Yeast phosphoglycerate mutate. Cyanogen bromide cleavage and amino acid sequence of an active-site peptide.

The molecular weight and amino acid composition of phosphoglycerate mutase from yeast were determined. CNBr cleavage produced a large (190-residue) fragment and a small (60-residue) fragment. Tryptic and chymotryptic peptides derived from the large fragment were fractionated by ion-exchange chromatography. Peptides from two histidine-containing regions were isolated and the amino acid sequences were determined. Correlation of these data with X-ray-crystallographic evidence shows that the histidine residue in the sequence Arg-Leu Asn-Glu-Arg-His-Tyr-Gly-Asp-Leu-Glu-Gly-Lys is located at the active site.     

Formation of three-dimensional structure in protein fragments. Reactivation of reduced hen egg lysozyme fragment 1-127.

Regeneration of enzymic activity from reduced hen egg lysozyme peptide 1-127 was effected with a glutathione oxidation-reduction buffer. The rate of regeneration was nearly as great for peptide 1-127 as for reduced lysozyme itself, and the yields were the same (greater than 80%). The regenerated fragment 1-127 was shown to be indistinguishable from fragment 1-127 before reduction by ion exchange chromatography, amino acid analysis, polyacrylamide gel electrophoresis, and disulfide analysis. These results show that the COOH-terminal dipeptide Arg-Leu is not essential for the acquisition of the native three-dimensional structure of lysozyme.     

Solid-state conformation of some basic sequential polypeptides

We have studied the structure of solid films obtained by x-ray diffraction, from several basic polypeptides with a defined sequence. The alterating polypeptides poly(Ala-Lys), poly(Leu-Lys), poly(Val-Lys), and poly(Arg-Leu) all show a cross-β-structure in which layers of hydrophilic side chains alternate with layers containing hydrophobic side chains. The other polypeptides studied are not in the β-conformation and appear to be in the α-helical conformation. The helices obtained from poly(Lys-Ala-Ala) and poly(Lys-Ala-Ala-Lys) appear to be packed in an unusual fashion, which favors interaction between alanine side chains. Such behavior is not found in poly(Lys-Leu-Ala).     

Augmentation and evaluation of a parasitoid,Encarsia inaron,and a predator,Clitostethus arcuatus,for biological control of the pomegranate whitefly,Siphoninus phillyreae

The aim of this study was to evaluate the biological control potential of Encarsia inaron (Walker) (Hymenoptera: Aphelinidae) and a predator Clitostethus arcuatus (Rossi) (Coleoptera: Coccinellidae) against the pomegranate whitefly, Siphoninus phillyreae (Haliday) (Homoptera: Aleyrodidae) on pomegranate (Punica granatum L.) by mass rearing and augmentative releases of these two natural enemies during a long-term field study in Egypt. A study was conducted to evaluate the biological control potential of this pest by augmentation with a parasitoid, En. inaron, and a predator, C. arcuatus. Both species were mass reared and monthly releases were made in fields of pomegranate during each of 11 consecutive years (1996–2006). About 1,155,000 En. inaron and 990,000 C. arcuatus were released in fields in Assuit governorate in Egypt on pomegranate which was naturally infested by S. phillyreae. Populations of the natural enemies and parasitism were much higher in field plots where releases were made compared with where no releases were made. The maximum rate of parasitism reached 93% (88% by En. inaron) in the field treatment where releases were made, while parasitism peaked at 36% where no releases were made. The population of En. inaron was significantly correlated with the population of whitefly during the field season. Additional parasitism was by natural infestation with Eretmocerus parasiphonini Evans and Abd-Rabou (Hyneoptera: Aphelinidae). Among all years, the maximum number of C. arcuatus ranged from 13 to 44 beetles per 100 leaves for the treatment, and there were more predators in the release plot than in the control plot. These observations enhance understanding of the usefulness of these natural enemies after augmentation in the field.     

