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The thermal response of maximum growth rate in morphology-based functional groups (MBFG) of freshwater phytoplankton is analysed. Contrasting an exponential Boltzmann-Arrhenius with a unimodal model, three main features were evaluated: (i) the activation energy of the rise ( E r ), (ii) the presence of a break in the thermal response and (iii) the activation energy of the fall ( E f ). The whole dataset ( N = 563) showed an exponential increase ( E r ∼ 0.5), a break around 24°C and no temperature dependence after the breakpoint ( E f = 0). Contrasting thermal responses among MBFG were found. All groups showed positive activation energy ( E r > 0), four showed no evidence of decline in growth rate (temperature range = 0-35°C) and two presented a breakpoint followed by a sharp decrease in growth rate. Our results evidenced systematic differences between MBFG in the thermal response and a coherent response significantly related to morphological traits other than size (i.e. within MBFG). These results provide relevant information for water quality modelling and climate change predictions., (© 2018 The Author(s).)

The Microcystis aeruginosa complex (MAC) clusters cosmopolitan and conspicuous harmful bloom-forming cyanobacteria able to produce cyanotoxins. It is hypothesized that low temperatures and brackish salinities are the main barriers to MAC proliferation. Here, patterns at multiple levels of organization irrespective of taxonomic identity (i.e. a trait-based approach) were analyzed. MAC responses from the intracellular (e.g. respiratory activity) to the ecosystem level (e.g. blooms) were evaluated in wide environmental gradients. Experimental results on buoyancy and respiratory activity in response to increased salinity (0-35) and a literature review of maximum growth rates under different temperatures and salinities were combined with field sampling from headwaters (800km upstream) to the marine end of the Rio de la Plata estuary (Uruguay-South America). Salinity and temperature were the major variables affecting MAC responses. Experimentally, freshwater MAC cells remained active for 24h in brackish waters (salinity=15) while colonies increased their flotation velocity. At the population level, maximum growth rate decreased with salinity and presented a unimodal exponential response with temperature, showing an optimum at 27.5°C and a rapid decrease thereafter. At the community and ecosystem levels, MAC occurred from fresh to marine waters (salinity 30) with a sustained relative increase of large mucilaginous colonies biovolume with respect to individual cells. Similarly, total biomass and, specific and morphological richness decreased with salinity while blooms were only detected in freshwater both at high (33°C) and low (11°C) temperatures. In brackish waters, large mucilaginous colonies presented advantages under osmotic restrictive conditions. These traits values have also been associated with higher toxicity potential. This suggest salinity or low temperatures would not represent effective barriers for the survival and transport of potentially toxic MAC under likely near future scenarios of increasing human impacts (i.e. eutrophication, dam construction and climate change)., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Toxic cyanobacterial blooms are globally increasing with negative effects on aquatic ecosystems, water use and human health. Blooms' main driving forces are eutrophication, dam construction, urban waste, replacement of natural vegetation with croplands and climate change and variability. The relative effects of each driver have not still been properly addressed, particularly in large river basins. Here, we performed a historical analysis of cyanobacterial abundance in a large and important ecosystem of South America (Uruguay river, ca 1900 km long, 365,000 km 2 basin). We evaluated the interannual relationships between cyanobacterial abundance and land use change, river flow, urban sewage, temperature and precipitation from 1963 to the present. Our results indicated an exponential increase in cyanobacterial abundance during the last two decades, congruent with an increase in phosphorus concentration. A sharp shift in the cyanobacterial abundance rate of increase after the year 2000 was identified, resulting in abundance levels above public health alert since 2010. Path analyses showed a strong positive correlation between cyanobacteria and cropland area at the entire catchment level, while precipitation, temperature and water flow effects were negligible. Present results help to identify high nutrient input agricultural practices and nutrient enrichment as the main factors driving toxic bloom formation. These practices are already exerting severe effects on both aquatic ecosystems and human health and projections suggest these trends will be intensified in the future. To avoid further water degradation and health risk for future generations, a large-scale (transboundary) change in agricultural management towards agroecological practices will be required., (© 2023 John Wiley & Sons Ltd.)

