Lung pathogenesis. III. The immunopathogenic component of pulmonary processes (a systemic approach)

The pathogenetic role of hypersensitivity reactions was systemically approached in the framework of chronic lung processes. There were analysed the biphasic evolution at least of this activity (sensitization, hypersensitivity reactions, immunopathogenic mechanisms and the morphological events induced by them having or not an immune significance); these events occurring during the stereotyped dynamics of lung processes, are often repeated, and modify the pre-existing lesions, contributing to the complication and self-perpetuation of lung processes.     

Lung pathogenesis. IV. Persisting pathogens and accumulative-proliferative cellular reactions in chronic lung processes (a systemic approach)

Persistence of pathogens within lung structures is due to the co-operation of the impairment of local defence means, of the aerial concentration and of the immunopathogenic component of processes. The action of pathogens, analysed in the framework of factor assemblies determining the process sequences, induced, as the most frequent reaction, cell proliferation and accumulation with the insertion of chemotactically retained circulating cells and their homing within alveolar wall interstitia and peribronchovascular sheets. The relations between the different inserting cells and the local ones are analyzed, with emphasis upon the derepression of local mechanisms of the steady state, secondary proliferation of both local and newly inserted cells, and current evolution to fibrosis.     

Lung pathogenesis. V. The stereotype development of bronchial and lobular pathological reactions (a systemic approach)

Taking into account the present data upon the general stereotyping of different pathological processes of various nature challenged by the extremely numerous environmental actions, a structural analysis of the peculiarities presented by such reactions at the lung level, mainly on bronchial and lobular structures, was attempted. It was shown that the first damaged structures and their behaviour impose the peculiarities of the subsequently developed reactions which manifest a certain stereotyping, different when bronchi or lobules are the first lesioned. Relationships between bronchial and lobular lesions were also analysed and pointed out their role in the development of the whole complex process of the lung. This special aspect of lung complex pathogenesis was also emphasized.     

The pathological process. III(IV). Cellular population systems as substrates of pathological processes: structure, reactivity, dynamics and basic lesions

This fourth paper dealt with the analysis of cellular population systems as the main substrates of pathological processes. The analysis pointed out the reactivity of these systems, their histogenesis and dynamics, their cellular composition and reactional capacity of composing cells, the relations between different groups of cells forming the system (intrasystemic relationships), those between proliferation and differentiation-maturation, the multifactorial determinism of proliferation, differentiation, maturation and mobilization of the cells composing the system. The analysis of basic lesions of cellular population systems (cellular hypertrophy, cell hyperplasia, metaplasia and neoplastic transformation) completed this dynamic investigation.     

On the increase in complexity in evolution II. The relativity of complexity and the principle of minimum increase

The complexity of a system cannot be measured in absolute terms, but only relative to a specified observer. As a result, the operational definition of complexity will be different for different sorts of systems and problems. In many cases it will not be as a real valued function.For the study of evolution we adopt as our definition the information content of the instructions required to build the system. Because we take into account factors such as the properties of the epigenetic system and the laws of physics and chemistry, this is not the same as the information content of the genome as measured in terms of codon or amino acid frequencies. Using this definition, we derive a principle of minimum increase in complexity, and we apply it to explain two well-known phenomena in evolution, Williston's law and parallelism. It is unlikely that any definite trends in the evolution of complex systems can be accounted for by simple optimization principles such as the law of natural selection, as these contain no arrow of time.     

Immunohistochemical demonstration of carbonic anhydrase isoenzyme VI (CA VI) expression in rat lower airways and lung.

Carbonic anhydrase isoenzyme VI (CA VI), which is transported in high concentrations in saliva and milk into the alimentary tract, is an important element of mucosal protection in the upper alimentary tract. Like alimentary tract mucosa, the respiratory tract mucosa is also exposed to heavy microbial, physical, and chemical stress. The protective and renewal-promoting factors present in the surface mucus of the respiratory tract are mainly produced by the seromucous tracheobronchial glands. Here we studied the secretion of CA VI by these glands in adult and developing rats using immunohistochemical techniques. The serous acinar and duct cells of the tracheobronchial glands stained for CA VI. The presence of the enzyme also in the duct content indicates its active secretion into the surface mucus. CA VI was also visible in the secretory cells and at the base of the ciliated cells of the tracheobronchial surface epithelium. Moreover, the Clara cells of the bronchiolar surface epithelium stained for CA VI. These findings are consistent with the hypothesis that CA VI has a mucosa-protective role not only in the gastrointestinal tract but also in the respiratory tract, where CA VI may act as a pivotal pH neutralizer and growth factor.     

