tracemakers and inferred r-strategist populations. The here reported multiple-Rusophycus assemblage reveals paleoecologic strategies of the population, and tiers relationship (cross-cutting epistratal and shallow-tier trace fossils such as Bergaueria, Palaeophycus, and Protopaleodictyon) indicate deep Rusophycus. The main reason for those burrowing activities deep in the substrate might be protection during ecdysis. Thus, the random distribution, lack of hunting evidence, and depth of Rusophycus suggest molting activity as the trigger for their production in storm-influenced beds of the Pimenteira Formation, probably by calmoniids or homalonotids.

Molting, tissue calcium‑phosphorus deposition and immunity of juvenile Chinese mitten crab (Eriocheir sinensis) fed different levels of calcium and vitamin D3

Molting activity and innate immunity play a pivotal role in the development and growth of crustaceans and are related to mortality and body abnormality. To evaluate the synergistic effect of vitamin D3 (vit-D3) and Ca in molting and immunity in Chinese mitten crab (Eriocheir sinensis), the crabs (3.20 ± 0.01 g) were fed six diets formulated with two Ca levels (0% and 1.5%, abbreviated D and N) and three vit-D3 levels (0, 9,000 and 27,000 IU/kg, abbreviated LVD, MVD and HVD) level for 56 days. Crabs fed 1.5% Ca and 9,000 IU/kg vit-D3 (N + MVD) had the highest growth performance, hematic-1,25-dihydroxy vit-D3, hematic‑calcium, hepatic‑phosphorus and antioxidant capacity among all groups. On the contrary, crabs fed diets without Ca reduced growth performance, tissue calcium‑phosphorus deposition, antioxidant capacity, and the expression of molting-related and immune-related genes. Compared to crab fed N + HVD (1.5% Ca + 27,000 IU/kg vit-D3), those fed D + HVD (0% Ca +27,000 IU/kg vit-D3) had significantly low growth performance and the gene expressions of molting and antibacterial immunity. This study demonstrates that adequate dietary calcium and vit-D3 can enhance growth, molting activity, antioxidant capacity and innate immunity in E. sinensis. Moreover, it provides an in-depth understanding of the molecular mechanism of molting activity and antibacterial immunity in Chinese mitten crab

Chronic effects of the strobilurin fungicide azoxystrobin in the leaf shredder Gammarus fossarum (Crustacea; Amphipoda) via two effect pathways

Fungicides pose a risk for crustacean leaf shredders serving as key-stone species for leaf litter breakdown in detritus-based stream ecosystems. However, little is known about the impact of strobilurin fungicides on shredders, even though they are presumed to be the most hazardous fungicide class for aquafauna. Therefore, we assessed the impact of the strobilurin azoxystrobin (AZO) on the survival, energy processing (leaf consumption and feces production), somatic growth (growth rate and molting activity), and energy reserves (neutral lipid fatty and amino acids) of the amphipod crustacean Gammarus fossarum via waterborne exposure and food quality-mediated (through the impact of leaf colonizing aquatic microorganisms) and thus indirect effects using 2 × 2-factorial experiments over 24 days. In a first bioassay with 30 µg AZO/L, waterborne exposure substantially reduced survival, energy processing and affected molting activity of gammarids, while no effects were observed via the dietary pathway. Furthermore, a negative growth rate (indicating a body mass loss in gammarids) was induced by waterborne exposure, which cannot be explained by a loss in neutral lipid fatty and amino acids. These energy reserves were increased indicating a disruption of the energy metabolism in G. fossarum caused by AZO. Contrary to the first bioassay, no waterborne AZO effects were observed during a second experiment with 15 µg AZO/L. However, an altered energy processing was determined in gammarids fed with leaves microbially colonized in the presence of AZO, which was probably caused by fungicide-induced effects on the microbial decomposition efficiency ultimately resulting in a lower food quality. The results of the present study show that diet-related strobilurin effects can occur at concentrations below those inducing waterborne toxicity. However, the latter seems to be more relevant at higher fungicide concentrations.