Resistin,Adiponectin, Ghrelin,Leptin, and Proinflammatory Cytokines: Relationships in Obesity

Objective: To evaluate interactions among leptin, adiponectin, resistin, ghrelin, and proinflammatory cytokines [tumor necrosis factor receptors (TNFRs), interleukin‐6 (IL‐6)] in nonmorbid and morbid obesity. Research Methods and Procedures: We measured these hormones by immunoenzyme or radiometric assays in 117 nonmorbid and 57 morbidly obese patients, and in a subgroup of 34 morbidly obese patients before and 6 months after gastric bypass surgery. Insulin resistance by homeostasis model assessment, lipid profile, and anthropometrical measurements were also performed in all patients. Results: Average plasma lipids in morbidly obese patients were elevated. IL‐6, leptin, adiponectin, and resistin were increased and ghrelin was decreased in morbidly obese compared with nonmorbidly obese subjects. After adjusting for age, gender, and BMI in nonmorbidly obese, adiponectin was positively associated with HDLc and gender and negatively with weight (β = ?0.38, p < 0.001). Leptin and resistin correlated positively with soluble tumor necrosis factor receptor (sTNFR) 1 (β = 0.24, p = 0.01 and β = 0.28, p = 0.007). In the morbidly obese patients, resistin and ghrelin were positively associated with sTNFR2 (β = 0.39, p = 0.008 and β = 0.39, p = 0.01). In the surgically treated morbidly obese group, body weight decreased significantly and was best predicted by resistin concentrations before surgery (β = 0.45, p = 0.024). Plasma lipids, insulin resistance, leptin, sTNFR1, and IL‐6 decreased and adiponectin and ghrelin increased significantly. Insulin resistance improved after weight loss and correlated with high adiponectin levels. Discussion: TNFα receptors were involved in the regulatory endocrine system of body adiposity independently of leptin and resistin axis in nonmorbidly obese patients. Our results suggest coordinated roles of adiponectin, resistin, and ghrelin in the modulation of the obesity proinflammatory environment and that resistin levels before surgery treatment are predictive of the extent of weight loss after bypass surgery.     

Comparative biology of Portia africana,P. albimana,P. fimbriata,P. labiata,and P. shultzi,araneophagic, web-building jumping spiders (Araneae: Salticidae): Utilisation of webs,predatory versatility,and intraspecific interactions

Abstract

Portia is a behaviourally complex and aberrant salticid genus. The genus is of unusual importance because it is morphologically primitive. Five species were studied in nature (Australia, Kenya, Malaysia, Sri Lanka) and in the laboratory in an effort to clarify the origins of the salticids and of their unique, complex eyes. All the species of Portia studied were both web builders and cursorial. Portia was also an araneophagic web invader, and it was a highly effective predator on diverse types of alien webs. Portia was an aggressive mimic, using a complex repertoire of vibratory behaviour to deceive the host spiders on which it fed. The venom of Portia was unusually potent to other spiders; its easily autotomised legs may have helped Portia escape if attacked by its frequently dangerous prey. Portia was also kleptoparasitic and oophagic when occupying alien webs. P. fimbriata from Queensland, where cursorial salticids were superabundant, used a unique manner of stalking and capturing other salticids. The display repertoires used during intraspecific interactions were complex and varied between species. Both visual (typical of other salticids) and vibratory (typical of other web spiders) displays were used. Portia copulated both on and away from webs and frequently with the female hanging from a dragline. Males cohabited with subadult females on webs, mating after the female matured. Adult and subadult females sometimes used specialised predatory attacks against courting or mating males. Sperm induction in Portia was similar to that in other cursorial spiders. Portia mimicked detritus in shape and colour, and its slow, mechanical locomotion preserved concealment. Portia occasionally used a special defensive behaviour (wild leaping) if disturbed by a potential predator. Two types of webs were spun by all species (Type 1, small resting platforms; Type 2, large prey-capture webs). Two types of egg sacs were made, both of which were highly aberrant for a salticid. Responses of different species and both sexes of Portia were quantitatively compared for different types of prey. Many of the trends in behaviour within the genus, including quantitative differences in predatory behaviour, seemed to be related to differences in the effectiveness of the cryptic morphology of Portia in concealing the spider in its natural habitat (‘effective crypsis’). The results of the study supported, in general, Jackson & Blest’s (1982a) hypothesis of salticid evolution which, in part, proposes that salticid ancestors were web builders with poorly developed vision and that acute vision evolved in conjunction with the ancestral spiders becoming proficient as araneophagic invaders of diverse types of webs.     

