Architecture of succinate dehydrogenase and reactive oxygen species generation

The structure of Escherichia coli succinate dehydrogenase (SQR), analogous to the mitochondrial respiratory complex II, has been determined, revealing the electron transport pathway from the electron donor, succinate, to the terminal electron acceptor, ubiquinone. It was found that the SQR redox centers are arranged in a manner that aids the prevention of reactive oxygen species (ROS) formation at the flavin adenine dinucleotide. This is likely to be the main reason SQR is expressed during aerobic respiration rather than the related enzyme fumarate reductase, which produces high levels of ROS. Furthermore, symptoms of genetic disorders associated with mitochondrial SQR mutations may be a result of ROS formation resulting from impaired electron transport in the enzyme.     

Excavation of a chimpanzee stone tool site in the African rainforest

Chimpanzees from the Tai forest of C?te d'Ivoire produce unintentional flaked stone assemblages at nut-cracking sites, leaving behind a record of tool use and plant consumption that is recoverable with archaeological methods. About 40 kilograms of nutshell and 4 kilograms of stone were excavated at the Panda 100 site. The data unearthed show that chimpanzees transported stones from outcrops and soils to focal points, where they used them as hammers to process foodstuff. The repeated use of activity areas led to refuse accumulation and site formation. The implications of these data for the interpretation of the earliest hominin archaeological record are explored.     

Dynamics of mammalian chromosome evolution inferred from multispecies comparative maps

The genome organizations of eight phylogenetically distinct species from five mammalian orders were compared in order to address fundamental questions relating to mammalian chromosomal evolution. Rates of chromosome evolution within mammalian orders were found to increase since the Cretaceous-Tertiary boundary. Nearly 20% of chromosome breakpoint regions were reused during mammalian evolution; these reuse sites are also enriched for centromeres. Analysis of gene content in and around evolutionary breakpoint regions revealed increased gene density relative to the genome-wide average. We found that segmental duplications populate the majority of primate-specific breakpoints and often flank inverted chromosome segments, implicating their role in chromosomal rearrangement.     

Intracranial meningioma causing partial amaurosis in a cat

Objective To describe a case of intracranial meningioma causing visual impairment in a cat, successfully treated by surgery. Procedures An adult neutered male domestic cat was referred with a 10‐month history of progressive visual impairment and altered behavior. Investigations included physical, ophthalmologic and neurological examinations as well as hematology, serum biochemistry and CT scan of the head. Results The menace response was absent in the left eye and decreased in the right eye. Electroretinograms were normal on both eyes, as was ophthalmic examination, ruling out an ocular cause and allowing a presumptive diagnosis of partial amaurosis due to a post‐retinal lesion. CT scan demonstrated a large sessile extra axial mass along the right parietal bone and thickening of the adjacent bone. Cerebrospinal fluid was not collected because high intracranial pressure represented a risk for brain herniation. A right rostrotentorial craniectomy was performed to remove the tumor. Ten days after surgery, vision was improved, neurological examination was normal and normal behavior was restored. Ten months after surgery, ophthalmological examination showed no visual deficit and CT scan did not reveal any sign of recurrence. Conclusion Advanced imaging techniques allow veterinarians to detect early cerebral diseases and to provide specific treatment when it is possible. In cases of feline amaurosis due to intracranial meningioma, the vital prognosis is good while the visual prognosis is more uncertain, but recovery of normal vision and normal behavior is possible as demonstrated in the present case.     

Compared effects of long-term pig slurry applications and mineral fertilization on soil denitrification and its end products (N2O, N2)

The long-term (9 years) effect of pig slurry applications vs mineral fertilization on denitrifying activity, N₂O production and soil organic carbon (C) (extractable C, microbial biomass C and total organic C) was compared at three soil depths of adjacent plots. The denitrifying activities were measured on undisturbed soil cores and on sieved soil samples with acetylene method to estimate denitrification rates under field or potential conditions. Pig slurry applications had a moderate impact on the C pools. Total organic C was increased by +6.5% and microbial biomass C by ≥25%. The potential denitrifying activity on soil suspension was stimulated (×1.8, P<0.05) 12 days after the last slurry application. This stimulation was still apparent, but not significant, 10 months later and, according to both methods of denitrifying activity measurement (r ²=0.916, P<0.01 on sieved soil; r ²=0.845, P<0.001 on soil cores), was associated with an increase in microbial biomass C above a threshold of about 105 mg kg⁻¹. The effect of pig slurry on denitrification and N₂O reduction rates was detected on the surface layer (0–20 cm) only. However, no pig slurry effect could be detected on soil cores at field conditions or after NO₃ ⁻ enrichments at 20°C. Although the potential denitrifying activity in sieved soil samples was stimulated, the N₂O production was lower (P<0.03) in the plot fertilized with pig slurry, indicating a lower N₂O/(N₂O + N₂) ratio of the released gases. The pig-slurry-fertilized plot also showed a higher N₂O reduction activity, which is coherent with the lower N₂O production in anaerobiosis.     