The Lotka–Volterra competition model (LVCM) is a fundamental tool for ecology, widely used to represent complex communities. The Allee effect (AE) is a phenomenon in which there is a positive correlation between population density and fitness, at low population densities. However, the interplay between the LVCM and AE has been seldom analyzed in multispecies models. Here, we analyze the mathematical properties of the LVCM + AE, investigating the coexistence of species interacting through neutral diffuse competition, their equilibria and stable points. Minimum viable population density arises as the threshold below which species go extinct, characteristic of strong Allee effects. Then, by imposing relationships of main parameters to body size, i.e. allometric scaling, we derive a general solution to the size-scaling maximum and minimum expected density under plausible scenarios. The scaling of maximum population density is consistent with the literature, but we also provide novel predictions on the scaling of the lower limit to population density, a critical value for conservation science. The resulting framework is general and yields results that increase our current understanding of how complex demographic processes can be linked to ubiquitous ecological patterns. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ornithology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pest outbreaks, harmful algal blooms and population collapses are extreme events with critical consequences for ecosystems. Therefore, understanding the ecological mechanisms underlying these extreme events is crucial. We evaluated theoretical predictions on the size scaling and variance of extreme population abundance by combining (i) the generalized extreme value (GEV) theory and (ii) the resource‐limited metabolic restriction hypothesis for population abundance. Using the phytoplankton data from the L4 station in the English Channel, we showed a negative size scaling of the expected value of maximal density, whose confidence interval included the predicted metabolic scaling (α = −1) supporting theoretical predictions. The role of resources and temperature in the distribution of the size–abundance pattern and residuals was well characterized by the GEV distribution. This comprehensive modelling framework will allow to elucidate community structure and fluctuations and provide unbiased return times estimates, thereby improving the prediction accuracy of the timing of the population outbreaks. [ABSTRACT FROM AUTHOR]

Copyright of Palabra Clave (1666-2938) is the property of Universidad Nacional de La Plata and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rate-temperature scaling relationships have fascinated biologists for nearly two centuries and are increasingly important in our era of global climate change. These relationships are hypothesized to originate from the temperature-dependent kinetics of rate-limiting biochemical reactions of metabolism. Several prominent theories have formalized this hypothesis using the Arrhenius model, which characterizes a monotonic temperature dependence using an activation energy E. However, the ubiquitous unimodal nature of biological temperature responses presents important theoretical, methodological, and conceptual challenges that restrict the promise for insight, prediction, and progress. Here we review the development of key hypotheses and methods for the temperature-scaling of biological rates. Using simulations, we examine the constraints of monotonic models, illustrating their sensitivity to data nuances such as temperature range and noise, and their tendency to yield variable and underestimated E, with critical consequences for climate change predictions. We also evaluate the behaviour of two prominent unimodal models when applied to incomplete and noisy datasets. We conclude with recommendations for resolving these challenges in future research, and advocate for a shift to unimodal models that better characterize the full range of biological temperature responses., (© 2024 The Authors. Ecology Letters published by John Wiley & Sons Ltd.)

The diversity of vascular patterns in flowers of Fabaceae subfamily Faboideae is outstanding yet remains relatively overlooked. Studies of floral vasculature are fairly scarce, and the phylogenetic framework they have been interpreted in is outdated. Here we propose a reassessment of previous results, underlining the relevance of vascular characters for systematic studies. A thorough literature survey was conducted, we bring some remarkable and seminal work from the late 1960s into light, and we include recent results leading to the description of an until now unrecognized floral vascular pattern in Faboideae. Our review shows that the high diversity of floral vasculature patterns among Faboideae is mostly due to the shape and number of traces, the vertical and horizontal fusions among bundles, and the mode of division of stamen traces. The distribution of the different vascular patterns in the phylogeny of the subfamily does not seem random, particularly at the tribal level. In addition, floral nectaries located between the stamens and the carpel exhibit contrasting vascular supplies in Faboideae. Morphological constraints might have an impact on the division mode of the traces of Faboideae flowers with numerous stamens. Our review provides groundwork for future studies aiming to clarify the nature of floral nectaries' structure and further investigate the evolution of floral vascular patterns in Faboideae using a representative taxonomic sampling and an updated phylogenetic framework. [ABSTRACT FROM AUTHOR]

