Effects of Some Chemicals on the Oxygen Evolution and Oxygen Uptake in Isolated Wheat Chloroplasts Irradiated without the Addition of an Oxidant

The oxygen exchange, obtained when isolated chloroplasts of Triticum aestivum, wheat, are irradiated without the addition of a Hill oxidant has been investigated using an oxygen electrode. Ascorbate, catalase, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone(DBMIB), diethyldithio-carbamate (DEDT), dichlorophenylmethylurea (DCMU), and potassium cyanide were added to the Chloroplasts in order to investigate the oxygen exchange. At least two oxygen uptake reactions, one sensitive to catalase and one catalase-insensitive, appeared upon irradiation. Hydrogen peroxide was the product of the oxygen uptake in the former process, and water was the reductant. The formation of hydrogen peroxide was probably associated with photosystem I. The other oxygen consuming reaction was found to be insensitive to both catalase and potassium cyanide. After the chloroplasts had been treated with DCMU, it was possible to show that the catalase-insensitive oxygen uptake was localized in photosystem I, and that a cyclic electron transport system or some endogenous reductant (-s) acted in the oxygen uptake. Addition of ascorbate or DEDT to the chloroplasts led to an enhanced oxygen uptake in 710 nm light. This was probably due to the effect of these compounds on the superoxide radical ion formed in photosystem I. The stimulated oxygen uptake was only weakly affected by catalase, indicating that hydrogen peroxide was not a product of this oxygen uptake. Addition of DEDT and potassium cyanide inhibited (strongly respectively weakly) the oxygen uptake when photosystem II was functioning. The effect of these compounds was probably due to an inhibition of the electron transport at the plastocyanin. DBMIB inhibited the oxygen uptake reactions and the cooperation between the two photosystems. The cooperation between the photosystems was also studied in DCMU-treated chloroplasts. The reactions in photosystem II, measured as oxygen evolution, were more inhibited than the coupling between the photosystems. The oxygen “gush” appearing upon irradiation in light of 650 nm was not affected by a DBMIB-treatment, showing that the oxygen evolution was due to the reduction of plastoquinone. The reoxidation in the dark of the plastoquinone pool was stimulated by DBMIB and potassium cyanide indicating that an oxygen uptake could be associated with plastoquinone. The sites of interaction of oxygen with the electron transport pathways in chloroplasts, and the different reductants for the oxygen consuming reactions are discussed.     

Four new interstitial species of marine Oligochaeta representing a new family

A new oligochaete family, Randiellidae, is established for R. multitheca sp.n. (from the continental shelf off the east coast of the U.S.A.), R. litoralis sp.n. (from Oregon, U.S.A.), R. caribaea sp.n. and R. minuta sp.n. (both from Guadeloupe and Martinique), all members of a new marine genus Randiella. The species are characterized by small single-pointed and somewhat sigmoid somatic setae, slender (generally hair-like) modified genital setae in segment X, sperm funnels in X (if one pair), or in X and XI (if two pairs), very simple male ducts lacking atria, clitellum over XII-XIII, and multiple spermathecae in VII and/or VIII.     

Inanidrilus bulbosus gen. et sp.n., a Marine Tubificid (Oligochaeta) from Florida, USA

Inanidrilus bulbosus gen. et sp.n. is described from subtidal sands near Miami, Florida. The species lacks alimentary canal, but it possesses highly modified penial setae and an unpaired dorsal spermatheca. It appears closely related to Phallodrilus Pierantoni, but since it is devoid of anterior prostate glands, which are attached to the ental ends of the atria in Phallodrilus , a new monotypic genus, Inanidrilus gen.n., is established.     