Additions of maize root mucilage to soil changed the structure of the bacterial community

The organic compounds released from roots (rhizodeposits) stimulate the growth of the rhizosphere microbial community. They may be responsible for the differences in the structure of the microbial communities commonly observed between the rhizosphere and the bulk soil. Rhizodeposits consists of a broad range of compounds including root mucilage. The aim of this study was to investigate if additions of maize root mucilage, at a rate of 70 μg C g⁻¹ day⁻¹ for 15 days, to an agricultural soil could affect the structure of the bacterial community. Mucilage additions moderately increased microbial C (+23% increase relative to control), which suggests that the turnover rate of microorganisms consuming this substrate was high. Consistent with this, the number of cultivable bacteria was enhanced by +450%. Catabolic (Biolog^® GN2) and 16S-23S intergenic spacer fingerprints exhibited significant differences between control and mucilage treatments. These data indicate that mucilage can affect both the metabolic and genetic structure of the bacterial community as shown by a greater catabolic potential for carbohydrates. We concluded that mucilage is likely to significantly contribute to differences in the structure of the bacterial communities present in the rhizosphere compared to the bulk soil.     

Alarming houbara bustard population trends in Asia

Relative abundance and density estimates of Asian houbara were assessed during the breeding season in two breeding grounds of migrant populations (China and south Kazakhstan) and in one breeding ground of a resident population (Oman), between 1998 and 2002. For the study period, the relative abundance was from 0.004 to 0.06 individual per km driven and density estimates varied from 0.01 to 0.2 houbara per km². Relative abundance and density of houbara declined by 63% and 69%, respectively in China, by 60% and 49%, respectively in Kazakhstan and by 50% and 75%, respectively in Oman. Overall, an average of 27-30% annual decline in both relative abundance and density was observed for the three regions. Despite being legally a strictly protected species in China, Kazakhstan and Oman, houbara are heavily hunted and poached on all their migration routes and wintering grounds. The current levels of hunting and poaching are not sustainable and without the immediate agreement and implementation of international conservation measures, the Asian houbara may face extinction in the wild in the foreseeable future.     

Changes in physicochemical characteristics and volatile constituents of strawberry (Cv. Cigaline) during maturation

Changes in the volatile composition of strawberries (cv. Cigaline) at six stages of maturity, from 28 to 44 days after anthesis, were investigated over two harvesting seasons. Volatiles were isolated by direct solvent extraction and analyzed by means of GC-FID and GC-MS, with special attention to the quantification of furanones. Firmness, skin color, soluble solids (SS), titratable acidity (TA), SS/TA ratio, organic acids, and sugars were also determined. With increasing maturity, soluble solids, SS/TA ratio, Minolta a value, and levels of sucrose, glucose, fructose, and malic acid increased, whereas Minolta L value, hue angle (), titratable acidity, and levels of citric acid decreased. Furanones and esters were generally not detected before half-red fruits, whereas C(6) compounds were the main compounds in immature fruits. During maturation, levels of these so-called green components decreased drastically, whereas levels of key flavor compounds increased significantly and were closely correlated with skin color development. Maximum volatile production was observed in fully red fruits.     

Evidence for the involvement of arabinoxylan and xylanases in refrigerated dough syruping

The relationship between syruping in refrigerated doughs upon prolonged storage and different aspects of arabinoxylan (AX) hydrolysis was investigated using Triticum aestivum xylanase inhibitor (TAXI) and different xylanases in the dough formula. Dough characteristics were evaluated with strong emphasis on the AX population and its fate as a function of storage time. Selective reduction of part of the flour endogenous xylanase activity in dough by added TAXI reduced dough syruping after 12 and 20 days of storage by 50%, providing straightforward evidence for the involvement of xylanases and, thus, AX in the syruping phenomenon. Addition of xylanases with different inhibitor sensitivities [an inhibition-sensitive Bacillus subtilis xylanase (XBS(i)) as well as a noninhibited mutant (XBS(ni)) thereof] to dough confirmed the importance of xylanases in dough syruping, on one hand, and the power of wheat flour TAXI to constitute a significant barrier against xylanase-mediated dough syruping, on the other hand. Use of xylanases with different substrate selectivities [an Aspergillus aculeatusxylanase (XAA) versus XBS(ni)] showed degradation of water-extractable AX (WE-AX) and solubilized AX to low molecular weight molecules rather than the conversion of water-unextractable AX (WU-AX) to high molecular weight water extractable components to be the main factor influencing dough syruping.     

Causes of culling and death in sows.

Over a 4-year period, the annual number of culled sows in 9 Danish herds averaged 54.8 per cent of the year-sows and the number of culled sows in per cent of total number of farrowings averaged 25.8 (Table I). -- The culling rate varied considerably from herd to herd within the same year and from year to year (Tables I and II); however, the average annual culling rate for all the herds only presented small variations (Table II). The average number of litters reared per sow before culling was 3.6. The culling rate was higher in pedigree herds than in commercial herds, and it was highest in the small pedigree herds (Table III). The hygiene level in the herds and the introduction of new female breeding stock did not influence the culling rate (Table IV). A proportionally lower percentage of the sows was culled in herds where the dry and pregnant sows were housed in stalls and/or were tethered, as compared to herds where these sows were housed in pens (Table V). -- The culling rate in the age groups of sows with less than 8 farrowings remained at approximately the same level (Table VI). The main reason for culling was infertility problems, which were recorded in 41.4 per cent of the culled sows, while 16.7 per cent of the sows were culled because their litters were poor and/or small (Table VII). The mortality rate among the culled sows was 11.9 (Table VII), and the main causes of death were chronic pyogenic infections, which occurred in 25.5 per cent of the fatal cases (Table VIII). Certain aspects concerning the recording and calculation of culling rates in the different herds are discussed and it is emphasized that the culling rate per se may not have any direct relationship to the productivity in the herd.