Premise of research. The diversity of vascular patterns in flowers of Fabaceae subfamily Faboideae is remarkable yet remains somewhat overlooked. Here we propose an empirical examination of anatomical features of flowers of a selected group of Faboideae in which taxonomic delineation is currently being investigated in order to reassess the relevance of floral vascular characters for systematic studies. We focus on the New Caledonian endemic clade Arthroclianthus-Nephrodesmus , exhibiting contrasting flower morphologies. Methodology. Preanthetic floral buds of 6 of 17 species of the genera Arthroclianthus and Nephrodesmus were selected from herbarium specimens and a living tree. They were cut in serial transverse sections and studied with light microscopy. Pivotal results. We identify three vascular organizations in the Arthroclianthus-Nephrodesmus clade: the N. francii , A. sanguineus , and A. microbotrys patterns. The N. francii and A. sanguineus patterns both belong to the unihiate series. In the A. sanguineus and A. microbotrys patterns, the receptacle is vascularized by a similar number of traces, higher than in the N. francii pattern. We describe a very rare Faboideae vascular organization in A. microbotrys , the unihiate-dihiate series. Conclusions. The diversity of floral vascular anatomies shown by the Arthroclianthus-Nephrodesmus clade is the greatest among the 80 studied genera of Faboideae. Our results do not support the conservation of the current delineation of the two genera and are consistent with ongoing molecular investigations. The size of the flower organs could constrain vascular organization of the flowers, explaining the differences in the number of traces in the receptacle. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) are common in freshwater ecosystems and promote poor water quality. Toxins released by cyanobacteria affect animals and humans. Eutrophication is assumed to be one of the causes for the increase of HABs. Alternatively, bivalves can directly control phytoplankton biomass through filtration and nutrients excretion. However, these interaction remains less known about different bivalve species. Diplodon parallelopipedon (native to South America) is capable of consuming a wide range of particles by filter feeding and release nutrients available for phytoplankton. The aim of this study was to understand the role of the native bivalve D. parallelopipedon in phytoplankton dynamics. First, we compared grazing of 2 different food sources: (i) laboratory culture of Cryptomonas spp. (C) and (ii) wild populations of Microcystis aeruginosa complex (MAC). Both food sources were mixed to create a gradient of relative abundance expressed in % of MAC:C treatments: (1) 100 MAC, (2) 75:25, (3) 50:50, (4) 25:75, and (5) 100 C. Second, we studied nitrogen and phosphorus excretion rates displayed by D. parallelopipedon. Our results supported the hypothesis that D. parallelopipedon might favor the occurrence of MAC blooms by three mechanisms. On one hand, not being able to consume it when it is forming scums. Moreover, D. parallelopipedon actively consumed potential competitors. Finally, Diplodon potentially boosts MAC growth by nutrient releasing. [ABSTRACT FROM AUTHOR]

The Metabolic Theory of Ecology (MTE) predicts that the temperature increases exert a common effect on organisms stimulating metabolic rates, this being stronger for a heterotrophic than for an autotrophic metabolism. However, no available studies within the MTE framework have focused on organisms' response under fluctuation at high temperature interacting with factors such as nutrient availability, or how this interaction could affect the coexistence between mixotrophic and strict autotrophic phytoplankton. Hence, we assess how the phytoplankton metabolism and species composition are affected under scenarios of high temperature and fluctuation at high temperature, and how nutrients alter the direction and magnitude of such impact. For that, we use a mixed culture composed of two phytoplankton species: a strict autotrophic species and a mixotrophic species. Our results indicate that, in agreement with the MTE, only fluctuation at high temperature treatment registered a greater activation energy (Ea) value for respiration than for primary production and stimulated mixotrophic over strict autotrophic species abundance compared to control treatment. Remarkably, fluctuation at high temperature had a strong negative impact on the total abundance of the mixed-culture. The interaction between nutrient enrichment and fluctuation at high temperature increased abundance of the strict autotrophic species and overall species abundance, and led to Ea values that were higher in primary production than in respiration. Changes in community composition, enhanced by nutrient enrichment, could be behind this response, which can have implications in ecosystem functioning in a changing world. [ABSTRACT FROM AUTHOR]