Resource quality and stoichiometric constraints on stream ecosystem functioning

1. Resource quality and stoichiometric imbalances in carbon : nutrient ratios between consumers and resources can influence key ecosystem processes. In many streams, this has important implications for food webs that are based largely upon the utilization of terrestrial leaf‐litter, which varies widely among litter types in its value as a food source for detritivores and as a substrate for microbial decomposers. 2. We measured breakdown rates and macroinvertebrate colonization of leaf‐litter from a range of native and exotic plants of differing resource quality and palatability to consumers [e.g. carbon : nitrogen : phosphorus (C : N : P) ratios, lignin and cellulose content], in a field experiment. We also measured C : N : P ratios of the principal leaf‐shredding invertebrates, which revealed strong stoichiometric imbalances across trophic levels: C : N and C : P ratios typically differed by at least one order of magnitude between consumers and resources, whereas N : P imbalances were less marked. Application of the threshold elemental ratio approach, which integrates animal bioenergetics and body elemental composition in examining nutrient deficiency between consumers and resources, revealed less marked C : P imbalances than those based on the simpler arithmetic differences described above. 3. Litter breakdown rates declined as nutrient imbalances widened and resource quality fell, but they were independent of whether resources were exotic or native. The principal drivers of total, microbial and invertebrate‐mediated breakdown rates were lignin : N, lignin : P and fungal biomass, respectively. However, multiple regression using orthogonal predictors yielded even more efficient models of litter breakdown, as consumers responded to more than one aspect of resource quality. For example, fungal biomass and litter C : N both influenced invertebrate‐mediated breakdown. 4. Large stoichiometric imbalances and changes in resource quality are likely to have serious consequences for stream ecosystem functioning, especially when riparian zones have been invaded by exotic plant species whose chemical composition differs markedly from that of the native flora. Consequently, the magnitude and direction of change in breakdown rates and, thus, resource depletion, will be driven to a large extent by the biochemical traits (rather than taxonomic identity per se) of the resident and invading flora.     

Parakaketio longiprostatus gen. et sp.n., a Marine Tubificid (Oligochaeta) from Florida, U.S.A.

Parakaketio longiprostatus sp.n. is described from shallow marine water in S.E. Florida. The male ducts of the new genus Parakaketio resemble those of Kaketio Righi & Kanner, 1979, but do not end as voluminous, eversible pseudopenes, rather as simple tubes opening directly to the exterior through simple pores.     

Predicting Outcome on Admission and Post-Admission for Acetaminophen-Induced Acute Liver Failure Using Classification and Regression Tree Models

Background/Aim

Assessing prognosis for acetaminophen-induced acute liver failure (APAP-ALF) patients often presents significant challenges. King’s College (KCC) has been validated on hospital admission, but little has been published on later phases of illness. We aimed to improve determinations of prognosis both at the time of and following admission for APAP-ALF using Classification and Regression Tree (CART) models.

Methods

CART models were applied to US ALFSG registry data to predict 21-day death or liver transplant early (on admission) and post-admission (days 3-7) for 803 APAP-ALF patients enrolled 01/1998–09/2013. Accuracy in prediction of outcome (AC), sensitivity (SN), specificity (SP), and area under receiver-operating curve (AUROC) were compared between 3 models: KCC (INR, creatinine, coma grade, pH), CART analysis using only KCC variables (KCC-CART) and a CART model using new variables (NEW-CART).

Results

Traditional KCC yielded 69% AC, 90% SP, 27% SN, and 0.58 AUROC on admission, with similar performance post-admission. KCC-CART at admission offered predictive 66% AC, 65% SP, 67% SN, and 0.74 AUROC. Post-admission, KCC-CART had predictive 82% AC, 86% SP, 46% SN and 0.81 AUROC. NEW-CART models using MELD (Model for end stage liver disease), lactate and mechanical ventilation on admission yielded predictive 72% AC, 71% SP, 77% SN and AUROC 0.79. For later stages, NEW-CART (MELD, lactate, coma grade) offered predictive AC 86%, SP 91%, SN 46%, AUROC 0.73.

Conclusion

CARTs offer simple prognostic models for APAP-ALF patients, which have higher AUROC and SN than KCC, with similar AC and negligibly worse SP. Admission and post-admission predictions were developed.

