Pattern of cercarial emergence of Schistosoma curassoni from Niger and comparison with three sympatric species of schistosomes.

The emergence pattern of Schistosoma curassoni cercariae from Bulinus umbilicatus, whose adult worms parasitize bovine, caprine, and ovine ungulates in Niger, is of a circadian type with a mean emission time at 0855 hr +/- 1 hr 6 min, characteristic of the schistosome species parasitizing domestic or wild cattle. The comparison of this cercarial emergence pattern with those of the other 3 sympatric species of schistosomes (Schistosoma haematobium, Schistosoma bovis, and Schistosoma mansoni) shows a significant difference between the chronobiology of the cercariae infective for human and those infective for bovine hosts. This difference may improve epidemiological surveys based on snail prevalences by allowing the distinction between bulinids infected with human and bovine parasites.     

Leishmaniasis in Bolivia. IV. The dog in the cycles of leishmaniasis in Bolivia

In Bolivia, the dog is involved in the cycle of visceral leishmaniasis (Leishmania (Le.) chagasi) in the Yungas (alt. 1,000-2,000 m), and also in the cycle of cutaneous leishmaniasis (Le. (V.) braziliensis) in the Alto Beni (alt. 400-600 m). But it plays a different role in the two cycles. In the Yungas focus, it is the main reservoir of Le. (Le.) chagasi and the source of contamination for man. In the Alto Beni focus, it is only a "victim-host", like man, of Le. (V.) braziliensis; the reservoir of which is unknown. Wild mammals are very likely to be involved.     

Studies on haemosiderin and ferritin from iron-loaded rat liver

Summary Haemosiderin has been isolated from siderosomes and ferritin from the cytosol of livers of rats iron-loaded by intraperitoneal injections of iron-dextran. Siderosomal haermosiderin, like ferritin, was shown by electron diffraction to contain iron mainly in the form of small particles of ferrihydrite (5Fe₂O₃ · 9H₂O), with average particle diameter of 5.36±1.31 nm (SD), less than that of ferritin iron-cores (6.14±1.18 nm). Mössbauer spectra of both iron-storage complexes are also similar, except that the blocking temperature,T _B, for haemosiderin (23 K) is lower than that of ferritin (35 K). These values are consistent with their differences in particle volumes assuming identical magnetic anisotropy constants. Measurements of P/Fe ratios by electron probe microanalysis showed the presence of phosphorus in rat liver haemosiderin, but much of it was lost on extensive dialysis. The presence of peptides reacting with anti-ferritin antisera and the similarities in the structures of their iron components are consistent with the view that rat liver haemosiderin arises by degradation of ferritin polypeptides, but its peptide pattern is different from that found in human-thalassaemia haemosiderin. The blocking temperature, 35 K, for rat liver ferritin is near to that reported, 40 K, for human-thalassaemia spleen ferritin. However, the haemosiderin isolated from this tissue, in contrast to that from rat liver, had aT _B higher than that of ferritin. The iron availability of haemosiderins from rat liver and human-thalassaemic spleen to a hydroxypyridinone chelator also differed. That from rat liver was equal to or greater, and that from human spleen was markedly less, than the iron availability from either of the associated ferritins, which were equivalent. The differences in properties of the two types of haemosiderin may reflect their origins from primary or secondary iron overload and differences in the duration of the overload.     

Immunohistochemical demonstration of catecholaminergic cell bodies in the spinal cord of the rat

Summary In order to elucidate the anatomy of the spinal dopaminergic system, an immunohistochemical study using a tyrosine-hydroxylase (TH) antibody was undertaken in the rat. Intracisternal 6-hydroxydopamine (6-OHDA) injections were administered to destroy most of the noradrenergic fibres that descende to the spinal cord while preserving the dopaminergic fibres. The density of the remaining TH-like immunoreactive fibres was relatively low at all levels of the spinal cord; the highest density was observed in layers III, IV and X. In addition, we report the first evidence for the existence of TH-like immunoreactive cell bodies at definite levels (especially sacral) of the spinal cord.     

Operation of the glycolate pathway in isolated bundle sheath strands of maize and Panicum maximum

