Neurological phenotype and reduced lifespan in heterozygous Tim23 knockout mice, the first mouse model of defective mitochondrial import

The Tim23 protein is the key component of the mitochondrial import machinery. It locates to the inner mitochondrial membrane and its own import is dependent on the DDP1/TIM13 complex. Mutations in human DDP1 cause the Mohr-Tranebjaerg syndrome (MTS/DFN-1; OMIM #304700), which is one of the two known human diseases of the mitochondrial protein import machinery. We created a Tim23 knockout mouse from a gene trap embryonic stem cell clone. Homozygous Tim23 mice were not viable. Heterozygous F1 mutants showed a 50% reduction of Tim23 protein in Western blot, a neurological phenotype and a markedly reduced life span. Haploinsufficiency of the Tim23 mutation underlines the critical role of the mitochondrial import machinery for maintaining mitochondrial function.     

Lettuce for human consumption collected in Costa Rica contains complex communities of culturable oxytetracycline- and gentamicin-resistant bacteria

The present widespread use of antimicrobials in crop farming is based upon their successful application in human medicine. However, recent evidence suggests that the massive anthropogenic release of antimicrobials into the biosphere has selected for resistant bacteria and facilitated the transfer of resistance genes among them. This work deals with the examination of iceberg lettuce collected at 10 farms from two regions in Costa Rica. Farmers from nine sampling sites regularly apply commercial formulations containing gentamicin, oxytetracycline, streptomycin, or a combination of them without being able to indicate how often and how much of these products have been sprayed onto the crops. One organic farm was also investigated for comparative purposes. Oxytetracycline- and gentamicin-resistant bacteria were abundantly detected using selective enrichment cultures. Furthermore, colony mixtures from selective plates were characterized by chemotaxonomical and molecular fingerprinting methods. Both types of resistant communities accounted for a significant fraction of all culturable bacteria and included several resistance genes as well as factors for their potential horizontal transfer. Given the fact that lettuce is eaten raw, it may contribute to the dissemination of antimicrobial-resistant bacteria and/or their resistance genes from the environment to the microbial biota of the human intestine.     

Mineralisationsuntersuchungen in der Malcolmia cephallenica-und der cerastiumarabis verna-assoziation auf Kephallinia

Zusammenfassung Aus den vorliegenden Befunden geht hervor, daß in einem humusreichen Substrat die Mineralisation bodeneigenen Materials infolge des hier sehr regen Mikroorganismenlebens schneller erfolgt, als in Böden, die arm an organischer Substanz sind. Die Fruchtbarkeit eines Kohlenstoff-reichen Bodens zeigt sich innerhalb der Malcolmia cephallenica-Assoziation deutlich in der größeren Zahl von Pflanzenarten. Wird jedoch in einen humusreichen Boden organische Substanz inkubiert, so verlaufen die Mineralisationsvorgänge sehr viel langsamer als in humusarmen Substraten.

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Summary Soil samples from four places under two plant associations (Malcolmia cephallenica-and Cerastium-Arabis vernaass.) were taken on the Greek island of Kephallinia. The mineralisation of carbon, nitrogen and phosphorus was studied by laboratory measurements.The highest production of CO₂ was found in the soil with the highest amount of humus and nitrogen. In this soil was also the best mineralisation of nitrogen. The incubation of organic matter added to soil samples caused a high activity just in such soils which had the lowest amount of C and N. The decomposition and mineralisation of added pepton and lecithin was better in the poor than in the rich soils.