Effects of breeding and molt activity on songbird site fidelity

AbstractThe prebasic molt is a perilous period for songbirds, characterized by heightened energetic demands and vulnerability to predators. Given these vulnerabilities, songbirds are under selective pressure to locate and use quality habitat during the prebasic molt, potentially resulting in site fidelity between years. In this study, we aimed to determine how differences in breeding and molting activity affected site fidelity for a diversity of species at the landscape scale. To accomplish our objective, we used 31 yr of banding data from northern California and southern Oregon for 16 species of songbirds with Cormack-Jolly-Seber analyses and weighted linear regression models to assess the effects of molting and breeding activity on the probability of a species returning to a site in subsequent years. Despite substantial variation in site use for breeding and/or molting, each study species had at least some locations that were used for both breeding and molting. Captured breeding birds (n = 18,574) were much more common than molting birds (n = 7,622). Breeding activity was positively correlated with higher site fidelity for 10 of the 16 species, while we found little evidence of a relationship between molting activity and site fidelity. Only the Dark-eyed Junco (Junco hyemalis) showed increased site fidelity with increased presence of molt activity. It is likely that a shifting mosaic of food resources during the post-breeding period drives dynamic movements of songbirds in search of the necessary resources to successfully complete their annual molt.

A Comparative Study on Growth and Metabolism of Eriocheir sinensis Juveniles Under Chronically Low and High pH Stress

This study elucidates the effects of chronic pH stress on the growth and metabolic response of juvenile Chinese mitten crab Eriocheir sinensis. Crabs were exposed under normal pH (control, pH = 8.0 ± 0.20), low pH (pH = 6.5 ± 0.20), and high pH (pH = 9.5 ± 0.20) in an 8-week trial. Both low and high pH suppressed weight gain but low pH had more adverse effects. No difference was observed on survival, crude lipid, and protein. Acidic stress significantly reduced protein efficiency. The malondialdehyde (MDA) content in hepatopancreas was highest at low pH. The superoxide dismutase (SOD) activity in hepatopancreas and total hemocyte counts (THC) in the stress groups were higher than that in the control. Crabs under high pH had the highest ACP and AKP activities, but there was no significant difference between the control and low pH groups. In the transcriptome analysis, 500.0M clean reads were obtained from the control, low pH, and high pH groups, and assembled into 83,025 transcripts. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were analyzed to obtain the significantly changed pathways involving differently expressed genes. Ten and eight pathways in metabolism were significantly changed in low pH vs control and high pH vs control groups, respectively. According to the reported functions of these pathways, most of them participated in carbohydrate metabolism. The metabolism pathway analysis indicates the increases of stress resistance, glucose metabolism, and molting activities under chronically pH stress. This study suggests that low pH has more negative impact on crab growth, and oxidative phosphorylation is the main source of energy source under low pH stress, while aerobic glycolysis supplies most energy under high pH stress.

Molecular cloning, characterization and gene expression analysis of aminolevulinic acid synthase in Litopenaeus vannamei

5-Aminolevulinic acid synthase (ALAS) is the rate-limiting enzyme in the biosynthesis of heme, a prosthetic group that is found in hemoproteins, including those involved in molting. To better understand the roles of ALAS in L. vannamei (LvALAS), we analyzed its sequence and tissue distribution, the effects of age and bacterial infection on its gene expression, and the effects of LvALAS gene silencing. We also examined the expressions of three hemoproteins, the cytochrome oxidase subunit I (COX I) and subunit IV (COX IV) and catalase. Three LvALAS splicing variants were found in the hepatopancreas, with the main splicing variant having an open reading frame that encodes 532 aa. LvALAS transcripts were found in each of the eleven tissues tested in this study, with the highest gene expression in the intestine. The transcript abundances of LvALAS, COX I and COX IV in the hepatopancreas and stomach tended to decrease with age. LvALAS and catalase gene expressions significantly increased in the stomach after V. parahaemolyticus infection. LvALAS gene expression in the hepatopancreas, stomach and intestine (12- and 24-hours post-injection) was relatively lower in dsALAS-injected shrimp than in PBS-injected shrimp. All the PBS-injected shrimp molted after 8–10 days while no molting activity was observed in the dsALAS-injected shrimp group within the 14 days post-injection period. Our results provide evidence that (1) only the housekeeping form of ALAS exists in L. vannamei; LvALAS gene expression (2) decreases with age and (3) increases after bacterial infection; and (4) an ALAS-dependent pathway is necessary for proper molting in L. vannamei.