Operation of the glycolate pathway in isolated bundle sheath (BS) strands of two C₄ species was demonstrated from ¹⁴C incorporation into two intermediates, glycine and serine, under conditions favourable for photorespiratory activity. Isolated BS strands fixing ¹⁴CO₂ under light at physiological rates incorporate respectively 3% (Zea mays L., cv. INRA 258) and 7% (Panicum maximum Jacq.) of total ¹⁴C fixed into glycine + serine, at low bicarbonate levels (less than the Km for CO₂ fixation, 0.8 mM). Higher bicarbonate concentrations depressed the percentage of incorporation into the two amino acids. No labelling was observed in the absence of added glutamate. Oxygen was required for glycine + serine labelling, since ¹⁴C incorporation into glycine was largely depressed by argon flushing, and labelling of the two amino acids was nearly suppressed by the addition of the strong reductant, dithionite, especially in maize. Two inhibitors of the glycolate pathway were tested. With α-hydroxypyridine-methanesulfonic acid, an inhibitor of glycolate oxidase, labelling of glycine and serine remained minimal whereas glycolate was accumulated. Isoniazid, an inhibitor of the transformation of glycine to serine induced a 50% increased labelling of glycine in maize BS, and a large decrease in serine labelling. In Panicum, the increase in [¹⁴C]-glycine was 90%. These results suggest that the pathway glycolate → glycine → serine operates in these plants. However, leakage of metabolites occurs in BS cells, especially in maize and a large part of newly formed glycolate, glycine and serine is exported out of the cells. Operation of ribulose-1,5-bisphosphate oxygenase activity in competition with ribulose-1,5-bisphosphate carboxylase is demonstrated by the lowering of total ¹⁴CO₂ fixation when O₂ is increased at low bicarbonate concentration. An interesting feature observed in maize BS, at low bicarbonate concentration, was an increase in ribulose-1,5-bisphosphate labelling when the O₂ level was decreased. This was accompanied by an increase in CO₂ fixation. This could indicate an increased rate in synthesis of ribulose-1,5-bisphosphate (which accumulated) due to a stimulation of ATP synthesis by cyclic photophosphorylation under anaerobic conditions.     

Evidence for the Predator Attraction Hypothesis in an amphibian predator–prey system

Many species possess damage-released chemical alarm cues that function in alerting nearby individuals to a predator attack. One hypothesis for the evolution and/or maintenance of such cues is the Predator Attraction Hypothesis, where predators, rather than prey, are the “intended” recipients of these cues. If a predator attack attracts additional predators, these secondary predators might interfere with the predation event, providing the prey with a better chance to escape. In this study, we conducted two experiments to explore this hypothesis in an amphibian predator/prey system. In Experiment 1, we found that tiger salamanders (Ambystoma mavortium) showed a foraging attraction to chemical cues from wood frog (Lithobates sylvaticus) tadpoles. Salamanders that were experienced with tadpole prey, in particular, were strongly attracted to tadpole alarm cues. In Experiment 2, we observed experimental encounters between a tadpole and either one or two salamanders. The presence of the second predator caused salamanders to increase attack speed at the cost of decreased attack accuracy (i.e., increasing the probability that the tadpole would escape attacks). We also found that the mere presence of visual and chemical cues from a second predator did not affect this speed/accuracy trade-off but did cause enough of a distraction to increase tadpole survival. Thus, our findings are consistent with the Predator Attraction Hypothesis for the evolution and/or maintenance of alarm cues.     

Developing Regenerate: A circular economy engagement tool for the assessment of new and existing buildings

The transition toward a circular economy (CE) is key in decarbonizing the built environment. Despite this, knowledge of—and engagement with—CE philosophies remains limited within the construction industry. Discussion with practitioners reveals this to be contributed to by a lack of clarity regarding CE principles, with numerous organizations recommending implementation of differing and sometimes conflicting principles. In addition, a systematic assessment of how building designs consider CE is made difficult by the multiple design areas required to be considered and the large amount of design data required to do so. The absence of a systematic CE assessment causes a lack of comparability across designs, preventing benchmarking of CE practices in building design at present. This paper details the development of Regenerate, a CE engagement tool for the assessment of new and existing buildings, established in an effort to overcome the aforementioned barriers to the adoption of CE within the construction sector. A CE design workflow for the built environment is proposed, comprising four overarching circularity principles (Design for Adaptability; Design for Deconstructability; Circular Material Selection; Resource Efficiency) and contributing design actions. In addition to engaging stakeholders by enabling the assessment of building designs, the tool retrieves key data for further research. Information on completed design actions as well as recycling and waste metrics is collected to facilitate future CE benchmarking. “Bill of materials” data (i.e., material quantities) is also compiled, with this being key in material stock modeling research and embodied carbon benchmarking.     

Environment outweighs the effects of fishing in regulating demersal community structure in an exploited marine ecosystem

Global climate change has already caused bottom temperatures of coastal marine ecosystems to increase worldwide. These ecosystems face many pressures, of which fishing is one of the most important. While consequences of global warming on commercial species are studied extensively, the importance of the increase in bottom temperature and of variation in fishing effort is more rarely considered together in these exploited ecosystems. Using a 17 year time series from an international bottom trawl survey, we investigated covariations of an entire demersal ecosystem (101 taxa) with the environment in the Celtic Sea. Our results showed that over the past two decades, biotic communities in the Celtic Sea were likely controlled more by environmental variables than fisheries, probably due to its long history of exploitation. At the scale of the entire zone, relations between taxa and the environment remained stable over the years, but at a local scale, in the center of the Celtic Sea, dynamics were probably driven by interannual variation in temperature. Fishing was an important factor structuring species assemblages at the beginning of the time series (2000) but decreased in importance after 2009. This was most likely caused by a change in spatial distribution of fishing effort, following a change in targeted taxa from nephrops to deeper water anglerfish that did not covary with fishing effort. Increasing bottom temperatures could induce additional changes in the coming years, notably in the cold‐water commercial species cod, hake, nephrops, and American plaice. We showed that analyzing covariation is an effective way to screen a large number of taxa and highlight those that may be most susceptible to future simultaneous increases in temperature and changes in exploitation pattern by fisheries. This information can be particularly relevant for ecosystem assessments.