Thermotolerance,cell filamentation,and induced protein synthesis in psychrophilic and psychrotrophic bacteria

Both the psychrophile Aquaspirillum arcticum and the psychrotroph Bacillus psychrophilus were found to acquire thermotolerance when either heat shocked or treated with nalidixic acid; two conditions which also resulted in the induction of heat shock proteins and/or stress proteins and also cell filamentation. The possible relatedness of acquisition of thermotolerance and cell filamentation was examined by inhibiting cell filamentation with 1.5% KCl. A. arcticum cells which were heat shocked in the presence of KCl did not become filamentous nor acquire thermotolerance suggesting that these two responses may be related. On the other hand, when cells of B. psychrophilus were treated in a similar fashion, they also were prevented from cell filamentation but their ability to become thermotolerant was unaffected. When A. arcticum cells were heat shocked in the presence of chloramphenicol, heat shock protein synthesis was inhibited but not the acquistion of thermotolerance. Similar experiments with B. psychrophilus revealed that partial induction of heat shock proteins still occurred; however, no thermotolerance was exhibited.Abbreviations hsp(s) heat shock proteins(s) - SEM standard error of the mean     

The coconut mite, Aceria guerreronis, in Benin and Tanzania: occurrence, damage and associated acarine fauna

The coconut mite Aceria guerreronis (Eriophyidae) is considered the most important pest of coconut fruits in Africa; however, quantitative knowledge about its distribution and abundance is lacking. We conducted four diagnostic surveys—three in Southern Benin and one along the coast of Tanzania—to determine the distribution of A. guerreronis and the severity of its damage to coconut fruits, as well as the diversity and abundance of other associated mites and potential natural enemies. Aceria guerreronis was found in all visited plantations with the percentage of damaged fruits varying considerably among plantations—67–85% in Benin and 43–81% in Tanzania. Overall, 30–40% of the fruit surfaces were damaged by A. guerreronis. Damage severity increased with fruit age and negatively affected fruit weight of 7- to 12-months-old fruits. Aceria guerreronis was by far the most abundant mite on coconut fruits but its abundance depended on fruit age. The highest densities of A. guerreronis were observed on 3- to 4-months-old fruits. Neocypholaelaps sp. (Ameroseiidae) was the most abundant mite on inflorescences. Three species of predatory mites (Phytoseiidae)—Neoseiulus baraki, N. neobaraki and N. paspalivorus—were the most commonly found predatory mites beneath the coconut bracts in association with A. guerreronis. Neoseiulus neobaraki was the prevailing predator in Tanzania while N. paspalivorus was the most frequent predator in Benin. Other mites found beneath the bracts were the herbivore Steneotarsonemus furcatus (Tarsonemidae) and the detritivore and fungivore Tyrophagus putrescentiae (Acaridae).     

Physical and functional mapping of Tn2603, a transposon encoding ampicillin, streptomycin, sulfonamide, and mercury resistance

Summary A map of cleavage sites for restriction endonucleases EcoR1, BamHI, HindIII, and SalI on Tn2603, a transposon encoding resistance to ampicillin, streptomycin, sulfonamide, and mercury, was constructed by an analysis of restriction cleavage patterns of plasmid pMK1.:: Tn2603 and its deletion derivative. By cloning the fragments generated from pMK1::Tn2603 with these restriction endonucleases to a pACYC184 plasmid vehicle, the regions necessary for expression of resistance were located on the restriction cleavage map of Tn2603. Ampicillin, streptomycin, and sulfonamide-resistance genes were mapped in a cluster on the region between the center and the right and the mercury-resistance gene was located to the left of the map. The final functional map of Tn2603 was compared with those of Tn4 and Tn21 and the evolutional relationships between them were discussed.     

