Molecular Population Genetics and Evolution of the Chagas’ Disease Vector Triatoma infestans (Hemiptera: Reduviidae)

Triatoma infestans (Klug) is the main vector of Chagas’ disease in the Southern Cone of Latin America between the latitudes 10° S and 46° S. The long-term effectiveness of the control campaigns is greatly dependent upon the vector population structure. Mitochondrial DNA (mtDNA) genes have been used in a number of T. infestans population genetic analyses. However, the maternally inherited markers as well as nuclear ribosomal DNA analyzed until the present exhibited low or limited levels of variation. Analyses based on microsatellite markers strongly supported the existence of some type of stratification in T. infestans populations and supported the hypothesis of vector population recovery from survivors of the insecticide-treated areas, highlighting the value of population genetic analyses in assessing the effectiveness of Chagas’ disease vector control programmes. Although phylogeographic studies have generally suggested a Bolivian Andean origin of T. infestans, they recovered two reciprocal monophyletic groups of T. infestans and Bolivian populations who were not basal as expected for an ancestral group. In addition, a non-Andean origin could not be excluded by mtDNA genealogies that included sylvatic bugs from Gran Chaco. On the other side, mitochondrial and microsatellite markers supported the hypothesis of two independent migration events of colonization and secondary contacts in southern South America. Since the phylogenetic analyses remain inconclusive, more sequences, not only from mitochondrial genes but also from nuclear genes, need to be examined.     

The Role of Mutant RNA in the Pathogenesis of Huntington’s Disease and Other Polyglutamine Diseases

Molecular Biology - Polyglutamine diseases are rare, inherited neurodegenerative pathologies that arise as a result of expansion of trinucleotide CAG repeats in the coding segment of certain genes....     

The Rate of Human Germline Mutations—Variable Factor of Evolution and Diseases

Russian Journal of Genetics - The emergence of genetic diseases and evolutionary processes are associated with the flow of genetic information from one generation to another, in which genetic...     

Strategies for evaluating indicators based on guidelines from the Environmental Protection Agency’s Office of Research and Development

The Environmental Protection Agency’s Office of Research and Development (ORD) has prepared technical guidelines to evaluate the suitability of ecological indicators for monitoring programs. The guidelines were adopted by ORD to provide a consistent framework for indicator review, comparison and selection, and to provide direction for research on indicator development. The guidelines were organized within four evaluation phases: (1) conceptual relevance; (2) feasibility of implementation; (3) response variability; (4) interpretation and utility. Three example indicators were analyzed to illustrate the use of the guidelines in an evaluation. The examples included a direct chemical measurement (dissolved oxygen concentration), an estuarine benthic community index, and a stream fish community index of biotic integrity. Comparison of the three examples revealed differences in approach, style and types of information used to address each guideline. The Evaluation Guidelines were intended to be flexible within a consistent framework and the various strategies used in the examples demonstrate that the process can be useful for a wide variety of indicators and program objectives.     

The Role of Inflammatory and Oxidative Stress Mechanisms in the Pathogenesis of Parkinson’s Disease: Focus on Astrocytes

Neuroinflammation plays a key role in the pathogenesis of Parkinson’s disease (PD). Epidemiologic, animal, human, and therapeutic studies support the role of oxidative stress and inflammatory cascade in initiation and progression of PD. In Parkinson’s disease pathophysiology, activated glia affects neuronal injury and death through production of neurotoxic factors like glutamate, S100B, tumor necrosis factor alpha (TNF-α), prostaglandins, and reactive oxygen and nitrogen species. As disease progresses, inflammatory secretions engage neighboring cells, including astrocytes and endothelial cells, resulting in a vicious cycle of autocrine and paracrine amplification of inflammation leading to neurodegeneration. The exact mechanism of these inflammatory mediators in the disease progression is still poorly understood. In this review, we highlight and discuss the mechanisms of oxidative stress and inflammatory mediators by which they contribute to the disease progression. Particularly, we focus on the altered role of astroglial cells that presumably initiate and execute dopaminergic neurodegeneration in PD. In conclusion, we focus on the molecular mechanism of neurodegeneration, which contributes to the basic understanding of the role of neuroinflammation in PD pathophysiology.     

Apes and Tricksters: The Evolution and Diversification of Humans’ Closest Relatives

The evolutionary history of humans comprises an important but small branch on the larger tree of ape evolution. Today’s hominoids—gibbons, orangutans, gorillas, chimpanzees, and humans—are a meager representation of the ape diversity that characterized the Old World from 23–5 million years ago. In this paper, I briefly review this evolutionary history focusing on features important for understanding modern ape and human origins. As the full complexity of ape evolution is beyond this review, I characterize major geographic, temporal, and phylogenetic groups using a few flagship taxa. Improving our knowledge of hominoid evolution both complicates and clarifies studies of human origins. On one hand, features thought to be unique to the human lineage find parallels in some fossil ape species, reducing their usefulness for identifying fossil humans. On the other hand, the Miocene record of fossil apes provides an important source for generating hypotheses about the ancestral human condition; this is particularly true given the dearth of fossils representing our closest living relatives: chimpanzees and gorillas.     

