Concentrations of dioxins and related compounds in the blood of Fukuoka residents

Blood samples of 152 residents (male 75 and female 77) aged 20-60 years in Fukuoka, Japan, were analyzed for dioxin toxic compounds of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), non-ortho polychlorinated biphenyls (non-ortho PCBs) and mono-ortho polychlorinated biphenyls (mono-ortho PCBs) as well as 35 PCB congeners and 12 chlorinated pesticides by high-resolution gas chromatography/high-resolution mass spectrometry. Average concentrations of dioxin toxic equivalents (TEQ) from PCDDs, PCDFs, non-ortho PCBs, mono-ortho PCBs and their total in the blood of 152 residents were 10.28, 5.56, 7.75, 4.57 and 28.15 ppt in lipid, respectively. These total TEQ levels were comparable to the blood TEQ levels of normal Japanese (n=735). Lipid basis total TEQ levels progressively increased in the males from 17.1 ppt at age 20s to 47.5 ppt at age 50s and in the females from 19.5 ppt at age 20s to 54.5 ppt at age 50s. Dioxin toxic contribution of PCBs to total TEQ was increased from 31% at age 20s to 55% at age 50s. Average concentrations of total 35 PCBs and total 12 pesticides in the blood of 151 residents were 386 and 1079 ppb in lipid, respectively. Average concentrations (ppb in lipid) of total PCBs and total pesticides also progressively increased in the males from 213 and 444 at age 20s to 868 and 2140 at age 50s, respectively, and in the females from 199 and 588 at age 20s to 550 and 1977 at age 50s, respectively. The levels of TEQ, PCBs, hexachlorobenzene, beta-hexachlorocyclohexane, dieldrin, p,p'-dichlorodiphenyldichloroethylene, p,p'-dichlorodiphenyltrichloroethane, trans-nonachlor and cis-nonachlor were positively correlated with each other in most of the combinations, and the highest correlations (r>0.8) were observed between total TEQ and PCBs in both sexes.     

Black Grouse leks on ice: Female mate sampling by incitation of male competition?

Male-male competition is assumed to limit female choice of mates, but it may also help females to choose the most vigorous males. We studied the mate sampling behaviour of female black grouse (Tetrao tetrix) at spatially unstable leks on ice-covered lakes. In the absence of territories and site-dependence in outcomes of fights, the male dominance hierarchy is very evident on ice. When being courted by dominant males, females frequently tried to approach other males. This was frequently prevented because (1) the courting male and the approached male were involved in physical fight, or (2) the dominant male followed the female and the approached male escaped and avoided contact with him. These behaviours express dominance relationships, and the female behaviour could be considered as incitive. Rank in dominance hierarchy was a significant predictor of male mating success. In this case competition between males and female choice worked in parallel favouring male traits correlated with dominance.     

Mass and production rate of ejaculates in relation to monandry/polyandry in butterflies

Summary The mating system maintained in a species has a strong effect on the degree of sperm competition, and certainty of paternity should accordingly influence the optimal sperm content, nutrient content, and mass of the ejaculate. We investigated how ejaculate mass relates to the degree of polyandry in 20 species of butterflies belonging to the families Pieridae and Satyridae. We found that the degree of polyandry has a substantial effect on the reproductive performance of males. The allometric line between ejaculate mass and male body mass has a higher elevation in the pierids compared to the satyrids. The mean number of matings performed by the pierid species is also higher compared to the mean of the satyrids. Thus, the relative ejaculate mass is larger in the family in which polyandry is more pronounced. A within family effect of degree of polyandry on relative ejaculate mass was also detected in the pierids. Since males of polyandrous species on average mate more often than males of monandrous species, they should be expected to have a higher capacity for producing many ejaculates. We investigated how this capacity was influenced by the degree of polyandry, by allowing males of seven different species (Danaus plexippus, Lasiommata megera, Papilio machaon, Pararge aegeria, Pieris napi, Pieris rapae, and Polygonia c-album) to mate twice, with different time intervals between matings. The results showed that not only is the mass of the ejaculate greater in more polyandrous species, but also the rate at which males are able to produce sperm and accessory substances is greater. Hence our data indicate that sperm competition is important for explaining variation in ejaculate mass in butterflies.     

Lysozyme and chitinase in blood and lymphomyeloid tissues of marine fish

The enzyme lysozyme (muramidase) has a degrading effect on chitin, but chitinase is more effective in this respect. Both enzymes occur in fish, but their distribution and function are poorly known. Activities of lysozyme and chitinase were measured in body fluids and tissues of marine fish. Lysozyme was estimated by a plate method, chitinase by a viscosimetric method with glycol chitin as substrate. pH optima and other characteristics were studied. Lysozyme was found in lymphomyeloid (haematopoietic) tissues of chondrichtyan fish (rays, shark, Chimaera monstrosa) and in the plasma and lymph of certain teleosts. Chitinase occurred in lymphomyeloid tissues (except thymus) of chondrichthyans and teleosts, and in the plasma and lymph of teleosts. The results indicate that these enzymes are normal components of fish blood. Probably they are produced by the granulocytes, white blood corpuscles rich in lysosomes. The enzymes might have defence functions in fish blood. Lysozyme is bacteriolytically active while chitinase possibly offers protection against chitincontaining parasites. Very high chitinase activity was found in the pancreas of C. monstrosa. The pancreatic enzyme probably has a digestive function.     