The Vietnamese Mekong Delta is predicted to be one of the regions most impacted by climate change, causing increased temperature and salinity in inland waters. We hypothesized that the increase in temperature and salinity may impact the microcystin (MC) production of two Microcystis strains isolated in this region from a freshwater pond (strain MBC) and a brackish water pond (strain MTV). The Microcystis strains were grown at low (27 °C), medium (31 °C), high (35 °C) and extremely high (37 °C) temperature in flat photobioreactors (Algaemist). At each temperature, when cultures reached a stable state, sea salt was added to increase salinity to 4‰, 8‰, 12‰ and 16‰. MC concentrations and cell quota were reduced at high and extremely high temperatures. Salinity, in general, had comparable effects on MC concentrations and quota. At a salinity of 4‰ and 8‰, concentrations of MC per mL of culture and MC cell quota (based on chlorophyll, dry-weight and particle counts) were higher than at 0.5‰, while at the highest salinities (12‰ and 16‰) these were strongly reduced. Strain MBC produced five MC variants of which MC-RR and MC-LR were most abundant, followed by MC-YR and relatively low amounts of demethylated variants dmMC-RR and dmMC-LR. In strain MTV, MC-RR was most abundant, with traces of MC-YR and dmMC-RR only in cultures grown at 16‰ salinity. Overall, higher temperature led to lower MC concentrations and cell quota, low salinity seemed to promote MC production and high salinity reduced MC production. Hence, increased temperature and higher salinity could lead to less toxic Microcystis, but since these conditions might favour Microcystis over other competitors, the overall biomass gain could offset a lower toxicity. [ABSTRACT FROM AUTHOR]

Copyright of Innotec is the property of Laboratorio Tecnologico del Uruguay and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Innotec is the property of Laboratorio Tecnologico del Uruguay and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It is important to predict how phytoplankton will respond to global warming, as changes in their composition can affect ecosystem functions. We evaluated the effect of water warming on the taxonomic and functional composition of phytoplankton and on chemical characteristics that affect their occurrence, such as dissolved oxygen, pH and conductivity. Microcosms were constructed outdoors and monitored over time. The temperature was manipulated to simulate different scenarios predicted for the future. Warming caused a reduction in dissolved oxygen, while the pH and conductivity remained unchanged. We found a joint effect of temperature and time on chlorophyll-a as well as on the species and functional groups. The substitution of species and groups occurred in a similar way between treatments. However, a greater number of Cyanophyceae individuals were found at higher temperatures, while Bacillariophyceae and Euglenophyceae species were found more commonly in the lower warming treatments. These results indicate that warming altered the taxonomic and functional composition of phytoplankton, causing species substitution as well as a change in their functional characteristics, which led to the predominance of small organisms. Thus, contribute to predicting how an increase in temperature might alter the patterns of dominance, homogenization and community dynamics in future warming scenarios. [ABSTRACT FROM AUTHOR]

Phytoplankton size has an important functional role in ecosystem processes, such as nutrient production and cycling. It has been suggested that warmer temperatures may favor the smaller organisms in biological communities. We evaluate the mean size of the phytoplankton organisms and apply a morphology-based functional groups (MBFG) approach. We use time series of two floodplain lakes that present mean annual temperature difference of 10°C and similar hydrodynamic, area, and mean depth. We expected that a smaller mean size of MBFGs would be associated with higher temperatures. The Akaike Information Criterion was used to investigate environmental factors predicting the mean size of MBFGs within each lake. The mean size was most associated to nutrients and dissolved oxygen in the subtropical lake, and to temperature in the temperate lake. Large filaments with aerotopes and the small flagellated with siliceous exoskeletal structures showed high mean size at higher temperatures, thus contradicting temperature-size rules. Probably the high variability of mean size was provided by the high variability observed around environmental factors. Our findings reveal that other functional traits may be associated with the phytoplankters mean size, which result in adaptation to high variability of various environmental factors. [ABSTRACT FROM AUTHOR]