The Influence of Farmers’ Strategies on Local Practices,Knowledge, and Varietal Diversity of the Safou Tree (Dacryodes edulis) in Western Cameroon

Economic Botany - Highly valued for its edible fruits, the safou tree, Dacryodes edulis, is a major component of farming systems in Central Africa. In Cameroon, the species has drawn much attention...     

The ‘Unicorn’ Dinosaur That Wasn’t: A New Reconstruction of the Crest of Tsintaosaurus and the Early Evolution of the Lambeosaurine Crest and Rostrum

The lambeosaurine Tsintaosaurus spinorhinus has traditionally been reconstructed with an elevated, hollow, spike-like crest composed entirely of the nasal bones, although this has been disputed. Here, we provide a new reconstruction of the skull of this species based on reexamination and reinterpretation of the morphology and articular relationships of the type and Paratype skulls and a fragmentary crest. We confirm the presence of a supracranial crest composed of the elevated nasal bones, but also including the premaxillae. We hypothesize that the crest is a tall, lobate, hollow structure that projects dorsally and slightly caudally a distance greater than the height of the skull along the quadrate. In our reconstruction, the nasal passage passes through the crest, but enters the skull rostral to the tubular process of the nasals, not through it. Tsintaosaurus spinorhinus is rediagnosed on the basis of a suite of cranial autapomorphies including a circumnarial fossa subdivided into three accessory fossae, prefrontal with ascending rostral process and lateral flange, nasals fused sagittally to form elongate tubular process that rises dorsally from skull roof, each nasal being expanded rostrocaudally into a rhomboid distal process, and medial processes of premaxillae at the summit of the cranial crest inserted between rhomboid processes of nasals. Tsintaosaurus spinorhinus lacks characters that are present in more derived lambeosaurines (parasaurolophins and lambeosaurins), such as rotation of the caudal margin of the crest to an acute angle with the skull roof, lateral processes of the nasals that enclose part of the intracranial cavity and participate in the formation of the walls of the common median chamber, and a smooth narial fossa lacking ridges and accessory fossae. We hypothesize that ancestrally the rostrum of lambeosaurines may have been more similar to that in Saurolophinae, and became subsequently reduced in complexity during evolution of the group.     

Environmental Influence on Planktonic Cladocerans and Copepods in the Floodplain of the Upper River Paraná, Brazil

The abundance of microcrustacean species recorded in plankton samples from the littoral and pelagic zones of the Upper Paran River, State of Mato Grosso do Sul, Brazil, was evaluated in relation to abiotic and biotic environmental factors. The cladocerans Bosminopsis deitersi and Bosmina hagmann i were most abundant. The presence or absence of aquatic macrophytes also influenced abundance and species composition. The true zooplankton species were most abundant at the pelagic stations, while species of Chydoridae and Macrothricidae contributed markedly to microcrustacean abundance and species richness at littoral stations. Species abundance was also strongly affected by water level variation. Microcrustaceans, mainly bosminids, were most abundant during low water. During high water, bosminids decreased in abundance while most other species increased. The higher variation of the environmental factors during high water probably explains the shift in abundance patterns. Changes in water level increased mixing of littoral and pelagic microcrustaceans between sampling stations.     

Multi-target Design Strategies in the Context of Alzheimer’s Disease: Acetylcholinesterase Inhibition and NMDA Receptor Antagonism as the Driving Forces

In recent years, the multi-target-directed ligand concept has been used to design a variety of molecules hitting different biological targets for Alzheimer’s disease. We have sought to combine, in the same molecule, the neuroprotective action of N-methyl-d-aspartate receptor antagonism with the symptomatic relief offered by cholinergic activity through acetylcholinesterase inhibition. This strategy could potentially maintain the positive outcomes of memantine–acetylcholinesterase inhibitor combinations, but with the benefits of a single molecule therapy. Herein, we discuss selected examples of multifunctional compounds, which we rationally designed to simultaneously modulate these targets. We also examine the intertwined relationship between acetylcholinesterase, N-methyl-d-aspartate receptors, and other active players in the neurotoxic cascade.     

