Ontogenetic diet shift in Commerson’s dolphin (Cephalorhynchus commersonii commersonii) off Tierra del Fuego

The Commerson’s dolphin (Cephalorhynchus c. commersonii, Lacépède, 1804) is the most common endemic dolphin of the coastal waters of Tierra del Fuego incidentally caught in artisanal coastal gill nets. A better understanding of its trophic ecology is essential to facilitate the effective management and conservation of its population. The aim of this study was to analyze possible shifts in diet among age and sex classes by analyzing bone collagen δ¹³C and δ¹⁵N values collected from 220 individuals along the coast of Tierra del Fuego. Additional analysis of potential prey allowed us to use a stable isotope mixing model to quantify resource use. Isotopic comparisons suggest that all age classes share the same foraging areas. We found, however, a significant dietary shift: juveniles consume a higher mean (±SD) proportion (60 ± 7 %) of pelagic Sprattus fuegensis than adults (36 ± 10 %), and the consumption of benthopelagic species such as Illex argentinus and Loligo gahi is higher in adults (33 ± 12 %) than juveniles (20 ± 7 %). This may result from an improvement in foraging skills and expansion of habitats in adulthood. While males move greater distances in search of mates and resources, a lack of isotopic differences between the sexes suggests little evidence for sex-related resource partitioning. A significant decrease in δ¹⁵N values between calves and juveniles indicates a weaning period between 0.5 and 1 year as was shown in previous captive studies on this species. Our results also suggest that artisanal fisheries, despite being a major source of mortality, do not affect the long-term food habits of Commerson’s dolphin since they showed a weak trophic overlap.     

Mother–calf interactions and social behavior development in Commerson’s dolphins (Cephalorhynchus commersonii)

Mother–calf interactions and the behaviors of mothers during separation from their calves were examined in four Commerson’s dolphin (Cephalorhynchus commersonii) mother–calf pairs. Four infants were observed: 56.8 h over 30 days from birth to 263 days of age, 36.9 h over 20 days from birth to 149 days of age, 10.4 h over 3 days from birth to 2 days of age, and 15.0 h over 3 days from birth to 2 days of age. All four pairs shared common characteristics in the rate and frequencies of mother–calf interactions and the behaviors of mothers during the first week of life. After the first week, individual differences in changes in the frequency of each behavior were observed. The three behaviors considered representative of maternal care (parallel swimming, synchronous breathing, and body-to-body contact) were frequently performed in the first week; thereafter, the frequencies declined. Separate behaviors of mothers were infrequent during the first week and increased with an increase in infants’ age. Bumping by infants increased with time, suggesting an increase in soliciting by calves and conflict between mothers and calves. The frequency of flipper-to-body rubbing also changed but in a complex manner, probably because the calves needed to learn how to perform this behavior from their mothers and because initiator and recipient of this behavior can be changed quickly.     

Feeding aggregation and aggressive interaction between bottlenose (Tursiops truncatus) and Commerson’s dolphins (Cephalorhynchus commersonii) in Patagonia,Argentina

We report the first recorded interactions between bottlenose dolphin (Tursiops truncatus) and Commerson’s dolphins (Cephalorhynchus commersonii). The diurnal behavioral patterns of bottlenose dolphins in Bahía Engaño, Argentina, were similar to those described for other coastal populations around the world. The majority of the feeding bouts were recorded near the mouth the Chubut River. When not feeding near the river, bottlenose dolphins generally swam along the coast, and interactions with Commerson’s dolphins were recorded very close to the shore on two occasions during a 3-year period. In the first event, both species were feeding on a fish school. The second interaction was aggressive in nature, involving one juvenile and three adult bottlenose dolphins with several Commerson’s dolphins. Two of the adult bottlenose dolphins attacked the Commerson’s dolphins. We propose that the observed behavior represented defense of the juvenile bottlenose dolphin.