Levels of iron, zinc, and copper in aqueous humor, lens, and serum in nondiabetic and diabetic patients

The purpose of this study was to investigate iron (Fe), zinc (Zn), and copper (Cu) levels of aqueous humor, lens, and serum in nondiabetics and diabetics and to determine the effects of diabetes on Fe, Zn, and Cu contents in the lens. Fe, Zn, and Cu contents of aqueous humor, lens, and serum samples of 19 patients (9 nondiabetic patients with a mean age of 62.3±5.4 yr, and 10 diabetic patients with a mean age of 59.5±5.9 yr) were analyzed by atomic absorption spectrometry using a prospective study design. The lens levels of Cu in diabetic patients were significantly higher compared with nondiabetic patients (p=0.02); however; there was no difference in the other elements (Zn, Fe; p=0.28, p=0.74, respectively). The levels of Fe, Zn, and Cu in the aqueous humor and serum of diabetic patients were not found to be statistically significant when compared to nondiabetics (p=0.46, p=0.11, p=0.18, and p=0.22, p=0.43, p=0.72, respectively). These results demonstrate that increased Cu content of the lens presumably has a greater association with the development of lens opacification in diabetics than Zn and Fe content.     

Lake acidity,fish predation,and the distribution and abundance of some littoral insects

Densities of Corixidae (Hemiptera), larval Odonata, and large larval Trichoptera were estimated in the littoral zone of small lakes in an acid-stressed area near Sudbury, Ontario. Fish were present in some lakes and absent in others, and fishless lakes occurred across a wide range of pH. Corixidae were significantly more abundant in lakes without fish than in lakes with fish, and their numbers were not related to the pH of fishless lakes. Anisoptera (Odonata) larvae tended to be more numerous in benthic samples from fishless lakes than from lakes with fish, and their exuviae were significantly more abundant around fishless lakes. In most lakes, the assemblage was dominated by three species; Leucorrhinia glacialis, Libellula julia, and Cordulia shurtleffi. In lakes containing white sucker, Catostomus commersoni, Gomphus spp. were most numerous. In the most acid fishless lakes, L. julia was uncommon, and L. glacialis was extremely abundant. In fishless lakes, numbers of Anisoptera larvae and exuviae were negatively correlated with pH, though species richness was positively correlated with pH. Exuviae of Zygoptera (Odonata) were more abundant around fishless lakes, irrespective of pH. Larvae of Limnephilus (Trichoptera) were most abundant in non-acid fishless lakes, and absent at pH<5.2. Abundances of Banksiola (Trichoptera) were negatively correlated with the pH of fishless lakes.     

Childhood Psychological,Physical, and Sexual Maltreatment in Outpatients with Binge Eating Disorder: Frequency and Associations with Gender,Obesity, and Eating‐Related Psychopathology

Objective: To examine rates of reported childhood maltreatment in binge eating disorder (BED), and to explore associations with obesity, gender, eating disorder features, and associated functioning. Research Methods and Procedures: Subjects were 145 consecutive outpatients with BED as defined in the Diagnostic and Statistical Manual of Mental Disorders, 4^th edition. Subjects were interviewed and they completed questionnaires to assess eating disorder features and functioning. The Childhood Trauma Questionnaire was given to assess childhood maltreatment in five domains (emotional abuse, physical abuse, sexual abuse, emotional neglect, and physical neglect). Results: A total of 83% of BED patients reported some form of childhood maltreatment. A total of 59% of BED patients reported emotional abuse, 36% reported physical abuse, 30% reported sexual abuse, 69% reported emotional neglect, and 49% reported physical neglect. There were no differences in the distribution of any form of childhood maltreatment by gender or by obesity status. The different forms of maltreatment were not associated with variability in current body mass index, binge eating, or in the attitudinal features of eating disorders. Only one of the five forms of maltreatment (physical neglect) was associated with dietary restraint in women. Emotional abuse was significantly associated with greater body dissatisfaction, higher depression, and lower self‐esteem in men and women and sexual abuse was associated with greater body dissatisfaction in men. The different forms of maltreatment were unrelated to the age at onset of overweight, dieting, or binge eating. Discussion: BED outpatients reported a wide range of childhood experiences of maltreatment that do not differ by gender or obesity status. Different forms of maltreatment were not associated with the onset of overweight, dieting, or binge eating, or with variability in current body mass index or eating disorder features (except for one association between physical neglect and dietary restraint). Reports of emotional abuse were associated with greater body dissatisfaction and depression and lower self‐esteem in men and women and sexual abuse with greater body dissatisfaction in men.     