The role of superoxide radical in chromium (VI)-generated hydroxyl radical: the Cr(VI) Haber-Weiss cycle.

To understand the role of the superoxide (O-2) radical in chromate-related genotoxicity, we investigated whether Cr(VI) can catalyze the Haber-Weiss cycle in vitro: O-2 + Cr(VI)----Cr(V) + O2 Cr(V) + H2O2----Cr(VI) + .OH + OH-. ESR and spin trapping techniques were utilized to monitor the O-2 (produced using xanthine/xanthine oxidase), .OH, and Cr(V) species. Superoxide dismutase as well as catalase inhibited the .OH radical radical formation, attesting to the direct involvement of O-2 and H2O2 in the process. ESR measurements also provided direct evidence for the formation of Cr(V). Kinetic measurements were consistent with the role of Cr(V) and H2O2 as intermediates in .OH formation. These results indicate that in cellular media, especially during chromate phagocytosis, the O-2 radical can become a significant source of .OH radicals and hence a significant factor in the biochemical mechanism of cellular damage due to Cr(VI) exposure.     

Activated dynamics and timescale separation within the landscape paradigm: signature of complexity, diversity and glassiness

The landscape paradigm has become a widespread picture within the realm of complex systems. Complex systems include a great variety of systems, ranging from glasses to biopolymers, which display a common dynamical behavior. Within this framework, the dynamics of a such a system can be envisioned as the search it performs on its (potential energy) landscape. This approach rests on the belief that the relaxation behavior depends only on generic features, irrespective of specific details and lies on the validity of a timescale separation scenario computationally corroborated but not properly validated yet form first principles. In this work we shall show that the prevalence of activated dynamics over other kinds of mechanisms determines the emergence of complex dynamical behavior. Thus, complexity and diversity are not intrinsic properties of a system but depend on the kind of exploration of the landscape. We shall focus mainly on an ample generic context (complex hierarchical systems which have been used as models of glasses, spin glasses and biopolymers) and a specific one (model glass formers). For the last case we shall be able to reveal (in mechanistic terms) the microscopic rationale for the occurrence of timescale separation. Furthermore, we shall explore the connections between these two up to now mostly unrelated contexts and the relation to a variational principle, and we shall reveal the conditions for the applicability of the landscape approach.     

SSU rRNA reveals a sequential increase in shell complexity among the euglyphid testate amoebae (Rhizaria: Euglyphida)

The existing data on the molecular phylogeny of filose testate amoebae from order Euglyphida has revealed contradictions between traditional morphological classification and SSU rRNA phylogeny and, moreover, the position of several important genera remained unknown. We therefore carried out a study aiming to fill several important gaps and better understand the relationships among the main euglyphid testate amoebae and the evolutionary steps that led to the present diversity at a higher level. We obtained new SSU rRNA sequences from five genera and seven species. This new phylogeny obtained shows that (1) the clade formed by species of genera Assulina and Placocista branches unambiguously at the base of the subclade of Euglyphida comprising all members of the family Trinematidae and genus Euglypha, (2) family Trinematidae (Trachelocorythion, Trinema, and Corythion) branches as a sister group to genus Euglypha, (3) three newly sequenced Euglypha species (E. cf. ciliata, E. penardi, and E. compressa) form a new clade within the genus. Since our results show that Assulina and Placocista do not belong to the Euglyphidae (unless the Trinematidae are also included in this family), we propose the creation of a new family named Assulinidae. Consequently, we give a family status to the genera Euglypha and (tentatively) Scutiglypha, which become the new family Euglyphidae. The evolutionary pattern suggested by SSU rRNA phylogeny shows a clear tendency towards increasing morphological complexity of the shell characterised by changes in the symmetry (migration of the aperture to a ventral position and/or compression of the shell) and the appearance of specialised scales at the aperture (in families Trinematidae and Euglyphidae).     

