Population biology ofHortaea werneckii based on restriction patterns of mitochondrial DNA

Fifteen isolates ofHortaea werneckii, causative agent of tinea nigra in man, were examined with respect to restriction fragment length polymorphisms of mitochondrial DNA. Seven types of mtDNA, interpreted as populations, could be distinguished, with similarities between the restriction patterns ranging from 32 to 79%. Much of the variance originated from length mutations. Of the seven populations four represented isolates from man, two of which also comprised isolates from other sources. This makes adaptation ofH. werneckii towards association with man in its evolution unlikely; similarity in the chemical and/or physical characteristics of the different isolation sources, viz. salinity, seems more probable. mtDNA types were not correlated with geographic origin. Isolates with the same mtDNA type are widely geographically distributed.     

Common Mechanisms Underlying α-Synuclein-Induced Mitochondrial Dysfunction in Parkinson’s Disease

Parkinson’s disease (PD) is the most common neurological movement disorder characterized by the selective and irreversible loss of dopaminergic neurons in substantia nigra pars compacta resulting in dopamine deficiency in the striatum. While most cases are sporadic or environmental, about 10% of patients have a positive family history with a genetic cause. The misfolding and aggregation of α-synuclein (α-syn) as a casual factor in the pathogenesis of PD has been supported by a great deal of literature. Extensive studies of mechanisms underpinning degeneration of the dopaminergic neurons induced by α-syn dysfunction suggest a complex process that involves multiple pathways, including mitochondrial dysfunction and increased oxidative stress, impaired calcium homeostasis through membrane permeabilization, synaptic dysfunction, impairment of quality control systems, disruption of microtubule dynamics and axonal transport, endoplasmic reticulum/Golgi dysfunction, nucleus malfunction, and microglia activation leading to neuroinflammation. Among them mitochondrial dysfunction has been considered as the most primary target of α-syn-induced toxicity, leading to neuronal cell death in both sporadic and familial forms of PD. Despite reviewing many aspects of PD pathogenesis related to mitochondrial dysfunction, a systemic study on how α-syn malfunction/aggregation damages mitochondrial functionality and leads to neurodegeneration is missing in the literature. In this review, we give a detailed molecular overview of the proposed mechanisms by which α-syn, directly or indirectly, contributes to mitochondrial dysfunction. This may provide valuable insights for development of new therapeutic approaches in relation to PD. Antioxidant-based therapy as a potential strategy to protect mitochondria against oxidative damage, its challenges, and recent developments in the field are discussed.     

Structure of two macrolepidopteran assemblages on Salix nigra (Marsh) and Acer negundo L.: abundance,diversity, richness,and persistence of scarce species

1. Most insect species occur at low abundance but a greater research effort has been devoted to so‐called outbreak species and little research is available on scarce (low abundance) species that are typical of most insect species. 2. Larval free‐feeding macrolepidoptera of two riparian trees Salix nigra (Marsh) (black willow) and Acer negundo L. (box elder) were sampled and sorted by species and abundance. 3. Data collected established that the majority of species in the assemblages in each tree species occurred at low abundance in each of the 5 years when larvae were sampled. 4. Species in the Noctuidae and Geometridae dominated both assemblages. 5. On both trees, assemblages were dominated numerically by relatively few species, a pattern that has been observed for insect assemblages on plants in managed and unmanaged habitats.     

Temporal and spatial expression of mRNAs encoding pathogenesis-related proteins during ethylene-promoted leaflet abscission in Sambucus nigra*

Differential screening of a cDNA library generated from RNA extracted from ethylene-treated leaflet abscission zones of Sambucus nigra resulted in the isolation of 20 abscission-related clones. These clones could be grouped into seven families. Sequencing of members of these families revealed that the majority encoded pathogenesis-related (PR) proteins, and these could be identified by sequence homology as a polyphenol oxidase (PPO), a PR-1 type protein, a Chial type chitinase, a PR-4 type protein similar to the potato win peptides, a PR-6 type proteinase inhibitor, a Chia4 type chitinase and a metallothionein-like protein (Coupe, Taylor & Roberts 1995, Planta 197, 442–447). Northern analysis revealed that these mRNAs were not expressed in freshly excised material but accumulated primarily in the abscission zone tissue after 18 h of exposure to ethylene at a time when abscission of the leaflet explants had reached 70%. Expression of the PPO and the Chia4-type chitinase was ethylene-dependent while that of the PR-4 type was up-regulated in the abscission zone tissue in the absence of the gas. The characterization of these mRNAs and their encoded proteins is presented and their possible roles during abscission are discussed.