Relationships between benthic cover, current strength, herbivory, and a fisheries closure in Glovers Reef Atoll, Belize

Benthic cover, current strengths, and fish abundance and diversity were examined on 150 lagoonal patch reefs and mapped to determine their distribution, inter-relationships, and relationship to the fisheries closure in Glovers Reef Atoll. Current strength was highest at both the northern and southern ends of the atoll and largely controlled by local wind and weakly by tidal forcing. Benthic functional group distributions varied throughout the atoll and had distinct areas of dominance. In contrast, dominance of coral species was weaker, reflecting the lost cover and zonation of Acropora, Porites, and Montastraea that were reported in the 1970s. Hard and soft corals dominated the windward rim, while the central and leeward lagoon had lower current strengths and sea grass and fleshy green algae were relatively more abundant. Brown erect algae were relatively more common in the north and calcifying green and red algae the southern ends of the atoll. Only Montastraea-Agaricia agaricites distributions were similar to reports from the 1970s with high relative dominance in the southern and northeast atoll. The central-northern zone, which was described as an Acropora zone in the 1970s, was not recognizable, and Porites porites, P. astreoides, Millepora alcicornis, and Favia fragum were the most abundant species during this survey. Hard and soft coral cover abundance declined away from the reef rim and tidal channels and was associated with fast seawater turnover and high surgeonfish abundance. Consequently, the windward rim area has retained the most original and persistent hard-soft coral and surgeonfish community and is considered a priority for future management, if the goal is to protect coral from fishing impacts.     

Control of potato cyst-nematode, Globodera rostochiensis, and root-knot nematode, Meloidogyne incognita, by organosphosphorus, carbamate, benzimidazole and other compounds

Control of potato cyst-nematode, Globodera rostochiensis, was examined on potato or tomato in pots and on potato in field plots by various chemicals incorporated into the soil at planting. The most effective nematicides were organophosphorus compounds, generally of the type O,O-diethyl O-phosphoro-thioates or O,O-diethyl phosphorodithioates, carbamates and benzimidazoles. In organic soils, the more lipophilic compounds were less effective, presumably because of sorption onto soil organic matter. Foliar sprays of chemicals, including oxamyl which is known to be translocated to roots, gave poor control of G. rostochiensis. The root-knot nematode, Meloidogyne incognita, on tomato, widely used in screening for nematicidal activity, was controlled by aldicarb or phoxim incorporated into the soil at planting, but not by benomyl or thiabendazole, in contrast to the moderate effectiveness of these latter two chemicals against G. rostochiensis.     

Diet composition and prey selection of the pike,Esox lucius,in Çivril Lake,Turkey

Diet composition and prey selection of pike (Esox lucius) were studied in Çivril Lake, Turkey. The lake is eutrophic in character with a surface area of ca. 64 km^?2 and mean depth of 3 m. Stomach contents of 409 specimens were collected between October 2003 and April 2005. Pike diet included 10 prey fish species, two Crustaceae, four Insecta, one Hirudinae and one Amphibia. Feeding was homogeneous, with most pike specializing in prey fish and a few pike specializing on miscellaneous items. Feeding activity varied by season and ontogeny. Stomach fullness and the percentage of fish with prey were highest in spring and in small pike, while feeding intensity was lowest in winter and in large sized pike. Diet composition was dominated by fish, including Carasius gibelio, Chondrostoma meandrense, Esox lucius, Gambusia affinis, Gobio gobio, Hemigrammocapoeta kemali, Leuciscus cephalus, and Tinca tinca. Crustacea were also a significant component in spring and in small sized pike. The most important prey items were C. meandrense, Gammarus sp., H. kemali, and L. cephalus. Pike feeding in winter and summer was homogeneous, specializing mainly on fish as prey, while the diet in spring and autumn was heterogeneous with some pike specializing on Gammarus sp. Cannibalism at 8.7% was observed only in the large sized pike (>40 cm). Pike strongly preferred C. meandrense (Selectivity index V = 0.372; χ² = 27.739; P < 0.01), G. gobio (V = 0.192; χ² = 7.350; P < 0.01) and T. tinca (V = 0.146; χ² = 4.257; P < 0.05) despite their low abundance in the lake. Hemigrammocapoeta kemali was the most abundant prey fish in the environment; however, it was a negatively selected food item (V = ?0.358; χ² = 25.642; P < 0.01). Cyprinus carpio also inhabits the lake, but was not preferred by pike (V = ?0.056; χ² = 0.625; P > 0.05).     