Iron availability in the Southern Ocean controls phytoplankton growth, community composition and the uptake of atmospheric CO2 by the biological pump. The KEOPS-2 (KErguelen Ocean and Plateau compared Study 2) "process study", took place around the Kerguelen Plateau in the Indian sector of the Southern Ocean. This is a region naturally fertilised with iron on the scale of hundreds to thousands of square kilometres, producing a mosaic of spring blooms which show distinct biological and biogeochemical responses to fertilisation. This paper presents biogeochemical iron budgets (incorporating vertical and lateral supply, internal cycling, and sinks) for three contrasting sites: an upstream high-nutrient low-chlorophyll reference, over the plateau and in the offshore plume east of the Kerguelen Islands. These budgets show that distinct regional environments driven by complex circulation and transport pathways are responsible for differences in the mode and strength of iron supply, with vertical supply dominant on the plateau and lateral supply dominant in the plume. Iron supply from "new" sources (diffusion, upwelling, entrainment, lateral advection, atmospheric dust) to the surface waters of the plume was double that above the plateau and 20 times greater than at the reference site, whilst iron demand (measured by cellular uptake) in the plume was similar to that above the plateau but 40 times greater than at the reference site. "Recycled" iron supply by bacterial regeneration and zooplankton grazing was a relatively minor component at all sites (< 8 % of new supply), in contrast to earlier findings from other biogeochemical iron budgets in the Southern Ocean. Over the plateau, a particulate iron dissolution term of 2.5 % was invoked to balance the budget; this approximately doubled the standing stock of dissolved iron in the mixed layer. The exchange of iron between dissolved, biogenic particulate and lithogenic particulate pools was highly dynamic in time and space, resulting in a decoupling of the iron supply and carbon export and, importantly, controlling the efficiency of fertilisation. [ABSTRACT FROM AUTHOR]

Iron availability in the Southern Ocean controls phytoplankton growth, community composition and the uptake of atmospheric CO2 by the biological pump. The KEOPS-2 experiment took place around the Kerguelen plateau in the Indian sector of the Southern Ocean, a region naturally fertilised with iron at the scale of hundreds to thousands of square kilometres, producing a mosaic of spring blooms which showed distinct biological and biogeochemical responses to fertilisation. This paper presents biogeochemical iron budgets (incorporating vertical and lateral supply, internal cycling, and sinks) for three contrasting sites: an upstream high-nutrient low-chlorophyll reference, over the plateau, and in the offshore plume east of Kerguelen Island. These budgets show that distinct regional environments driven by complex circulation and transport pathways are responsible for differences in the mode and strength of iron supply, with vertical supply dominant on the plateau and lateral supply dominant in the plume. Iron supply from "new" sources to surface waters of the plume was double that above the plateau and 20 times greater than at the reference site, whilst iron demand (measured by cellular uptake) in the plume was similar to the plateau but 40 times greater than the reference. "Recycled" iron supply by bacterial regeneration and zooplankton grazing was a relative minor component at all sites (< 8% of "new" supply), in contrast to earlier findings from other biogeochemical iron budgets in the Southern Ocean. Over the plateau, a particulate iron dissolution term of 2.5% was invoked to balance the budget; this approximately doubled the standing stock of dissolved iron in the mixed layer. The exchange of iron between dissolved, biogenic and lithogenic particulate pools was highly dynamic in time and space, resulting in a decoupling of iron supply and carbon export and, importantly, controlling the efficiency of fertilisation. [ABSTRACT FROM AUTHOR]

A robust, mild, and highly regioselective deacetylation of 1,2-diol diacetates in the presence of other acetate functions was achieved by using tetra- n-butylammonium fluoride. This method provided a single-step route to access O5′-acetyl ribonucleosides, a key intermediate in the synthesis of biomedically important nucleosides and nucleotides. Moreover, it offered the general applicability of a non-enzymatic method for the selective deacetylation of peracetylated 2′-deoxyribonucleosides. Its synthetic utility was further demonstrated by the synthesis of molecules of biomedical interest by using this particular deacetylation reaction. [ABSTRACT FROM AUTHOR]