Growth of juvenile southern king crabs (Lithodes santolla) in San Jorge Gulf, Southwestern Atlantic Ocean

The southern king crab (SKC), Lithodes santolla, supports a lucrative fishery in San Jorge Gulf (SJG), Argentina and its adjacent area in the southwestern Atlantic Ocean. However, despite its commercial value, biological data on the SKC in SJG are scarce. In this study, we analyzed the growth of early juvenile SKCs by combining field and laboratory data. Sampling was carried out monthly in shallow waters in the central area of SJG (44°–46 °S). The sex and molt stages of SKC were recorded and the carapace length (CL) was measured. Individuals in premolt were taken alive to the laboratory to measure the molt increment. Size frequency distribution was used to assess modal progression, whereas the molt increments determined in the laboratory were used to verify the modal groups identified. Juvenile SKCs had molting activity throughout the year with no synchronization of the molt cycle observed. The molt increment ranged from 0.37 to 8.86 mm and the relative increment varied between 7.13 and 48.29 %. A total of 17 post-settlement modal groups were recognized: nine within the first year post-settlement, four within the second and three within the third. A wide variability in CL was recorded within the same annual class, which could be due to the absence of molting synchrony and the wide range of molt increment. Our results suggest that both male and female SKCs reach maturity four and a half years after settlement and that males recruit to the fishery seven years after settlement (at 110 mm CL).

Heavy metals effects on life traits of juveniles of <em>Procambarus clarkii</em>

An incubation experiment of juvenile crayfish (Procambarus clarkii) following a three- level treatment design approach was performed to assess the effect of different heavy metal concentrations on their life history traits (lifespan, growth, moult and feeding activity). The aims were to: (1) address the response of the life traits; (2) check for the correlation between heavy metal concentrations in crayfish whole bodies with the ones of the experimental solutions; (3) analyse the variation of crayfish carbon and nitrogen stable isotopes signatures grown under these treatments. Treatments were: control or absence of pollutants (C); low level contamination (L) similar to those found in the water of the Guadiamar River (SW, Spain) one year after the Aznalcollar mine accident, and high level contamination (H) maximum concentrations of metals measured in the water of the river after the spill. The study concludes that the H treatment produced lethal effects on juveniles of crayfish, whereas those undergoing the L treatment showed less marked effects. Crayfish’s juveniles grown in L treatment seemed able to regulate and manage this range of pollution while maintaining their biological traits. Juvenile’s capacity to bioaccumulate toxic substances also changes with the nature of the particular metals. The reduction in lifespan was mainly influenced by Cu, Zn and As. 13 C of C and juveniles from L treatment had similar values but different from those individuals of H treatment, reflecting the isotopic signature of the food source used (liver), and were also influenced by the concentration of Cu and As.

Seasonality at the equator: isotope signatures and hormonal correlates of molt phenology in a non-migratory Amazonian songbird