     

Selenium–Mercury Interactions in Man and Animals

Selenium–mercury interactions were most extensively studied in relation to alleviation of Hg toxicity by added selenium. This presentation considers the influence of mercury on endogenous selenium, on its tissue and cellular “status” after lifelong or acute exposure to mercury vapor (Hg^o). Discussed are data obtained from (1) humans living near or working in a mercury mine, and (2) rats experimentally exposed in the mine. Mercury vapor is unique—or similar to methylmercury—because of its ability to penetrate cell membranes and so invade all cells, where it is oxidized in the biologically active form (Hg⁺⁺) by catalase. Such in situ-generated ions can react with endogenously generated highly reactive Se metabolites, like HSe−, and render a part of the selenium unavailable for selenoprotein synthesis. Data on human populations indicate that in moderate Hg exposure combined with an adequate selenium supply through diet, Se bioavailability can be preserved. On the other hand, the results of an acute exposure study emphasize the dual role of selenium in mercury detoxification. Besides the well-known Se coaccumulation through formation of nontoxic Hg–Se complexes, we observed noticeable Se (co)excretion, at least at the beginning of exposure. The higher Hg accumulation rate in the group of animals with lower basal selenium levels can also point to selenium involvement in mercury excretion. In such conditions there is a higher probability for decreased selenoprotein levels (synthesis) in some tissues or organs, depending on the synthesis hierarchy.     

Selenium concentration and glutathione peroxidase activity in cow’s milk

Samples of raw or pasteurized cow’s milk and infant formula were assayed for glutathione peroxidase (GSH-Px) activity, selenium (Se), and total protein. GSH-Px activity was detected in raw milk, but not in market-pasteurized milk or infant formula. The correlation between GSH-Px activity and Se levels was significant, even when the influence of protein level was removed. This result implies a role of GSH-Px as one of biologically active forms of Se in raw milk. Absence of GSH-Px activity in pasteurized milk and infant formula result from the heating process in these productions, because the heating of raw milk gave an irreversible inactivation of GSH-Px. Both GSH-Px activity and Se levels had significant correlation with protein level, but not so when the respective influences of Se and GSH-Px levels were removed. In raw cow’s milk, Se content was 23 ng/mL and GSH-Px activity was 20 U/mL. About 12% of Se was bound to GSH-Px, and 0.003% of protein was GSH-Px. Raw milk obtained in July contained higher levels of Se, GSH-Px, and protein than that in November. Data for cow’s milk were discussed in relation to those for human milk and those in New Zealand.     

Mitochondrial DNA variation and population structure of Commerson’s dolphins (<Emphasis Type="Italic">Cephalorhynchus commersonii</Emphasis>) in their southernmost distribution

The Commerson’s dolphin, Cephalorhynchus commersonii, is found in shallow waters of the continental shelf off the eastern coast of South America between 40°S and 56°S. This species is taken incidentally in artisanal gillnet fisheries, especially along the shallow coastline of northern Tierra del Fuego and southern Patagonia. The biological importance of by-catch is likely to be underestimated if the boundaries of subpopulations are not properly defined. Here, we report on the sequence variation of the mitochondrial DNA control region of the Commerson’s dolphin from five areas defined in Tierra del Fuego, Argentina and Chile, to provide a preliminary assessment of population structure where conservation efforts are most needed. A 466 bp fragment of the mitochondrial DNA control region was sequenced from 196 samples of skin, teeth and bone, defining 20 haplotypes from 17 polymorphic sites. Nucleotide (π = 0.40%) and haplotype (h = 0.807) diversity were low compared to some other odontocete populations, but similar to that of other species of this genus. Genetic differentiation evaluated through analyses of molecular variance (AMOVA) showed significant overall differences among areas within Tierra del Fuego (Φ _ST  = 0.059, P < 0.01). An analysis of sex-specific population structure suggested that the dispersal rates of both females and males are low, indicative of females displaying greater site fidelity. The results from mtDNA control region sequences alone revealed significant differentiation among studied areas, which should be considered as independent management units. We recommend that the impact of localized gillnet mortalities should be managed on a local scale in these areas of Tierra del Fuego.     