Anatomical diversity and regressive evolution in trichomanoid filmy ferns (Hymenophyllaceae): a phylogenetic approach

To infer the anatomical evolution of the Hymenophyllaceae (filmy ferns) and to test previously suggested scenarios of regressive evolution, we performed an exhaustive investigation of stem anatomy in the most variable lineage of the family, the trichomanoids, using a representative sampling of 50 species. The evolution of qualitative and quantitative anatomical characters and possibly related growth-forms was analyzed using a maximum likelihood approach. Potential correlations between selected characters were then statistically tested using a phylogenetic comparative method. Our investigations support the anatomical homogeneity of this family at the generic and sub-generic levels. Reduced and sub-collateral/collateral steles likely derived from an ancestral massive protostele, and sub-collateral/collateral types appear to be related to stem thickness reduction and root apparatus regression. These results corroborate the hypothesis of regressive evolution in the lineage, in terms of morphology as well as anatomy. In addition, a heterogeneous cortex, which is derived in the lineage, appears to be related to a colonial strategy and likely to a climbing phenotype. The evolutionary hypotheses proposed in this study lay the ground for further evolutionary analyses that take into account trichomanoid habitats and accurate ecological preferences.     

Distinguishing microsite and competition processes in tree growth dynamics: an a priori spatial modeling approach

Spatially oriented studies have examined the role of competition on plant populations and communities but not the combined effects of microsite heterogeneity and competition. The aim of this study was threefold: first, to apply and test a common geostatistical tool (semivariograms) to disentangle competition and microsite effects; second, to assess the results of this methodology against a generalized early stand development model for tree populations; and third, to examine the role and timing of microsite and competition processes in early population stages. We mapped and measured annual relative growth rates of trees in three different-aged ponderosa pine stands in Patagonia, Chile. We tested the relative support of five a priori semivariogram-based hypotheses and showed that through stand development, many sites followed our expected sequence of semivariogram models. These translated to initial spatially random growth followed by microsite-dominated, mixed microsite and competition, and finally pure competition effects on growth. Our approach will have many and diverse applications wherever processes differ in the type of spatial pattern they exhibit as well as in spatial scale. We emphasize that this methodology works best when there is strong a priori support for the hypotheses being tested but the timing, strength, and occurrence of processes are not known.     

Strategies of zooplanktivory shape the dynamics and diversity of littoral plankton communities: a mesocosm approach

Planktivorous fish can exert strong top‐down control on zooplankton communities. By incorporating different feeding strategies, from selective particulate feeding to cruising filter feeding, fish species target distinct prey. In this study, we investigated the effects of two species with different feeding strategies, the three‐spined stickleback (Gasterosteus aculeatus (L.)) and roach (Rutilus rutilus (L.)), on a low‐diversity brackish water zooplankton community using a 16‐day mesocosm experiment. The experiment was conducted on a small‐bodied spring zooplankton community in high‐nutrient conditions, as well as a large‐bodied summer community in low‐nutrient conditions. Effects were highly dependent on the initial zooplankton community structure and hence seasonal variation. In a small‐bodied community with high predation pressure and no dispersal or migration, the selective particulate‐feeding stickleback depleted the zooplankton community and decreased its diversity more radically than the cruising filter‐feeding roach. Cladocerans rather than copepods were efficiently removed by predation, and their removal caused altered patterns in rotifer abundance. In a large‐bodied summer community with initial high taxonomic and functional diversity, predation pressure was lower and resource availability was high for omnivorous crustaceans preying on other zooplankton. In this community, predation maintained diversity, regardless of predator species. During both experimental periods, predation influenced the competitive relationship between the dominant calanoid copepods, and altered species composition and size structure of the zooplankton community. Changes also occurred to an extent at the level of nontarget prey, such as microzooplankton and rotifers, emphasizing the importance of subtle predation effects. We discuss our results in the context of the adaptive foraging mechanism and relate them to the natural littoral community.     

