Effect of Cross-Linking Waste Protein with Dialdehydes on Its Biodegradation Under Anaerobic Conditions

Most native polymers used in processing and application technologies are admittedly disposable from the environment in a biologic manner, but products possess low mechanical strength. One of the paths to increasing this attribute (if feasible) is their cross-linking, which may, however, affect their readiness to biodegradation. In the presented work this condition was observed on the example of waste protein (Hykol B) cross-linking by means of glutardialdehyde and glyoxal. Degree and course of cross-linking were determined through impedance spectroscopy. The objective of this work also was to obtain data for constructing a sensor capable of following the cross-linking course in real time, for potential industrial application of Hykol in continuous production. Impedance spectroscopy proved to be applicable even to this kind of material marked by considerable water content and exhibiting relatively high electric conductivity; so far it had been used only for materials of low conductivity. An aqueous environment inoculated with digested anaerobic sludge from a municipal wastewater treatment plant was selected for modeling anaerobic conditions. The relation was studied between cross-linking degree given by content of cross-linking agent (determined by impedance spectroscopy) and biodegradation degree under anaerobic conditions. It was confirmed that network density as given by quantity of added agent not only reduced breakdown degree but also slowed the course of the process. This fact is particularly obvious with cross-linking by means of glyoxal; network density is thus dependent on type of employed substance, which affect type and structure of created network. That not merely forms an obstacle during polymer swelling and dissolution but also prevents access of bacteria to source of metabolized organic carbon.     

Physiological responses to atmospheric fluorine pollution in transplants of Pseudoscleropodium purum

Transplants of the moss Pseudoscleropodium purum were placed under shade, and with an auto irrigation system, at five sites in the surroundings of an aluminium smelter to enable study of the possible effects of F on different physiological parameters after exposure periods of 28 and 56 days. Reference thresholds for the content of Chl a+b and for the pigment indexes of Chl a/b and D665/D665a were established with the data corresponding to 22 transplants of each duration of exposure, at seven sites where there was little or no contamination by F. The highest determination coefficients for the levels of F in moss were those obtained for chlorophyll content (Chl a+b) and the D665/D665a pigment index, with the effects being most evident in the transplants exposed to the contamination for 56 days.     

Reproductive success of monogamous and polygynous pied flycatchers (Ficedula hypoleuca)

One of the most interesting aspects of the mating system of pied flycatchers is the regular occurrence of polygyny. Here we present data on the reproductive success of polygynously paired pied flycatcher males compared to monogamous males based on paternity analyses through DNA fingerprinting. Males paired with two females suffered a higher loss in reproductive output per female compared to monogamous males due to (1) a greater proportion of unhatched eggs in their broods, (2) greater nestling mortality and (3) a greater probability of being cuckolded. Nevertheless, the number of fledglings was significantly greater for polygynous males. Based on the number of nestlings that returned for subsequent breeding seasons, however, the reproductive success of monogamous and polygynous males did not differ significantly. These data raise the question as to why males attempt polygyny. Received: 16 August 1999 / Received in revised form: 15 March 2000 / Accepted: 18 March 2000     

Assessing the Geographic Representativeness of Genebank Collections: the Case of Bolivian Wild Potatoes

Abstract: Genebank collection databases can be used for ecogeographical studies under the assumption that the accessions are a geographically unbiased sample. We evaluated the representativeness of a collection of wild potatoes from Bolivia and defined and assessed four types of bias: species, species-area, hotspot, and infrastructure. Species bias is the sampling of some species more often than others. Species-area bias is a sampling that is disproportionate to the total area in which a species is found. Hotspot bias is the disproportionate sampling of areas with high levels of diversity. Infrastructure bias is the disproportionate sampling of areas near roads and towns. Each of these biases is present in the Bolivian wild potato collection. The infrastructure bias was strong: 60% of all wild potato accessions were collected within 2 km of a road, as opposed to 22%, if collections had been made randomly. This analysis can serve as a guide for future collecting trips. It can also provide baseline information for the application of genebank data in studies based on geographic information systems.     

Effects of Habitat Fragmentation on Bird Species in a Relict Temperate Forest in Semiarid Chile

Abstract: We analyzed the structure and composition of a bird assemblage in a fragmented relict temperate forest located in northcentral Chile ( Fray Jorge National Park). In terms of species composition, the bird assemblage we found in Fray Jorge was more similar to southern temperate forest sites, located more than 1200 km south of Fray Jorge, than to localities found in nearby scrub habitats. The relict character and long-term isolation of the Fray Jorge forest provides a natural experiment with which to establish the potential long-term effects of fragmentation and isolation on southern Chilean temperate forests. Between May 1996 and March 1997, we conducted seasonal surveys of birds in six forest fragments, ranging in size from 0.5 to 22.5 ha, at Fray Jorge. The number of bird species at each forest fragment was positively correlated with fragment area during all seasons. The relict forest system had a steeper species-area slope than that reported for similar temperate-forest bird assemblages in forest fragments within Chiloé Island and for islands across the Chiloé Archipelago in southern Chile. In this regard, this bird fauna resembled a depauperate oceanic archipelago. This difference in area effects is likely a consequence of the minimization of rescue effects because of the absence of large source forest areas nearby and the long-term isolation of the system. In addition, the distribution of species among forest fragments in Fray Jorge was not random, showing a nested subset pattern. Thus, some species occur across all fragments, regardless of their area, and therefore are less affected by habitat fragmentation and less prone to local extinction. These results suggest that, for south-temperate forest birds, large fragments (or reserves) should afford better protection against extinction than small forest patches.     