Determination of Mercury and Methylmercury in Hair of the Czech Children’s Population

The developed method for mercury speciation analysis has been validated and used for the biomonitoring study of mercury species in human hair. Statistical evaluation proved the reliability of simplified determination of inorganic mercury (difference between total mercury and methylmercury). The results of the validation showed that the method is very well suitable for the determination of both species of mercury in hair for biomonitoring purposes. Non-exposed schoolchildren from three areas in the western and central part of the Czech Republic were chosen as the target group. Tenth of a microgram per gram of the total mercury were generally found in the analyzed hair; values higher than 1 μg g⁻¹ were detected only exceptionally. Comparable results were obtained for two western areas and differed significantly from those for the third area located in the central part of the Czech Republic. In the areas examined, the mean methylmercury contents amounted to 23–46% of the total mercury in the hair. The results confirm an assumption that exposure to mercury does not pose a significant risk to the population in the Czech Republic.     

Selenium and its relationship with selenoprotein P and glutathione peroxidase in children and adolescents with Hashimoto’s thyroiditis and hypothyroidism

The essential trace element selenium (Se) is required for thyroid hormone synthesis and metabolism. Selenoproteins contain selenocysteine and are responsible for biological functions of selenium. Glutathione peroxidase (GPx) is one of the major selenoproteins which protects the thyroid cells from oxidative damage. Selenoprotein P (SePP) is considered as the plasma selenium transporter to tissues. The aim of this study was to evaluate serum Se and SePP levels, and GPx activity in erythrocytes of children and adolescents with treated Hashimoto’s thyroiditis, hypothyroidism, and normal subjects.Blood samples were collected from 32 patients with Hashimoto’s thyroiditis, 20 with hypothyroidism, and 25 matched normal subjects. All the patients were under treatment with levothyroxine and at the time of analysis all of the thyroid function tests were normal. GPx enzyme activity was measured by spectrophotometry at 340 nm. Serum selenium levels were measured by high-resolution continuum source graphite furnace atomic absorption. SePP, TPOAb (anti-thyroid peroxidase antibody), and TgAb (anti-thyroglobulin antibody) were determined by ELISA kits. T₄, T₃, T₃ uptake and TSH were also measured.Neither GPx activity nor SePP levels were significantly different in patients with Hashimoto’s thyroiditis or hypothyroidism compared to normal subjects. Although GPx and SePP were both lower in patients with hypothyroidism compared to those with Hashimoto’s thyroiditis and normal subjects but the difference was not significant. Serum Se levels also did not differ significantly in patients and normal subjects. We did not find any correlation between GPx or SePP with TPOAb or TgAb but SePP was significantly correlated with Se.Results show that in patients with Hashimoto’s thyroiditis or hypothyroidism who have been under treatment with levothyroxine and have normal thyroid function tests, the GPx, SePP and Se levels are not significantly different.     

Maltotriose transport and utilization in Baker’s and Brewer’s yeast

Maltotriose is metabolized by baker’s and brewer’s yeast only oxidatively, with a respiratory quotient of 1.0, the being, depending on the strain used, 0–11, as compared with of 6–42μL CO₂ per h per mg dry substance. The transport appeared to proceed by facilitated diffusion (no effects of NaF, iodoacetamide and 3-chlorophenylhydrazonomalononitrile) with a K_T of more than 50mm and was inhibited by maltose > maltotriose > methyl-α-D-glucoside > maltotetraose >D-fruetose >D-glucose. The transport was present constitutively in bothSaccharomyces cerevisiae (baker’s yeast) and inS. uvarum (brewer’s yeast) and it was not significantly stimulated by preincubation with glucose or maltose. The pH optimum was 4.5–5.5, the temperature dependence yielded an activation energy of 26 kJ/mol.     