N-terminal tau truncation in the pathogenesis of Alzheimer's disease (AD): Developing a novel diagnostic and therapeutic approach

Tau truncation occurs at early stages during the development of human Alzheimer's disease (AD) and other tauopathy dementias. Tau cleavage, particularly in its N-terminal projection domain, is able to drive per se neurodegeneration, regardless of its pro-aggregative pathway(s) and in fragment(s)-dependent way. In this short review, we highlight the pathological relevance of the 20-22 kDa NH₂-truncated tau fragment which is endowed with potent neurotoxic “gain-of-function” action(s), both in vitro and in vivo. An extensive comment on its clinical value as novel progression/diagnostic biomarker and potential therapeutic target in the context of tau-mediated neurodegeneration is also provided.     

Cunaxidae (Acari: Prostigmata) diversity and population dynamics in garlic (Allium sativum) crop fields

Agroecosystems are altered systems whose soil structure has changed affecting the dynamics of soil organisms. This paper aims at evaluation of the effects of garlic farming practices on phenology, richness, abundance, composition and diversity of soil-dwelling Cunaxidae. Ten pilot plots in Guanajuato State were sampled from August 2002 to July 2005, every month, 8 months per year. Ten soil samples (1 kg) were taken from each plot and extracted in Berlese-Tullgren funnels. A total of 108 cunaxids were found, belonging to 11 species. Neocunaxoides andrei was the most abundant, and Cunaxa evansi and Armascirus sp. were least abundant. Relative abundance was highest after harvesting and during plant growth, and lowest during planting. Dactyloscirus nicobarensis and D. candylus were present from planting to harvesting. According to Sörensen’s similarity coefficient between cultivation stages, Cunaxidae communities were similar during plant growth and harvesting, sharing 80 % of the species. The highest abundance and diversity were found in 2004, during and after harvesting. Cunaxid species increased over 100 % from planting to the harvesting phase, suggesting that they play an important role in the soil agrosystems food web. Species composition and diversity in cunaxid communities present in garlic crop fields varied with agricultural phase, but little change was observed among the years studied. All species found in this study are new records for the state of Guanajuato and for the garlic crop fields.     

Assessment of bacterial endosymbiont diversity in Otiorhynchusspp. (Coleoptera: Curculionidae) larvae using a multitag 454 pyrosequencing approach

Background

Weevils of the genus Otiorhynchus are regarded as devastating pests in a wide variety of horticultural crops worldwide. So far, little is known on the presence of endosymbionts in Otiorhynchus spp.. Investigation of endosymbiosis in this genus may help to understand the evolution of different reproductive strategies in these weevils (parthenogenesis or sexual reproduction), host-symbiont interactions, and may provide a future basis for novel pest management strategy development. Here, we used a multitag 454 pyrosequencing approach to assess the bacterial endosymbiont diversity in larvae of four economically important Otiorhynchus species.

Results

High-throughput tag-encoded FLX amplicon pyrosequencing of a bacterial 16S rDNA fragment was used to characterise bacterial communities associated with different Otiorhynchus spp. larvae. By sequencing a total of ~48,000 PCR amplicons, we identified 49 different operational taxonomic units (OTUs) as bacterial endosymbionts in the four studied Otiorhynchus species. More than 90% of all sequence reads belonged either to the genus Rickettsia or showed homology to the phylogenetic group of “Candidatus Blochmannia” and to endosymbionts of the lice Pedicinus obtusus and P. badii. By using specific primers for the genera Rickettsia and “Candidatus Blochmannia”, we identified a new phylogenetic clade of Rickettsia as well as “Candidatus Nardonella” endosymbionts in Otiorhynchus spp. which are closely related to “Candidatus Blochmannia” bacteria.

Conclusions

Here, we used multitag 454 pyrosequencing for assessment of insect endosymbiotic communities in weevils. As 454 pyrosequencing generates only quite short sequences, results of such studies can be regarded as a first step towards identifying respective endosymbiotic species in insects. In the second step of our study, we analysed sequences of specific gene regions for a more detailed phylogeny of selected endosymbiont genera. As a result we identified the presence of Rickettsia and “Candidatus Nardonella” endosymbionts in Otiorhynchus spp.. This knowledge is an important step in exploring bacteria-insect associations for potential use in insect pest control.