BackgroundBirds, across their annual cycle, progress through sequences of life-history stages such as reproduction and molt. The mechanisms that control annual avian itineraries involve endocrine responses triggered by seasonal environmental factors, including changes in resource availability and/or photoperiod. However, at equatorial latitudes birds are exposed to different degrees of seasonality, and the mechanisms underlying phenology of birds near the equator remain less explored. We studied the silver-beaked tanager, an endemic Amazonian songbird, from an equatorial lowland population. Remarkably, in this species, song behavior has been shown to be seasonally aligned to minimal changes in day length near the equator. Here, we aimed to further explore the phenology of silver-beaked tanagers by assessing shifts of food sources utilization as potential ultimate factors. We measured triple isotopic tracers of carbon (δ13C), nitrogen (δ15N) and sulphur (δ34S) in blood and feathers of birds throughout a whole year. In addition, we assessed the degree of seasonality in the molting activity, in relation to circulating levels of corticosterone, as well as to testosterone as a proxy of the reproductive condition of males.ResultsThere was important seasonal variation of δ34S values in relation to rainfall patterns and changes in estuarine water composition. Despite the seasonal rainfall, we found no substantial variation in the foraging ecology of birds over seasons. This was accompanied by uniform levels of corticosterone throughout the year, probably associated with the absence of drastic seasonal resource shortages. Even so, silver-beaked tanagers showed a marked seasonal molting schedule, which was related to variation in the circulating levels of both corticosterone and testosterone.ConclusionsThese findings suggest that foraging niche is not life history stage-dependent in silver-beaked tanagers, and highlight rainfall as an important environmental cue for bird phenology. Our stable isotope results encourage further studies addressing the influence of estuarine water dynamics on bird timing. In addition, the results suggest a primary role of steroid hormones in regulating seasonal life history stages under the absence of a marked photoperiod. Contrary to what might be expected for a tropical songbird, our physiological data in silver-beaked tanagers do not support reproduction-molt overlapping.

Characterization of candidate intermediates in the Black Box of the ecdysone biosynthetic pathway in Drosophila melanogaster: Evaluation of molting activities on ecdysteroid-defective larvae

Early steps of the biosynthetic pathway of the insect steroid hormone ecdysone remains the “Black Box” wherein the characteristic ecdysteroid skeleton is built. 7-Dehydrocholesterol (7dC) is the precursor of uncharacterized intermediates in the Black Box. The oxidation step at C-3 has been hypothesized during conversion from 7dC to 3-oxo-2,22,25-trideoxyecdysone, yet 3-dehydroecdysone is undetectable in some insect species. Therefore, we first confirmed that the oxidation at C-3 occurs in the fruitfly, Drosophila melanogaster using deuterium-labeled cholesterol. We next investigated the molting activities of candidate intermediates, including oxidative products of 7dC, by feeding-rescue experiments for Drosophila larvae in which an expression level of a biosynthetic enzyme was knocked down by the RNAi technique. We found that the administration of cholesta-4,7-dien-3-one (3-oxo-Δ4,7C) could overcome the molting arrest of ecdysteroid-defective larvae in which the expression level of neverland was reduced. However, feeding 3-oxo-Δ4,7C to larvae in which the expression levels of shroud and Cyp6t3 were reduced inhibited molting at the first instar stage, suggesting that this steroid could be converted into an ecdysteroid-antagonist in loss of function studies of these biosynthetic enzymes. Administration of the highly conjugated cholesta-4,6,8(14)-trien-3-one, oxidized from 3-oxo-Δ4,7C, did not trigger molting of ecdysteroid-defective larvae. These results suggest that an oxidative product derived from 7dC is converted into ecdysteroids without the formation of this stable conjugated compound. We further found that the 14α-hydroxyl moiety of Δ4-steroids is required to overcome the molting arrest of larvae in loss of function studies of Neverland, Shroud, CYP6T3 or Spookier, suggesting that oxidation at C-14 is indispensable for conversion of these Δ4-steroids into ecdysteroids via 5β-reduction.

Postecdysis Sclerotization of Mouthparts of the Formosan Subterranean Termites (Isoptera: Rhinotermitidae).

In termites, it is challenging to recognize the incidence of molting in workers because of their successive stationary molt, asynchronous molting among individuals, cryptic behavior, a soft and poorly sclerotized cuticle, and they immediately consume the shed exuvia of nestmates. This study describes a method in which the degree of sclerotization of the mouthparts in newly molted workers of the Formosan subterranean termite can be quantified and used to determine if an individual has recently molted, within a 36-h time frame. Changes in the tanning of mouthparts over time were used as a measure of the index of sclerotization in workers postmolting. Upon ecdysis, the primary point of articulation of the mandible already initiated sclerotization, which may allow the movement of the mandibles during the shedding of the exuvium. The sclerotization of the secondary point of articulation and the mandibular teeth, and the width of sclerotization of the mandibles, progressively increased until reaching a plateau around 36-h postecdysis, which imply that workers can regain some level of activity as early as 2 d after ecdysis. Our observations allowed for the determination of variables for the sclerotization of the mouthparts to easily identify workers that recently molted, and this method will be useful in future studies that focus on the molting activity of workers over time and space within a termite colony, in the scope of improving current control strategies for termite pests.