Chasing genes in Alzheimer’s and Parkinson’s disease

Alzheimers disease (AD), the most common type of dementia, and Parkinsons disease (PD), the most common movement disorder, are both neurodegenerative adult-onset diseases characterized by the progressive loss of specific neuronal populations and the accumulation of intraneuronal inclusions. The search for genetic and environmental factors that determine the fate of neurons during the ageing process has been a widespread approach in the battle against neurodegenerative disorders. Genetic studies of AD and PD initially focused on the search for genes involved in the aetiological mechanisms of monogenic forms of these diseases. They later expanded to study hundreds of patients, affected relative-pairs and population-based studies, sometimes performed on special isolated populations. A growing number of genes (and pathogenic mutations) is being identified that cause or increase susceptibility to AD and PD. This review discusses the way in which strategies of gene hunting have evolved during the last few years and the significance of finding genes such as the presenilins, -synuclein, parkin and DJ-1. In addition, we discuss possible links between these two neurodegenerative disorders. The clinical, pathological and genetic presentation of AD and PD suggests the involvement of a few overlapping interrelated pathways. Their imbricate features point to a spectrum of neurodegeneration (tauopathies, synucleinopathies, amyloidopathies) that need further intense investigation to find the missing links.     

Assessing Plasma Levels of Selenium,Copper, Iron and Zinc in Patients of Parkinson’s Disease

Trace elements have been recognized to play an important role in the development of Parkinson’s disease (PD). However, it is difficult to precisely identify the relationship between these elements and the progression of PD because of an insufficient number of patients. In this study, quantifications of selenium (Se), copper (Cu), iron (Fe) and zinc (Zn) by atomic absorption spectrophotometry were performed in plasma from 238 PD patients and 302 controls recruited from eastern China, which is so far the largest cohort of PD patients and controls for measuring plasma levels of these elements. We found that plasma Se and Fe concentrations were significantly increased whereas Cu and Zn concentrations decreased in PD patients as compared with controls. Meanwhile, these four elements displayed differential changes with regard to age. Linear and logistic regression analyses revealed that both Fe and Zn were negatively correlated with age in PD patients. Association analysis suggests that lower plasma Se and Fe levels may reduce the risk for PD, whereas lower plasma Zn is probably a PD risk factor. Finally, a model was generated to predict PD patients based on the plasma concentrations of these four trace elements as well as other features such as sex and age, which achieved an accuracy of 80.97±1.34% using 10-fold cross-validation. In summary, our data provide new insights into the roles of Se, Cu, Fe and Zn in PD progression.     

Selenium in sediment and food webs of the Tapajós River basin (Brazilian Amazon) and its relation to mercury

BackgroundWe investigated Se levels along the Tapajós River basin - which is an important tributary of the Amazon River - and the possible antagonistic effect of Se in Hg availability. This is the first study to investigate Se transfer from abiotic to biotic compartments and along the food chain in aquatic ecosystems of the Amazon basin.MethodsSe concentrations were measured in superficial sediment (n = 29), plankton (n = 28) and fishes (n = 121) along two stretches of the Tapajós River basin (Tap_up/mi and Tap_low), comprising approximately 500 km with different hydrological characteristics.ResultsSe concentrations in sediment were significantly higher in the Tap_low (345−664 μg kg⁻¹) than in the Tap_up/mi (60−424 μg kg⁻¹). The seasonal flooding of the Amazon River probably helps to carry selenium-rich sediment to the Tapajós mouth (Tap_low stretch). We suggest that Se in sediment could decrease the bioavailability of Hg resulting in lower MeHg concentrations in fish, as observed in the Tap_low (45−934 μg kg⁻¹). Sediment and plankton were positively correlated in relation to their Se concentrations (r = 0.62; p = 0.001) suggesting that sediment can possibly be the main source of Se to plankton. Our data indicate Se uptake by primary consumers, as noted in phytoplankton levels. The decrease of Se concentrations along the food chain was also noteworthy.ConclusionThis work elucidates some aspects of Se biogeochemistry in the Amazon basin and shows its importance regarding Hg cycles in aquatic ecosystems.     