Photosynthetic oxygen production and PAM fluorescence in the brown algaPadina pavonica measured in the field under solar radiation

The effects of solar radiation on photosynthetic oxygen production, pulse amplitude-modulated (PAM) fluorescence and pigmentation were measured in the Mediterranean brown macroalgaPadina pavonica (Linnaeus) Lamouroux under field conditions and natural sunlight. Exposure of thalli to solar radiation for 1 h caused a dramatic decrease of their photosynthetic quantum yield, which recovered to initial levels after they had been placed in the shade for 3 h. Photoinhibition also occurred at the natural growth site ofP. pavonica during the hours of maximal solar irradiance. Photosynthetic oxygen production was also affected by high levels of solar radiation both in algae harvested from the surface and from 6 m depth; oxygen production started to decrease after a few minutes of exposure, and negative values were found after 1 h of solar exposure. Chlorophylla content inP. pavonica also decreased during the hours of maximal solar irradiation. These results suggest that photoinhibition ofP. pavonica occurs during part of a typical summer day on Mediterranean coasts.     

A test of male mating and hunting success in the kestrel: the advantages of smallness?

We tested female choice for male wing and tarsus length and body mass in the kestrel (Falco tinnunculus), a species in which males average about 10% smaller than females. We also studied how male characters are related to their hunting success. In the laboratory, females preferred lighter males with shorter tarsi as mates, if the difference in those characters between competing males was larger than average. Lighter and shorter-winged males seemed to be better hunters than heavier and longer-winged males. Field observations in a year in which voles were scarce suggested that shorter-winged males were also better food providers in courtship feeding than longer-winged males,although in good vole years such a relationship was not found. We argue that females may prefer to pair with smaller males, because they have higher flight performance and better hunting success than heavier males. By doing so, females may gain direct breeding advantages. We conclude that both female choosiness and the hunting efficiency of males well contribute to reversed sexual size dimorphism (RSD, females larger than males) in the kestrel. Received: 18 July 1995/Accepted after revision: 17 August 1996     

Extra-pair paternity and male characteristics in the pied flycatcher

The pied flycatcher (Ficedula hypoleuca) is sexually dichromatic with extreme variation in male plumage coloration. The benefit for males of having black plumage is controversial, and few studies have found evidence for a sexual selection benefit of being black rather than brown. However, blacker males may be better able to achieve extra-pair fertilizations (EPFs), which may be an important component of sexual selection. We studied the role of EPFs in sexual selection in the pied flycatcher by establishing a set-up where two males with different back coloration (blacker vs browner) bred simultaneously near each other. DNA fingerprinting analysis revealed that 11% of offspring resulted from EPFs, and that 22% of broods included extra-pair young (EPY) among 36 nests containing 223 nestlings. We found no evidence that browner males suffered more often from EPFs than blacker males. There was no correlation of male or female morphology or age with EPF frequency. However, breeding pairs with low genetic similarity had EPY in their nests significantly more often. Thus we argue that females paired with genetically dissimilar males may try to avoid the effects of extreme outbreeding by seeking extra-pair copulations (EPCs). Alternatively, incompatibility between genetically dissimilar mates may simply expose females to more extra-pair copulations.     

Resilience and vulnerability of northern regions to social and environmental change

The arctic tundra and boreal forest were once considered the last frontiers on earth because of their vast expanses remote from agricultural land-use change and industrial development. These regions are now, however, experiencing environmental and social changes that are as rapid as those occurring anywhere on earth. This paper summarizes the role of northern regions in the global system and provides a blueprint for assessing the factors that govern their sensitivity to social and environmental change.     

Begging affects parental effort in the pied flycatcher, Ficedula hypoleuca

It has been suggested that nestlings use begging to increase their share of parental resources at the expense of current or future siblings. There is ample evidence that siblings compete over food with nestmates by begging, but only short-term effects of begging on parental provisioning rates have been shown. In this study, we use a new experimental design to demonstrate that pied flycatcher (Ficedula hypoleuca) nestlings that beg more are able to increase parental provisioning rates over the major part of the nestling period, thus potentially competing with future siblings. Parents were marked with microchips so that additional begging sounds could be played back when one of the parents visited the nest. By playing back begging sounds consistently at either male or female visits, a sex difference in provisioning rate that lasted for the major part of the nestling period was induced. If each parent independently adjusts its effort to the begging intensity of nestlings, begging may also be the proximate control mechanism for the sexual division of labour. Received: 24 January 1997 / Accepted after revision: 30 August 1997     

Temporal patterns in reproduction may explain variationin mating frequencies in the green-veined white butterfly Pieris napi

There is genetic variation in the female mating rate in the green-veined white butterfly (Pieris napi), and females benefit from male ejaculates that contain both sperm and accessory gland substances. Although polyandry corresponds to higher lifetime fecundity than monandry, some females abstain from remating irrespective of the number of available mates. Explaining genetic variation in mating rates requires that monandrous females perform better than polyandrous ones under some conditions. We experimentally explored the reproductive performance of females either with a low or high intrinsic mating rate by allowing them to mate, feed, and lay eggs freely in a laboratory. Individual females followed different life histories: during the early days of reproduction, females with a low mating rate produced more eggs than females with a high mating rate. Hence, refraining from the benefits of multiple mating may be beneficial, if the time for reproduction is limited, or other female traits associated with polyandry are traded off against longevity. Given the day length of 10 h, a model shows that even if polyandrous females enjoy higher lifetime reproductive success, changeable and unpredictable weather will favor monandry if each period of suitable weather lasts, on average, less than 5 days. Thus, a combination of life history cost and unpredictability of fitness may explain the maintenance of monandry in the wild. Our results are also consistent with the observation that frequency of monandry increases with latitude.