Impaired carotenogenesis can affect organization and functionality of etioplast membranes

The effects of impaired carotenogenesis on plastid membrane organization, functionality and stability were studied in etiolated barley plants grown at 20 and 30°C. The plants were treated with norflurazon or amitrole, two herbicides affecting phytoene desaturation and lycopene cyclization, respectively. At 20°C, the amitrole-treated etioplasts, which accumulated lycopene in their inner membranes, exhibited disorganized prolamellar bodies, containing a prevalent form of non-phototransformable protochlorophyllide (Pchlide). They also showed a certain difficulty in reducing the phototransformable pigment to chlorophyllide when exposed to light, and were unable to reform the active ternary complex [protochlorophyllide–oxidoreductase (POR)–Pchlide–NADPH] when placed back in darkness. No ultrastructural alterations were found in norflurazon-treated etioplasts, with carotenogenesis inhibited at the phytoene desaturation step. In these latter organelles, Pchlide, whose forms were comparable with those of the control etioplasts, was photoreduced quickly after illumination and the ternary complex was reformed during a subsequent dark period. Thus, the impaired carotenogenesis leading to the accumulation of lycopene showed greater interference with the etioplast membrane arrangement and functionality than did the earlier interruption of the biosynthetic pathway at the phytoene level. This might be due to the different interactions of the distinct carotenoid precursors with other membrane components. However, in etioplasts of norflurazon-treated plants, a rise in growth temperature caused a partial demolition of prolamellar bodies, showing a lowered thermostability of the carotenoid-deficient membranes. This latter effect strengthens the concept that a correct and complete carotenogenesis pathway, leading to the synthesis of polar carotenoids (i.e. xanthophylls), is required for the maintenance of stable plastid membranes.     

Response of bacterial community during bioremediation of an oil-polluted soil

AIM: To study the response of the bacterial community to bioremediation of a soil with an aged contamination of crude oil. METHODS AND RESULTS: The bacterial community in laboratory soil columns during a 72-day biostimulation treatment was followed by analysing the number of total cultivable hydrocarbon-degrading bacteria, soil respiratory activity and the 16S-23S rDNA internal transcribed spacer homoduplex heteroduplex polymorphisms (ITS-HHP) of total soil bacterial DNA. ITS-HHP permits an estimate of both length and sequence polymorphism in a 16S-23S rDNA spacer population, using to advantage the homoduplex and heteroduplex fragments that are generated during PCR. The treatment, made by air sparging and biostimulation with a mineral nutrient and surfactant solution, resulted in a 39.5% decrease of the total hydrocarbon content. Within 4 days of treatment onset the bacterial community underwent a first phase of activation that led to a substantial increase in the observable diversity. Subsequently, after a 12-day period of stability, another activation phase was observed with further shifts of the community structure and an increase in the abundance and diversity of catechol-2,3-dioxygenase (C23O) genes. CONCLUSIONS: The overall data suggest an important contribution of uncultivable bacteria to the soil bioremediation, since, during the second activation phase, the increases of the respiratory activity, bacterial diversity and C23O gene abundance and diversity were not accompanied by a corresponding increase of the cultivable bacteria number. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows that successive phases of activation of bacterial populations occur during a bioremediation treatment of oil-polluted soil.     

Ragweed presence in Trieste: clinical and aerobiological data

Summary Studies on ragweed have been carried out in the province of Trieste (Northern Italy) in which it is becoming widespread. The floristic records, the increasing amount of airborne pollen monitored and the relevant skin reactivity are reported. This phenomenon, though still at the beginning, is actually showing an upward trend due to man's intervention over wider and wider areas which as a consequence become suitable for the settlement of these anthropophitic species. The aerobiological data are compared to the skin reactivities of allergic subjects.     

Mitochondrial non-syndromic sensorineural hearing loss: a clinical, audiological and pathological study from Italy, and revision of the literature

Over the last decade, a number of distinct mutations in the mtDNA (mitochondrial DNA) have been found to be associated with both syndromic and non-syndromic forms of hearing impairment. Their real incidence as a cause of deafness is poorly understood and generally underestimated. Among the known mtDNA mutations, the A1555G mutation in the 12S gene has been identified to be one of the most common genetic cause of deafness, and it has been described to be both associated to non-syndromic progressive SNHL (sensorineural hearing loss) and to aminoglycoside-induced SNHL. In the present study, we have investigated the presence of mtDNA alterations in patients affected by idiopathic non-syndromic SNHL, both familiar and sporadic, in order to evaluate the frequency of mtDNA alterations as a cause of deafness and to describe the audiological manifestations of mitochondrial non-syndromic SNHL. In agreement with previous studies, we found the A1555G mutation to be responsible for a relevant percentage (5.4%) of cases affected with isolated idiopathic sensorineural hearing impairment.     