Selenium speciation analysis in the cerebrospinal fluid of patients with Parkinson’s disease

BackgroundThe aim of the study was to investigate if speciation analysis by liquid chromatography coupled to mass spectrometry could be used to detect organic and inorganic binding forms of selenium in the cerebrospinal fluid (CSF) of patients with Parkinson’s disease (PD) and age-matched control subjects (AMC).MethodsPD patients and control subjects were enrolled from three different neurological departments. CSF samples were collected according to standardized biomarker protocols and subjected to inductively coupled plasma mass spectrometry (ICP-MS) for total selenium determination and ion exchange chromatography (IEC) hyphenated to ICP-MS for selenium speciation analysis.Results75 PD patients and 68 age-matched controls were enrolled for speciation analysis. 8 different species could be detected, but only selenoprotein P (SELENOP), human serum albumin-bound Se (Se-HSA), selenomethionine (Se-Met) and an unidentified Se-compound (U2) presented with more than 50% values above the limit of quantification, without showing significant differences between both groups (p > 0.05). The Se-HSA / Se-Met ratio yielded a significant difference between PD and AMC (p = 0.045). The inorganic species Se-IV and Se-VI were only detectable in a minor part of PD and AMC samples. A highly significant correlation between total selenium levels and SELENOP (PD p < 0.0001; AMC p < 0.0001) and Se-HSA (PD p < 0.0001; AMC p < 0.0001) could be demonstrated, respectively.ConclusionsSpeciation analysis yielded new insight into selenium homeostasis in PD but cannot be used to establish a diagnostic biomarker. The small number of detectable values for Se-IV and Se-VI suggests an inferior role of these potentially neurotoxic binding forms in PD pathology in contrast to other neurodegenerative disorders.     

Mercury–Selenium Species Ratio in Representative Fish Samples and Their Bioaccessibility by an In Vitro Digestion Method

The potential toxicity of mercury (Hg) content in fish has been widely evaluated by the scientific community, with Methylmercury (MeHg) being the only legislated species (1 mg kg⁻¹, maximum concentration allowed in predatory fish). On the other hand, selenium (Se) is recognized to decrease its toxicity when both elements are simultaneously administrated. In the present paper, the total content of Se and Hg and their species in fish of high consumption, such as tuna, swordfish, and sardine, have been evaluated. The percentage of MeHg is higher than 90% of total Hg content. The results show that, for all of them, the Se/Hg ratio is significantly higher than one, being the maximum ratio for sardine. As only studying the bioaccessible fraction the extent of a toxic effect caused by an element can be predicted, the bioaccessibility of both analytes through an in vitro digestion method has been carried out. The results show that MeHg in all fishes is very low bioaccessible in both gastric and intestinal digestion. Because the MeHg bioaccessible fraction might be correlated to the Se content, the potential toxicity cannot be only related to the total Hg content but also to Se/Hg ratio.     

Evaluation of Selenium,Redox Status and Their Association with Plasma Amyloid/Tau in Alzheimer’s Disease

The aim of the study was to evaluate blood selenium and antioxidants as possible oxidative stress markers in Alzheimer’s disease (AD) along with amyloid β42 (Aβ42) and tau by comparing them with vascular dementia (VD) and age-matched healthy controls. Selenium, total tau, Aβ42, glutathione (GSH) and malondialdehyde (MDA) levels and the activities of antioxidant enzymes were analysed in the blood of AD patients (n?=?30), VD patients (n?=?35) and controls (n?=?40) from South India. Plasma Aβ42 level was significantly higher (P?<?0.001) in both AD and VD compared to controls. Total tau and tau-to-amyloid ratio were significantly lower in both AD and VD (P?<?0.001), compared to controls, and a significant difference (P?<?0.01 and P?<?0.05, respectively) was also observed between AD and VD. The receiver operating characteristic (ROC) curve-derived cutoff values of <3.5 for tau-to-Aβ42 ratio and <520 pg/ml for total tau showed sensitivity and specificity of around 67–72 % for differentiating AD from VD and around 90 % for AD from controls, indicating that they could serve as reliable AD-specific markers. The MDA levels were significantly higher (P?<?0.001) in both dementia groups along with a significant decrease (P?<?0.001) in reduced GSH levels, indicating elevated oxidative stress and altered redox status in both forms of dementia. Selenium levels did not vary significantly between the three groups. The activity of glutathione peroxidase increased in both AD and VD compared to controls, with a concomitant decrease in glutathione reductase and glucose-6-phospate dehydrogenase (P?<?0.001) activity. The activity of thioredoxin reductase was significantly lower in both patient groups (P?<?0.001) compared to healthy controls. No correlation was observed between selenium and activities of selenoenzymes, tau, Aβ42 or tau-to-Aβ42 ratio, when analysing independently, indicating that blood selenium may not be directly involved in Aβ production and in regulating tau/Aβ42-mediated mechanism in AD. The present study emphasizes the enhanced oxidative stress in AD pathology and plasma tau and tau-to-amyloid ratio as possible markers to differentiate AD from VD. The study also points that blood selenium may not be involved in regulating oxidative stress in AD, and a longitudinal study correlating plasma and cerebrospinal fluid (CSF) selenium and selenoprotein levels is warranted.     