Life in the sea of plenty: Seasonal and regional comparison of physiological performance of Euphausia hanseni in the northern Benguela upwelling system

Variability in upwelling events may lead to periods of constrained food availability in the northern Benguela upwelling system (NBUS), thereby affecting the physiological state and metabolic activity of euphausiids. Most attention has so far been paid to seasonal effects but little is known about regional variability. Metabolic activity (expressed by respiration and excretion rates) and physiological state (expressed by reproductive effort and moult activity) in Euphausia hanseni were examined at different stations during austral summer (minimum upwelling) and austral winter (maximum upwelling). Overall, regional differences in physiological state, influencing metabolic activity, were greater than seasonal ones, indicating favourable conditions for growth and reproduction year-round. Higher respiration rates were found for females in more advanced stages of sexual development. Moult stage did not affect oxygen consumption rates, however. The physiological state of E. hanseni at the time of capture may serve as a meaningful indicator of the associated hydrographic conditions in the NBUS, to be further used in eco-system analysis on seasonal or long-term time scales. A latitudinal comparison of species highlights the extraordinary physiological plasticity of euphausiids.

Seasonal change in molting activity of juvenile beni-zuwai crab Chionoecetes japonicus revealed by a rearing experiment using deep-sea water

Seasonal change in molting activity of juvenile beni-zuwai crab Chionoecetes japonicus revealed by a rearing experiment using deep-sea water

Adaptive Molting Signal in a Gregarious Sawfly Larva, Perga affinis?

For any arthropod, molting is a risky endeavor; it leaves an organism vulnerable until its new cuticle hardens. In some social organisms, the safest place for an individual to molt may be within their group. Here I present preliminary observations of a potential signaling behavior associated with molting in the gregarious larvae of the Australian sawfly, Perga affinis. Observations of molting activity revealed that larvae were significantly more likely to molt during the day, while residing in tight clusters, than at night when they were dispersed. Additionally, on two occasions I witnessed a vibrational and tactile behavior given by a larva 30 min prior to ecdysis. In each case, this behavior affected the other group members by delaying dispersal for foraging until the molting individual finished ecdysis; this change in the group’s behavior suggests that the molting larva engaged in a form of communication. Potential benefits for a molting signal are discussed.

Decreased level of crustacean hyperglycemic hormone (CHH) in black tiger shrimp Penaeus monodon suffering from Monodon Slow-Growth Syndrome (MSGS)

Monodon Slow-Growth Syndrome (MSGS), a pathological condition in the black tiger shrimp Penaeus monodon, is associated with Laem–Singh virus (LSNV) infection. Infected shrimp grow slowly when the virus invades the part of the retina called the zona fasciculata. Since molt-inhibiting hormone (MIH) and crustacean hyperglycemic hormone (CHH) are synthesized in the optic lobe and are related to molting activity and growth of the shrimp, the purpose of this study is therefore to determine the levels of these hormones and related parameters in MSGS shrimp. P. monodon juveniles were sampled from normal and MSGS ponds and were divided into small-negative, large-negative, small-positive and large-positive groups, depending on the size of the shrimp and whether they were LSNV-negative or LSNV-positive. Individual shrimp were measured for duration of each molt stage and molt interval. Levels of MIH1 and CHH1 transcripts were determined from the optic lobe, using real-time reverse transcriptase–polymerase chain reaction. The results revealed that the small-positive and the small-negative shrimp did not differ in durations of molt stages or molt intervals, as well as on the levels of MIH1 transcript in the optic lobe, MIH1 peptide in the optic lobe and hemolymph, or ecdysteroids in the hemolymph. Differences in molting activities and related transcript and hormones were observed between the small- and large-sized shrimp, but not in the status of LSNV infection. While levels of CHH1 transcript in the optic lobe of both small-negative and small-positive shrimp did not differ, levels of CHH1 peptide, as well glucose, in the hemolymph of the small-positive shrimp were significantly lower than those of the small-negative group. Levels of glycogen in the hepatopancreas of the small-positive shrimp were also significantly higher than that of the small-negative ones. The results suggest that growth retardation in MSGS shrimp is related to the suppression of the release of CHH1 peptide by LSNV invasion in the zona fasciculata, consequently causing decreased hepatopancreatic glycogenolysis and persistent hypoglycemia, resulting in growth stunting.