Environmental Occurrence of the Whipple’s Disease Bacterium (Tropheryma whippelii)

Whipple’s disease is a systemic disorder in which a gram-positive rod-shaped bacterium is constantly present in infected tissues. After numerous unsuccessful attempts to culture this bacterium, it was eventually characterized by 16S rRNA gene analysis to be a member of the actinomycetes. The name Tropheryma whippelii was proposed. Until now, the bacterium has only been found in infected human tissues, but there is no evidence for human-to-human transmission. Here we report the detection of DNA specific for the Whipple’s disease bacterium in 25 of 38 wastewater samples from five different sewage treatment plants in the area of Heidelberg, Germany. These findings provide the first evidence that T. whippelii occurs in the environment, within a polymicrobial community. This is in accordance with the phylogenetic relationship of this bacterium as well as with known epidemiological aspects of Whipple’s disease. Our data argue for an environmental source for infection with the Whipple’s disease bacterium.Whipple’s disease, which was first described in 1907 as intestinal lipodystrophy (18), is a multisystem disorder characterized by the presence of gram-positive, rod-shaped bacteria in infected human tissues (2). Numerous attempts to culture the bacterium associated with Whipple’s disease have failed (2), and eventually its phylogenetic position within the actinomycetes was established by 16S rRNA gene analysis (11, 19). The name Tropheryma whippelii was proposed (11).The clinical presentation of Whipple’s disease is heterogeneous. Frequently, patients suffer for years from arthralgias, chronic diarrhea, and weight loss, and less often from dementia or cardiac insufficiency. If untreated, the disease is usually fatal, but with appropriate antibiotic therapy the prognosis is favorable (2). However, the pathogenesis of Whipple’s disease appears to involve more than just an infection with T. whippelii. Immunological abnormalities are presumed to play a necessary role as predisposing factors (2, 7, 8), a view which is strengthened by the detection of T. whippelii in association with AIDS (5).Two outstanding questions in the epidemiology of Whipple’s disease are the bacterium’s natural habitat and the route of infection. Until now, T. whippelii has never been found outside of infected human hosts, and although an oral route of infection has often been suspected (10), it has not been proven. There is no evidence for human-to-human transmission.A reassessment of its phylogeny revealed a close relationship of the Whipple’s disease bacterium to typical environmental bacteria, such as the cellulomonads and the rare group B peptidoglycan organisms (6). This would support the hypothesis that T. whippelii may be a soil or water inhabitant. This may also explain the difficulties involved with its culture, as an estimated 80 to 99% of bacteria occurring in such natural environments are not culturable on artificial media (14, 17) and uncultured members of the actinomycete line of descent have been found in different environments and geographical locations (12). Soil and water bacteria tend to concentrate in sewage to form communities in which a large variety of different species are found. Therefore, the search for the Whipple’s disease bacterium was concentrated at sewage treatment plants.From September 1995 to July 1996, a total of 38 effluent samples from the sedimentation ponds of five different sewage treatment plants were examined by PCR for the presence of the Whipple’s disease bacterium. The sewage treatment plants are located within a distance of 5 to 25 km from Heidelberg, Germany (Fig. ​(Fig.1).1). Effluent was sampled in 1,000-ml single-use plastic flasks and filtered as described previously (4) in portions of 25 ml through cellulose acetate prefilters (25-mm diameter, 5-μm pore size; Sartorius, Göttingen, Germany). It was then passed through polyvinylidene fluoride filters (25-mm diameter, 0.45-μm pore size; Millipore, Bedford, Mass.). The DNA from the 0.45-μm-pore-size filters was extracted with the EnviroAmp Legionella sample preparation kit (Perkin-Elmer, Norwalk, Conn.), with the addition of 0.2% bovine serum albumin to the water in the final extraction step. Distilled water for negative controls was sampled in the same flasks and treated in the same way as the sewage. Open in a separate windowFIG. 1Map of the area around Heidelberg, Germany, displaying the rivers Rhine (Rhein) and Neckar, the relevant townships (shaded areas with names in capital letters), and the five sewage treatment plants (dots) from which samples were taken. The inset in the figure shows the localization of the area within Germany.PCR amplification and detection were performed as described in detail elsewhere (15). Primers whip1 (5′-AGAGATACGCCCCCCGCAA) and whip2 (5′-ATTCGCTCCACCTTGCGA), which amplify a fragment of 267 bp from the 16S rRNA gene of the bacterium, were used. In addition to hybridization with oligonucleotide whip3 (5′-TGGTACAGAGGGTTGCAATA), a second hybridization in a separate reaction was performed with oligonucleotide whip4 (5′-GTAATGGCGGGGACTCACAG). The specificities of primers whip1 and whip2 and of probe whip3 have been tested previously (15), and testing of probe whip4 with the same set of 37 control bacteria gave the same results as those reported for whip3 (15).Of the 38 sewage samples tested, 25 were found to be positive by PCR and hybridization with both oligonucleotides (Table ​(Table1).1). Positive samples were found at each of the five sewage treatment plants. Most of the positive PCR products displayed relatively weak bands at the expected size of 267 bp. They also contained some extraneous bands, which were not of the expected size, probably due to the large amount of DNA from other organisms present in sewage. On hybridization, however, the PCR products displayed distinct bands, which were consistent between the two oligonucleotides (Fig. ​(Fig.2).2).

TABLE 1

Results of PCR for the Whipple’s disease bacterium from sewage samples