Structure, distribution of species and inundation in a riparian forest of Rio Paraguai, Pantanal, Brazil

A phytosociological study was conducted in a riparian forest of the Rio Paraguai near Corumbá and Ladário in the state of Mato Grosso do Sul, Brazil. The topographic distribution of species was correlated with durations of the river's seasonal floodings and the cumulative time of flooding between 1974 and 1995. One hundred and eight contiguous 10×10 m plots were systematically established. All individuals with more than 15 cm of girth at breast height (gbh=1.3 m) were sampled. A total of 695 individuals distributed among 37 species, 35 genera and 23 families were found. The Shannon index (H′) for species diversity was 2.7. The highest importance value (IV) was found for Inga vera ssp. affinis, followed by Triplaris gardneriana, Ocotea diospyrifolia, Crataeva tapia and Vochysia divergens. The plots were classified into two groups according to their distance from the margin, applying Ward's method of classification and principal coordinate analysis (PCO) on the same Bray Curtis distance matrix. The topical environments were divided into four bands by Two-Way Indicator Species Analysis (TWINSPAN), and the species were also grouped into four groups. Flooding in these groups ranged from regular inundation in all 23 years of the historical series of the Ladário gauge to sporadic flooding for a maximum of 2 consecutive years.     

Epibiosis and parasitism of coquina clam Donax spp.: Location,location, location!

Cryptic species of coquina clams Donax fossor and D. variabilis carry the hydroid epibiont Lovenella gracilis and are infected with metacercariae of the monorchiid parasites Lasiotocus trachinoti and L. choanura. The associations among this host–epibiont–parasite system were investigated. Fifty clams were collected at low tide over 3 days in June 2020 in South Carolina from each of three groups: clams with no hydroid from the upper intertidal zone and clams with and without hydroids from the swash zone. Clams were measured, identified using a newly developed PCR-RFLP, and examined for infection by metacercariae. Parasites were identified based on cercarial morphology and on metacercariae habitat in the clams. D. fossor was most often found in the swash zone and D. variabilis in the upper intertidal zone. The hydroid was most often associated with D. fossor, which was more infected by both digeneans than D. variabilis. Mean abundance of metacercariae of L. choanura was higher than that of L. trachinoti in both clams and increased over time for both parasites, because higher infection was correlated with larger clams. Greater time spent in the water by individuals of D. fossor appears to best explain these results, with the presence of the hydroids also being associated with higher infection by metacercariae in this coquina. Integration of D. variabilis in both digenean life cycles appears to lead to a positive outcome for the parasites as prevalence and abundance of infection were high; however, because D. variabilis is most frequent in the upper intertidal, more emersed, zone, it is likely deleterious to the epibiont to establish on this clam.     