Epidemiological determinants in outbreaks of bitter crab disease (Hematodinium sp.) in snow crabs Chionoecetes opilio from Conception Bay, Newfoundland, Canada

Bitter crab disease (BCD) is caused by Hematodinium sp., an endoparasitic dinoflagellate. It lives within the hemocoeloms of snow crabs Chionoecetes opilio and Tanner crabs C. bairdi, making them unmarketable due to their bitter flavor. Two recent outbreaks of BCD have occurred in Conception Bay, Newfoundland, one from 1999 to 2000 and another from 2003 to 2005. In the earlier outbreak, prevalence was highest in juvenile and primiparous females and juvenile males. It was thought to be highest in these hosts because they molt more frequently than larger males and the disease is transmitted to newly molted crabs. In the 2003 to 2005 outbreak, the prevalence of BCD changed and was at its highest, 24% in trapped males and 13.5% in trawled males. This apparent shift in the dynamics of the infection between the earlier 1999 to 2000 and later 2003 to 2005 outbreaks was highly correlated with 2 factors: an increase in bottom temperatures, associated with the recent climatic warming trend in the Northwest Atlantic, and an increase in molting activity of the snow crabs due presumably to the temperature increase within Conception Bay. That is, rising temperatures occurring from 2003 to 2005 likely stimulated molting activity in snow crabs, which led to an increase in susceptible hosts in the population. Given the positive correlation between increased bottom temperature, increased molting activity, and the latest outbreak of BCD, we predict that further trends in climatic warming will enhance transmission, spreading the parasite into additional fishing areas.

Plumage Development and Molt in Long-Tailed Manakins (Chiroxiphia Linearis): Variation According to Sex and Age

AbstractLek-mating Long-tailed Manakins (Chiroxiphia linearis) exhibit an unusual pattern of delayed plumage maturation. Each year, males progress through a series of predefinitive plumages before attaining definitive plumage in their fifth calendar year. Females also exhibit variation in plumage coloration, with some females displaying male-like plumage characteristics. Using data from mist-net captures in northwest Costa Rica (n = 1,315) and museum specimens from throughout the range of Long-tailed Manakins (n = 585), we documented the plumage sequence progression of males, explored variation in female plumage, and described the timing of molt in this species. Males progressed through a series of age-specific predefinitive plumages, which enabled the accurate aging of predefinitive-plumaged males in the field; this predefinitive plumage sequence is the basis for age-related status-signaling in these males. Females tended to acquire red coloration in the crown as they aged. However, colorful plumage in females may be a byproduct of selection on bright male plumage. Females exhibited an early peak of molt activity from February to April, little molt from May through July, and a second, more pronounced peak of molt activity in October. By contrast, males in older predefinitive-plumage stages and males in definitive plumage exhibited comparable unimodal distributions in molt activity beginning in June and peaking between July and October. Our data are consistent with selective pressure to avoid the costs of molt-breeding overlap in females and older males. Our findings have important implications for social organization and signaling in Long- tailed Manakins, and for the evolution of delayed plumage maturation in birds.Desarrollo del Plumaje y Muda en Chiroxiphia linearis: Variación de Acuerdo al Sexo y la Edad