The organic speciation of dissolved cobalt (DCo) was investigated in the subtropical region of the southeastern Atlantic, and in the Southern Ocean in the Antarctic Circumpolar Current (ACC) and the northern Weddell Gyre, between 34°25' S and 57°33' S along the Greenwich Meridian during the austral summer of 2008. The organic speciation of dissolved cobalt was determined by competing ligand exchange adsorptive cathodic stripping voltammetry (CLE-AdCSV) using nioxime as a competing ligand. The concentrations of the organic ligands (L) ranged between 26 and 73 pM, and the conditional stability constants (log K'CoL) of the organic complexes of Co between 17.9 and 20.1. Most dissolved cobalt was organically complexed in the water-column (60 to >99.9%). There were clear vertical and meridional patterns in the distribution of L and the organic speciation of DCo along the section. These patterns suggest a biological source of the organic ligands in the surface waters of the subtropical domain and northern subantarctic region, potentially driven by the cyanobacteria, and a removal of the organic Co by direct or indirect biological uptake. The highestL:DCo ratio (5.81 ± 1.07 pM pM-1) observed in these surface waters reflected the combined effects of ligand production and DCo consumption. As a result of these combined effects, the calculated concentrations of inorganic Co ([Co']) were very low in the subtropical and subantarctic surface waters, generally between 10-19 and 10-17 M. In intermediate and deep waters, the South African margins can be a source of organic ligands, as it was suggested to be for DCo (Bown et al., 2011), although a significant portion of DCo (up to 15%) can be stabilized and transported as in organic species in those DCo-enriched water-masses. Contrastingly, the distribution of L does not suggest an intense biological production of L around the Antarctic Polar Front where a diatom bloom had recently occurred. Here [Co'] can be several orders of magnitude higher than those reported in the subtropical domain, suggesting that cobalt limitation was unlikely in the ACC domain. The almost invariant L:DCo ratio of -1 recorded in these surface waters also reflected the conservative behaviours of both L and DCo. In deeper waters higher ligand concentrations were observed in waters previously identified as DCo sources (Bown et al., 2011). At those depths the eastward increase of DCo from the Drake Passage to the Greenwich Meridian could be associated with a large scale transport and remineralisation of DCo as organic complexes; here, the fraction stabilized as inorganic Co was also significant (up to 25%) in the low oxygenated Upper Circumpolar Deep Waters. Organic speciation may thus be a central factor in the biogeochemical cycle of DCo in those areas, playing a major role in the bioavailability and the geochemistry of Co. [ABSTRACT FROM AUTHOR]

Culture-independent molecular tools have been introduced into food microbiology during the last ten years. Most of them are based on the amplification of a bulk bacterial DNA extracted directly from a sample, the targeting of a selected gene, or a variable region of the selected gene. Many studies have explored indigenous lactic acid bacteria in dairy products by culture-independent molecular approaches. It is well known that indigenous microbiota significantly contribute to the uniqueness of artisanal cheeses. However, there is no molecular method that can provide complete qualitative and quantitative insight into the microbiota associated with a certain ecosystem. Therefore, a combination of molecular approaches should be applied to get a more objective picture of the microbiota. This paper aims to present the most widely used culture-independent molecular tools for identifying lactic acid bacteria in dairy products. [ABSTRACT FROM AUTHOR]

Presents the table of contents for the volume 38 of the December 1993 issue of "Scandinavian Journal of Immunology."

Peripheral blood leucocytes from 9 paucibacillary and 12 multibacillary leprosy patients, from 18 healthy controls and from 34 healthy leprosy contacts were stimulated with three mycobacterial heat shock proteins with respective molecular weights of 70,65 and 18 kDa and with the secreted 30-32 kDa protein, also called antigen 85. Antigen 85 was found to be the most powerful T-cell antigen (as measured by lymphoproliferation and IFN-γ secretion), eliciting a positive response in all (100%) paucibacillary patients and in all lepromin-positive controls and contacts. The three heat shock proteins (hsp) were less active T-cell stimuli. Reactivity to the 70 kDa hsp was found in only 44% of the paucibacillary patients, in 80% of the leprom in-positive controls and in 60% of the lepromin-positive leprosy contacts. The 65 kDa hsp stimulated T cells in 89% of the paucibacillary patients and in 80% of the lepromin-positive controls and contacts. Responsiveness to the 18 kDa hsp, finally, was clearly more frequent in tuberculoid leprosy patients (78%) than in lepromin-positive controls (40%) or lepromin-positive leprosy contacts (4%). T- cell reactivity of 8 lepromin-negative controls, of 9 lepromin-negative contacts and of 12 multibacillary leprosy patients was low to all the antigens tested. Although proliferative and IFN-γ responses were generally closely related, some subjects demonstrated a dissociation of these two immune parameters. Our data confirm previous findings on the powerful T-cell stimulatory properties of antigen 85 during M. leprae infection and suggest that this antigen is indeed a potentially protective T-cell immunogen. [ABSTRACT FROM AUTHOR]

Presents the table of contents for the August 1993 issue of the journal "Scandinavian Journal of Immunology."