Grazing rates of organic matter and living fungal biomass of decaying Spartina alterniflora by three species of salt-marsh invertebrates

 The pathway for the flow of salt-marsh grass production into marsh food-webs is still not well defined. We compared the abilities of three marsh macroinvertebrates [salt marsh periwinkles, Littoraria irrorata (Say) (=Littorina irrorata), salt-marsh coffee-bean snails, Melampus bidentatus (Say); and a talitrid amphipod, Uhlorchestia spartinophila Bounsfield and Heard] to access standing-dead leaves of smooth cordgrass (Spartina alterniflora Loisel). The invertebrates were incubated with naturally-decaying leaves, and the rates of removal of organic matter and living fungal biomass (ergosterol) were measured. The impact of invertebrate activity upon fungal growth rates was measured as rates of fungal-membrane synthesis (incorporation of radioacetate into ergosterol). The removal rates of organic leaf biomass per mg individual biomass were highest for amphipods (700 μg mg⁻¹ d⁻¹) and lowest for periwinkles (90 μg mg⁻¹ d⁻¹), but the relatively large biomass of the snails made their removal rates per individual greater than those of amphipods. Net removal of ergosterol by all three invertebrates was >50% for yellow-brown (early-decay) leaf blades. For fully-brown (advanced-decay) blades, >50% removal of ergosterol was found only for periwinkles; exposure to coffee-bean snails and amphipods resulted in a net ergosterol reduction of ≤20%. The lower net reduction of living fungal biomass by coffee-bean snails and amphipods may have been due to fungal-growth stimulation (2.3-fold stimulation in coffee-bean snails and 1.5-fold stimulation in amphipods). Grazing by periwinkles did not stimulate fungal growth, possibly because of its high intensity. Grazing by these three salt-marsh shredders may affect marsh-grass shoot-decay in different ways. Periwinkles may abbreviate the period of fungal production, and incorporate the decaying material relatively quickly into snail biomass and fecal-pellet rain to the sediments. Coffee-bean snails and amphipods may enhance and prolong fungal production, along with the formation of fecal-pellet rain. All three invertebrates fed preferentially on leaf blades rather than leaf sheaths, and feeding rates of gastropods were higher during the night than during the day. Received: 25 November 1998 / Accepted: 4 November 1999     

Spawning behaviour and sex hormone levels in adult and precocious brown trout (Salmo trutta L.) males and the effect of anosmia

Summary. In the present experiment the behaviour and endocrine status of males of the brown trout, Salmo trutta L., (Salmoniformes: Salmonidae) were studied when males were kept in a stream tank with a nest digging female. Groups of mature adult males and precocious intact or anosmic male parr were placed with the nesting female so that the group resembled a natural spawning situation with big anadromous fish acting as dominant males and precocious parr acting as “sneakers”. A control experiment was also run with only males without a female present. In intact parr there were significant positive correlations between the per cent of the total observation time spent with a female, milt volume, and plasma concentration of 17α, 20β-dihydroxy-4-pregnen-3-one. Anosmic parr had significantly lower volumes of strippable milt and gonadal steroid hormone levels compared with intact parr. However, no differences were found in the control experiment. Significantly fewer anosmic parr attended and courted the nesting female and those anosmic fish that attended the female had significantly lower plasma levels of gonadal hormones. Intact parr also displayed a greater number of agonistic acts against other parr without any difference in fighting ability. No differences in aggression occured in the control experiment. In adult males together with a female, post-experimental gonadal steroid hormone levels were higher than pre-experimental levels. Positive correlations between aggression and androgen hormone levels were observed in adult males. No differences in plasma hormone levels were observed between adult males and intact precocious males. The results show that olfactory occlusion results in low steroid hormone levels and milt volumes in precocious males placed in a spawning situation. The courting behaviour was also affected by anosmia. Odours from the nesting female may have caused the enhanced plasma hormone levels and stimulated the males to attend the female. Received 15 May 1997; accepted 29 June 1997.     

Semi-parametric statistical approaches for space-time process prediction

The problem of estimation and prediction of a spatial-temporal stochastic process, observed at regular times and irregularly in space, is considered. A mixed formulation involving a non- parametric component, accounting for a deterministic trend and the effect of exogenous variables, and a parametric component representing the purely spatio-temporal random variation is proposed. Correspondingly, a two-step procedure, first addressing the estimation of the non- parametric component, and then the estimation of the parametric component is developed from the residual series obtained, with spatial-temporal prediction being performed in terms of suitable spatial interpolation of the temporal variation structure. The proposed model formula-tion, together with the estimation and prediction procedure, are applied using a Gaussian ARMA structure for temporal modelling to space-time forecasting from real data of air pollution concentration levels in the region surrounding a power station in northwest Spain.