Age and growth of ocellated icefish, Chionodraco rastrospinosus DeWitt and Hureau, 1979, from the South Shetland Islands

Age and growth of ocellated icefish, Chionodraco rastrospinosus, were investigated using counts of annual growth increments from sagittal otoliths. Samples were collected during research surveys by benthic trawl carried out around Elephant and South Shetland Islands in January–February 2002 and December 2006–January 2007. A total of 290 specimens were selected for the study, consisting of 120 females and 170 males. The age of fish was estimated by counting annuli on transverse sections obtained by grinding and polishing whole otoliths embedded in epoxy resin. The precision-of-age estimates within and between readers were tested applying both the average percent error (APE) and the coefficient of variation (CV). The estimated age-range was 1–12 for both sexes of C. rastrospinosus. Applying the von Bertalanffy growth function to the age–length data, a growth curve was obtained for each sex. The estimated values of VB growth parameters L _∞ and k were, respectively, 47.9 cm and 0.28 for females and 42.9 cm and 0.36 for males. Compared to other congeneric species, the growth performance of C. rastrospinosus was relatively high, being 2.82 and 2.81 in males and females, respectively. Age at sexual maturity was estimated to be about 4 years in both sexes. C. rastrospinosus captured in the studied area consisted mainly of adult specimens between 3 and 8 years, with few older fish.     

Litterfall Mass,Chemistry, and Nutrient Retranslocation in a Monodominant Forest on Maracá Island,Roraima, Brazil1

Maracá Island is on the boundary of the Amazon rain forest and the Rio Branco-Rupunini savanna. The annual rainfall is ca. 1800 mm, with a dry season from October-March and a wet season from April-September. A forest type dominated by Peltogyne gracilipes (Caesalpiniaceae) occurs on parts of the island and the adjacent mainland, the least species-rich (for trees > 10 cm DBH) of any recorded in Brazilian Amazonia. The goal of this study was to test the hypothesis that the dominance by Peltogyne is associated with an unusual litterfall mass, nutrient concentrations, or retranslocation. Three plots (50 × 50 m) were set up in each of three forest types: (1) Peltogyne-rich forest (PRFa), dominated by Peltogyne gracilipes; (2) Peltogyne-poor forest (PPF), with a sparse occurrence of Peltogyne; and (3) forest without Peltogyne (FWPa). Litterfall was collected for 360 d at ca 15-d intervals in 11 randomly positioned traps (0.32 m²) per plot. Mature Peltogyne leaves were collected at random from three randomly selected understory Peltogyne trees in each of the three PRFa plots during the early dry and early wet season. Additionally, young Peltogyne leaves were collected during the early wet season. Chemical analyses were made on bulked (on a 2-mo basis) litterfall samples and young and mature Peltogyne leaves. The estimated annual litterfall was similar among PRFa (7.9 t/ha), PPF (9.1 t/ha) and FWPa (8.6 t/ha); however, PRFa was distinguished by its litterfall seasonality, because of the deciduous Peltogyne, and its higher concentrations of Ca (9.3 compared to 6.5 mg/g in FWPa) and Mg (3.2 compared to 1.9mg/g in FWPa). About 40–50 percent of N and P, 25–41 percenr of K, and 2–13 percent of Mg were rerranslocated from Peltogyne leaves.     

Associations of Cyanobacterial Toxin,Nodularin, with Environmental Factors and Zooplankton in the Baltic Sea

Concentrations of a cyanobacterial toxin, nodularin, were measured in the Baltic Sea in 1998 and 1999. Statistical associations of nodularin concentrations with environmental factors were tested by multiple regression analysis. To reveal the toxin-producing organism, colonies of Aphanizomenon and filaments of Nodularia were picked and analyzed for peptide toxins. It was also investigated whether there was an association with zooplankton and Nodularia. All the measured seston samples contained nodularin, but other toxins were not detected by the HPLC analysis. In both years, the highest nodularin concentrations were found at the surface water layer. The nodularin concentrations were positively correlated with silicate concentrations in water. High concentrations of silica in surface water may indicate recent upwelling, which in turn renders surface water rich in nutrients. This upwelling is likely to intensify cyanobacterial growth and toxin production, which may explain this rather unexpected result. The picked Aphanizomenon colonies did not contain nodularin and the dissolved nodularin concentrations were below detection limit. Thus it was concluded that most of the nodularin was bound to Nodularia cells. The abundances of zooplankton (copepods, rotifers, and cladocerans) were unrelated to Nodularia, but were positively associated with Aphanizomenon.