Pater Dr.h.c. Josef Donner (28.2.1909–8.1.1989) in memoriam

Pater Dr.h.c. Josef Donner (28.2.1909–8.1.1989) in memoriam     

Catecholamine metabolism in children with Asperger’s and Kanner’s syndromes

In a stable state children with Asperger’s and Kanner’s syndromes demonstrate a similar decrease in plasma norepinephrine. In the aggravated state, these changes become more expressed and are characterized by a decrease in plasma tyrosine, norepinephrine, normetanephrine, and by an increase in dopamine and homovanillic acid and a decrease in excretion of norepinephrine and an increase in excretion of homovanillic acid, epinephrine and 3-methoxy-4-hydroxyphenylglycol (MHPG). In the aggravated state children with Kanner’s syndrome were characterized by increased plasma MHPG, decreased excretion of tyrosine and increased expression of normetanephrine. The observed imbalance in dopamine and epinephrine/norepinephrine systems suggests importance of combined analysis of changes in catecholamines and their metabolites as the most informative approach in the study of the effect of autistic disorders.     

What Explains Differences in Men’s and Women’s Production?

Researchers commonly use long-term average production inequalities to characterize cross-cultural patterns in foraging divisions of labor, but little is known about how the strategies of individuals shape such inequalities. Here, we explore the factors that lead to daily variation in how much men produce relative to women among Martu, contemporary foragers of the Western Desert of Australia. We analyze variation in foraging decisions on temporary foraging camps and find that the percentage of total camp production provided by each gender varies primarily as a function of men’s average bout successes with large, mobile prey. When men target large prey, either their success leads to a large proportional contribution to the daily harvest, or their failure results in no contribution. When both men and women target small reliable prey, production inequalities by gender are minimized. These results suggest that production inequalities among Martu emerge from stochastic variation in men’s foraging success on large prey measured against the backdrop of women’s consistent production of small, low-variance resources.

Mercury contamination in Lake Xolotlán (Managua)

Total mercury was measured in different compartments of Lake Xolotlán's (Managua) ecosystemviz., sediments, water, fish and men. Sediments from 18 localities at 5 depths inside the sediment (5, 10, 15, 20 and 25 cm) contained an average concentration of 0.62 g Hg.g^–1±0.46 at the surface, with extreme values of 0.16 and 1.8 g.g^–1. The highest concentration was observed at 25 cm depth in front of the chlor-alkaly factory (ELPESA). This maximum is associated with the period of highest production of this factory. The highest mercury concentrations in water were also measured close to the discharge of ELPESA,viz. 787 g.Hg^–1 in January and 506 g.g^–1 in April. The mean mercury concentrations measured in the muscles of the most consumed fish were 0.63 g.g^–1±0.22 (extreme values 0.22 and 1.45) inCichlasoma managuense, and 0.07 g.g^–1±0.14 (extreme values 0.004 and 0.63) inC. citrinellum. The concentration in the liver was 0.79 g.g^–1±1.29 inC. managuense and 0.62 g.g^–1±0.44 inC. citrinellum. Human hairs (n=98) of fishermen and their families contained 5.03 g.g^–1±6.2 (extreme values 0.02 and 38.22). The mean concentration measured in men was 6.22 g.g^–1±6.34 (n=58), and in women 3.39 g.g^–1±5.7 (n=40). The average mercury concentration of hairs of workers of ELPESA was 91.24 g.g^–1±156.9 (extreme values 0.46 and 724.53; n=32). We conclude that total mercury levels in the various ecosystem compartments are very high and mercury contamination in the lake may be considered as dangerous for human health.