PLUMAGE DEVELOPMENT AND MOLT IN LONG-TAILED MANAKINS (CHIROXIPHIA LINEARIS): VARIATION ACCORDING TO SEX AND AGE

Lek-mating Long-tailed Manakins (Chiroxiphia linearis) exhibit an unusual pattern of delayed plumage maturation. Each year, males progress through a series of predefinitive plumages before attaining definitive plumage in their fifth calendar year. Females also exhibit variation in plumage coloration, with some females displaying male-like plumage characteristics. Using data from mist-net captures in northwest Costa Rica (n = 1,315) and museum specimens from throughout the range of Long-tailed Manakins (n = 585), we documented the plumage sequence progression of males, explored variation in female plumage, and described the timing of molt in this species. Males progressed through a series of age-specific predefinitive plumages, which enabled the accurate aging of predefinitive-plumaged males in the field; this predefinitive plumage sequence is the basis for age-related status-signaling in these males. Females tended to acquire red coloration in the crown as they aged. However, colorful plumage in females may be a byproduct of selection on bright male plumage. Females exhibited an early peak of molt activity from February to April, little molt from May through July, and a second, more pronounced peak of molt activity in October. By contrast, males in older predefinitive-plumage stages and males in definitive plumage exhibited comparable unimodal distributions in molt activity beginning in June and peaking between July and October. Our data are consistent with selective pressure to avoid the costs of molt-breeding overlap in females and older males. Our findings have important implications for social organization and signaling in Long- tailed Manakins, and for the evolution of delayed plumage maturation in birds. Desarrollo del Plumaje y Muda en Chiroxiphia linearis: Variación de Acuerdo al Sexo y la Edad

Stereoselective synthesis and moulting activity of integristerone A and analogues

Integristerone A, a rare ecdysteroid of plant origin, has been synthesized from 20-hydroxyecdysone with 2-deoxy-1,2-didehydro-20-hydroxyecdysone as the key intermediate, followed by stereoselective asymmetric dihydroxylation. The analogues 1,2-di- epi-integristerone A and 1,2-di- epi-5α-integristerone A have also been synthesized. Integristerone A exhibited approximately 9-fold lower moulting activity than the parent 20-hydroxyecdysone in the Musca domestica bioassay, indicating that the presence of a 1β-hydroxyl group resulted in a decrease in activity. As expected, the 1,2-di- epi-5α-analogue was inactive in this assay.

Ciclo reprodutivo do caranguejo violinista Uca rapax (Smith) (Crustacea, Brachyura, Ocypodidae) habitante de um estuário degradado em Paraty, Rio de Janeiro, Brasil

Este trabalho descreve o ciclo reprodutivo de Uca rapax (Smith, 1870) baseado em observações do seu desenvolvimento gonadal e ciclo de muda em uma área de manguezal degradado em Paraty, Estado do Rio de Janeiro. Os caranguejos foram capturados por duas pessoas mensalmente (julho/2001 a junho/2002) durante 15 minutos por meio da técnica de esforço de captura em período de maré baixa. No laboratório, os caranguejos foram mensurados quanto à largura da carapaça (LC); sendo o sexo, a condição ovígera e o estágio gonadal anotados. Os estágios de desenvolvimento gonadal foram determinados por meio da observação macroscópica das gônadas e os estágios de muda através da observação do grau de enrijecimento do tegumento. Os caranguejos que apresentavam gônadas imaturas e rudimentares foram considerados imaturos enquanto os demais estágios gonadais, maduros. Obteve-se um total de 1558 espécimes, sendo 801 machos e 757 fêmeas (16 fêmeas ovígeras). As fêmeas ovígeras representaram apenas 3% da população, talvez pelo fato destas fêmeas permanecerem em suas tocas. Apesar de terem sido encontrados caranguejos com gônadas maduras ao longo de todo o ano, o período de maior atividade reprodutiva em U. rapax ocorre nos meses mais quentes do ano (primavera-verão). A freqüência de caranguejos em atividade de muda ao longo do período de estudo foi baixa (12,8%) em relação aos caranguejos em intermuda. Provavelmente, U. rapax permaneça entocada nesse período crítico, que é a troca do exoesqueleto. Apesar de U.rapax ocorrer em um manguezal completamente degradado, o seu ciclo reprodutivo não foi afetado, quando comparado com de áreas não degradadas estudadas anteriormente. Tal fato pode ser sustentado pela presença de caranguejos potencialmente maduros ao longo do ano todo na área de estudo.