     

RAPD analysis of genetic variation between a group of rose cultivars and selected wild rose species

The genetic variability based on random-amplified polymorphic DNA markers was analysed among 10 cultivated rose varieties and 9 wild species from three different series of the genus Rosa. Using 13 different RAPD primers, 104 polymorphic DNA fragments with a high potential to differentiate rose genotypes could be produced. A dendrogram displaying the relative genetic similarities among the genotypes shows the existence of large genetic diversity among the cultivated roses as compared to the wild species. Furthermore, the main clusters found here are in agreement with known pedigrees and the classical taxonomy. However, the relationships between cultivated roses as inferred by RAPD markers do not correlate with the classical rose classification system. From the present data it is concluded that cultivated roses display a high level of genetic variability despite the fact that single morphological and physiological characters may be less polymorphic within rose groups. This contrasts with the widely accepted opinion of a lack of genetic variability in roses. This is also in accordance with the reported history of rose breeding which makes it highly probable that rose genomes comprise mosaics of different species genomes. As a consequence, it may be possible to utilize the high genetic variability of all genetic traits not under actual selection by breeders for future breeding programmes.     

Establishment and characterization of a betaxanthin-producing cell culture from Portulaca grandiflora

Cell cultures derived from three yellow flowering Portulaca grandiflora genotypes contained betacyanins rather than betaxanthins. A betaxanthin-producing cell culture was obtained by subculturing orange cell clusters isolated from the red-violet cell culture of a violet flowering P. grandiflora genotype. Selection of the most strongly yellow coloured cell material reduced the portion of betacyanins considerably and resulted in a P. grandiflora cell culture characterized by a high concentration of betaxanthins and the occurrence of free betalamic acid. Vulgaxanthin I was the main compound. Besides these pigments carotenoids and flavonoids were detectable.Betaxanthin biosynthesis strongly dependend on light. Product accumulation reached its maximum during the stationary phase of the growth cycle. Excretion of pigments, especially of betalains, could not be detected. Vulgaxanthin I as found in the cell culture was identical with one of two main betaxanthins in the yellow petals of P. grandiflora.The yellow P. grandiflora cells grew well on solid modified Murashige and Skoog medium but failed to grow in liquid medium after a few subcultures. In contrast, white P. grandiflora suspension cultures could be established repeatedly.Abbreviations A absorbance - BX I and BX II betaxanthin fractions - DOPA dihydroxyphenylalanin - DW cell dry weight - molar extinction coefficient - SS solvent system     

Closing the Commons: Cooperation for Gain or Restraint?

Research concerning the value of communal resource management is limited in two respects. First, while many studies present evidence that communal management is common among traditional societies, a strong theoretical basis is lacking to explain why individuals participate in monitoring and sanctioning efforts. Second, few studies have actually demonstrated resource conservation. There are several ecological and economic reasons for thinking that groups may find it harder to design appropriate conservation measures than to prevent free-riding. However, if groups can surmount these problems, communal management may have advantages over privatization or government control. These arguments are illustrated using results from a pilot study of the communal management of mother-of-pearl shell (Trochus niloticus) in the Kei Islands of Eastern Indonesia. It is found that villagers successfully cooperate to defend access to, and regulate their own harvest of trochus. In doing so, they are able to prevent free-riding, and to provide themselves with a long-term source of cash income. However, it is here argued that their aim is gain rather than restraint.     

Cell membrane is a more sensitive target than cytoplasm to dense ionization produced by auger electrons

To improve radioimmunotherapy with Auger electron emitters, we assessed whether the biological efficiency of (125)I varied according to its localization. A-431 and SK-OV-3 carcinoma cells were incubated with increasing activities (0-4 MBq/ml) of (125)I-labeled vectors targeting the cell membrane, the cytoplasm or the nucleus. We then measured cell survival by clonogenic assay and the mean radiation dose to the nucleus by assessing the cellular medical internal radiation dose (MIRD). The relationship between survival and the radiation dose delivered was investigated with a linear mixed regression model. For each cell line, we obtained dose-response curves for the three targets and the reference values (i.e., the dose leading to 75, 50 or 37% survival). When cell survival was expressed as a function of the total cumulative decays, nuclear (125)I disintegrations were more harmful than disintegrations in the cytoplasm or at the cell membrane. However, when survival was expressed as a function of the mean radiation dose to the nucleus, toxicity was significantly higher when (125)I was targeted to the cell membrane than to the cytoplasm. These findings indicate that the membrane is a more sensitive target than the cytoplasm for the dense ionization produced by Auger electrons. Moreover, cell membrane targeting is as cytotoxic as nuclear targeting in SK-OV-3 cells. We suggest that targeting the membrane rather than the cytoplasm may contribute to the development of more efficient radioimmunotherapies based on Auger electron radiation, also because most of the available vectors are directed against cell surface antigens.     