ENDOPHYTIC BACTERIA FROM SEEDS OF NICOTIANA TABACUM CAN REDUCE CADMIUM PHYTOTOXICITY

Although endophytic bacteria seem to have a close association with their host plant, little is known about the influence of seed endophytic bacteria on initial plant development and on their interactions with plants under conditions of metal toxicity. In order to further elucidate this close relationship, we isolated endophytic bacteria from surface sterilized Nicotiana tabacum seeds that were collected from plants cultivated on a cadmium-(Cd) and zinc-enriched soil. Many of the isolated strains showed Cd tolerance. Sterilely grown tobacco plants were inoculated with either the endogenous microbial consortium, composed of cultivable and noncultivable strains; single strains; or defined consortia of the most representative cultivable strains. Subsequently, the effects of inoculation of endophytic bacteria on plant development and on metal and nutrient uptake were explored under conditions with and without exposure to Cd. In general, seed endophytes were found to have a positive effect on plant growth, as was illustrated by an increase in biomass production under conditions without Cd. In several cases, inoculation with endophytes resulted in improved biomass production under conditions of Cd stress, as well as in a higher plant Cd concentration and total plant Cd content compared to noninoculated plants. These results demonstrate the beneficial effects of seed endophytes on metal toxicity and accumulation, and suggest practical applications using inoculated seeds as a vector for plant beneficial bacteria.     

Uniparental Genetic Heritage of Belarusians: Encounter of Rare Middle Eastern Matrilineages with a Central European Mitochondrial DNA Pool

Ethnic Belarusians make up more than 80% of the nine and half million people inhabiting the Republic of Belarus. Belarusians together with Ukrainians and Russians represent the East Slavic linguistic group, largest both in numbers and territory, inhabiting East Europe alongside Baltic-, Finno-Permic- and Turkic-speaking people. Till date, only a limited number of low resolution genetic studies have been performed on this population. Therefore, with the phylogeographic analysis of 565 Y-chromosomes and 267 mitochondrial DNAs from six well covered geographic sub-regions of Belarus we strove to complement the existing genetic profile of eastern Europeans. Our results reveal that around 80% of the paternal Belarusian gene pool is composed of R1a, I2a and N1c Y-chromosome haplogroups – a profile which is very similar to the two other eastern European populations – Ukrainians and Russians. The maternal Belarusian gene pool encompasses a full range of West Eurasian haplogroups and agrees well with the genetic structure of central-east European populations. Our data attest that latitudinal gradients characterize the variation of the uniparentally transmitted gene pools of modern Belarusians. In particular, the Y-chromosome reflects movements of people in central-east Europe, starting probably as early as the beginning of the Holocene. Furthermore, the matrilineal legacy of Belarusians retains two rare mitochondrial DNA haplogroups, N1a3 and N3, whose phylogeographies were explored in detail after de novo sequencing of 20 and 13 complete mitogenomes, respectively, from all over Eurasia. Our phylogeographic analyses reveal that two mitochondrial DNA lineages, N3 and N1a3, both of Middle Eastern origin, might mark distinct events of matrilineal gene flow to Europe: during the mid-Holocene period and around the Pleistocene-Holocene transition, respectively.     

Identification of amino acid residues critical for the B cell growth-promoting activity of HIV-1 matrix protein p17 variants

Background

HIV-1 matrix protein p17 variants (vp17s) detected in HIV-1-infected patients with non-Hodgkin's lymphoma (HIV-NHL) display, differently from the wild-type protein (refp17), B cell growth-promoting activity. Biophysical analysis revealed that vp17s are destabilized as compared to refp17, motivating us to explore structure-function relationships.

Phenological and aerobiological monitoring of allergenic flora in padua (Italy). Preliminary data

A phenological study on allergenic plants was carried out in Padua during 1995 in order to identify spontaneous and cultivated allergenic species in an urban area and their distribution, and to evaluate the relationship between anthesis length and airborne pollen concentrations. In some cases, there was no temporal overlap between phenological and aerobiological data, in particular forCorylaceae, Betulaceae, Chenopodiaceae, Amaranthaceae, Polygonaceae and Fagaceae.     

Belowground community responses to fire: meta‐analysis reveals contrasting responses of soil microorganisms and mesofauna

Global fire regimes are shifting due to climate and land use changes. Understanding the responses of belowground communities to fire is key to predicting changes in the ecosystem processes they regulate. We conducted a comprehensive meta‐analysis of 1634 observations from 131 empirical studies to investigate the effect of fire on soil microorganisms and mesofauna. Fire had a strong negative effect on soil biota biomass, abundance, richness, evenness, and diversity. Fire reduced microorganism biomass and abundance by up to 96%. Bacteria were more resistant to fire than fungi. Fire reduced nematode abundance by 88% but had no significant effect on soil arthropods. Fire reduced richness, evenness and diversity of soil microorganisms and mesofauna by up to 99%. We found little evidence of temporal trends towards recovery within 10 years post‐disturbance suggesting little resilience of the soil community to fire. Interactions between biome, fire type, and depth explained few of these negative trends. Future research at the intersection of fire ecology and soil biology should aim to integrate soil community structure with the ecosystem processes they mediate under changing global fire regimes.