Key Points

• Prognostication in acetaminophen-induced acute liver failure (APAP-ALF) is challenging beyond admission• Little has been published regarding the use of King’s College Criteria (KCC) beyond admission and KCC has shown limited sensitivity in subsequent studies• Classification and Regression Tree (CART) methodology allows the development of predictive models using binary splits and offers an intuitive method for predicting outcome, using processes familiar to clinicians• Data from the ALFSG registry suggested that CART prognosis models for the APAP population offer improved sensitivity and model performance over traditional regression-based KCC, while maintaining similar accuracy and negligibly worse specificity• KCC-CART models offered modest improvement over traditional KCC, with NEW-CART models performing better than KCC-CART particularly at late time points     

A generic revision of the Phallodrilinae (Oligochaeta, Tubificidae)

The generic classification of the subfamily Phallodrilinae (with a total of 252 species) is revised according to phylogenetic principles. Morphological character patterns are assessed under the principle of maximum parsimony, but due to the poor resolution and instability in the resulting cladograms, the analysis is supplemented with intuitive weighting of synapomorphic similarities. Thirty-one genera are recognized. The former definition of the type genus Phallodrilus Picrantoni, 1902, is revised and the members of this genus are reclassified into 20 taxa, each hypothesized to be monophyletic: Phallodrilus s.str . (revised to contain the type species only), Somalidrilus gcn.n., Milliganius gen.n., Phallodriloides gen.n., Albanidrilus gen.n., Abyssidrilus gen.n., Paraktedrilus gen.n., Uniporodrilus Erséus, 1979, Inermidrilus gen.n., Gianius gen.n., Mexidrilus gen.n., Peosidrilus Baker & Erséus, 1979, Atlantidrilus Erséus, 1983, Thalassodrilus Brinkhurst, 1963, Pirodrilus gen.n., Pirodriloides gen.n., Marionidrilus gen.n., Pectinodrilus gen.n., Pacifidrilus gen.n. and Pseudospiridion gen.n. Nine new species are described from the Northwest Atlantic: Phallodriloides pinnulatus sp.n., Abyssidrilus opulentus sp.n., A. potens sp.n., A. altoides sp.n., Mexidrilus obtusus sp.n., Peosidrilus dalei sp.n., P. aduncus sp.n., P. riseri sp.n., and Atlantidrilus hamulus sp.n. The genus Discordiprostatus Baker, 1982, is synonymized with Nootkadrilus Baker, 1982.     

Chlorophyll Composition in an Isolated Chlorophyll a-Protein Complex of Photosystem I

A P700-chlorophyll a-protein complex, solubilized by the detergent Triton X-100, has been isolated by hydroxyl apatite column chromatography. The chlorophyll composition was determined by thin-layer chromatography and spectrofluorimetric analysis. This photosystem I reaction centre complex, prepared at pH 7, contained pheophytin a and P700 in a ratio of 2/1, high enough to account for a composition similar to that in the reaction centre of photosynthetic bacteria. Prepared at pH 9, the same ratio was 0.2/1, which excludes pheophytin a from having the same function as that of bacterio-pheophytin in the photosynthetic bacteria.     

Evaluation of the Inheritance of the Complex Vertebral Malformation Syndrome by Breeding Studies

To investigate the congenital complex vertebral malformation syndrome (CVM) in Holstein calves, two breeding studies were performed including 262 and 363 cows, respectively. Cows were selected from the Danish Cattle Database based on pedigree and insemination records. Selected cows were progeny of sires with an established heterozygous CVM genotype and pregnant after insemination with semen from another sire with heterozygous CVM genotype. Following calving the breeders should state, if the calf was normal and was requested to submit dead calves for necropsy. In both studies, significantly fewer CVM affected calves than expected were obtained; a finding probably reflecting extensive intrauterine mortality in CVM affected foetuses. The findings illustrate increased intrauterine mortality as a major potential bias in observational studies of inherited disorders.