Potential of patulin production by Penicillium expansum strains on various fruits

In this study, we investigated the pathogenicity and patulin production by ten strains of Penicillium expansum on various fruits (apples, apricots, kiwis, plums and peaches) at two (4°C and 25°C) different temperature regimes. All strains caused the infectious rots on all fruits at 4 and 25°C except one strain (PEX 09) at 4°C. Two strains (PEX 20 and PEX 12) out of ten produced the highest amounts of patulin on all fruits tested. The patulin production by P. expansum is high at 25°C compared to 4°C. All strains of P. expansum accumulated patulin ranging from 100–13,200 μg/kg and nine strains ranging from 100–12,100 μg/kg in all fruits at 25°C and 4°C, respectively. Among ten strains of P. expansum, strain PEX 20 produced the greatest amount of patulin on apricots (13,200 μg/kg of rotten fruit) and on apples (12,500 μg/kg) at 25°C after 9 days of incubation. At 4°C, this strain produced 12,100, 12,000, 2,100 and 1,200 μg/kg of patulin on apricots, apples, plums and peaches, respectively, after 45 days of incubation. Strain PEX 12 produced the highest amount of patulin on kiwis (10,700 μg/kg) at 25°C and 10,300 μg/kg at 4°C. Patulin production by P. expansum on peaches and plums at both temperatures were lower than other fruits. The results of this study showed that careful removal of rotten fruits is essential to produce patulin-free fruit juice, since high patulin levels in apricots, apples and kiwis could result in a level greater than 50 μg/kg of this mycotoxin in finished fruit juices, when one contaminated fruit occurs in 264, 250 and 214 fruits, respectively. So, the fruit processors should take care in not using rotten fruits for juice production to avoid the patulin problem worldwide, since this study proved that most important fruits being used for juice production and direct human consumption are susceptible to P. expansum and subsequent patulin production even at low temperatures. This is the first comprehensive report regarding patulin production by different strains of P. expansum on various fruits from Italy at different temperature regimes.     

Effect of weight loss on lactate transporter expression in skeletal muscle of obese subjects.

The effects of weight loss on skeletal muscle lactate transporter [monocarboxylate transporter (MCT)] expression in obese subjects were investigated to better understand how lactate transporter metabolism is regulated in insulin-resistant states. Ten obese subjects underwent non-macronutrient-specific energy restriction for 15 wk. Anthropometric measurements and a needle biopsy of the vastus lateralis muscle before and after the weight loss program were performed. Enzymatic activity, fiber type distribution, and skeletal muscle MCT protein expression were measured. Muscle from nonobese control subjects was used for comparison of MCT levels. The program induced a weight loss of 9.2 +/- 1.6 kg. Compared with controls, muscle from obese subjects showed a strong tendency (P = 0.06) for elevated MCT4 expression (+69%) before the weight loss program. MCT4 expression decreased (-7%) following weight loss to reach levels that were not statistically different from control levels. There were no differences in MCT1 expression between controls and obese subjects before and after weight loss. A highly predictive regression model (R2 = 0.93), including waist circumference, citrate synthase activity, and percentage of type 1 fibers, was found to explain the highly variable MCT1 response to weight loss in the obese group. Therefore, in obesity, MCT1 expression appears linked both to changes in oxidative parameters and to changes in visceral adipose tissue content. The strong tendency for elevated expression of muscle MCT4 could reflect the need to release greater amounts of muscle lactate in the obese state, a situation that would be normalized with weight loss as indicated by decreased MCT4 levels.