The objective of this study was to investigate the influence of the two antioxidants, ascorbic acid and (+)catechin, on the oxidation of 2'-deoxyguanosine (dG), using an iron-mediated Fenton reaction. The oxidation products 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and 8,5'-cyclo-2'-deoxyguanosine, together with the secondary oxidation products guanidinohydantoin and dehydro-guanidinohydantoin, were identified and quantified through the use of an LC-MS/MS system. The results obtained showed that catechin inhibited the oxidation better than ascorbic acid did, indicating that the chelating ability of catechin rather than the radical scavenging mechanism alone is vital for the observed antioxidative efficiency. The correlation between the different oxidation products was found to be quite low, primarily because of the instability of 8-oxodG, making it prone to further oxidation. This led to apparent anti- and pro-oxidative results being obtained, emphasizing the potential problems in evaluating oxidative stress, by use of a single marker. 相似文献
1. The tilapia Oreochromis niloticus baringoensis is a genetically and morphologically distinct sub‐species of Oreochromis niloticus endemic to Lake Baringo, Kenya. In recent years, concern has been expressed as to its status. Recent declines in catch returns suggest the population may be threatened, with conservation action required to safeguard it.
2. Catch returns from the Baringo fishery since 1964 have shown considerable fluctuations for all species, but especially O. n. baringoensis. From a peak of 712 t in 1970, their total catch was only 5 t in 2005, despite a 2 year period of closure in 2002 and 2003. Changes in fishery catch and relative abundance were independent of exploitation in the fishery but were significantly correlated with lake level.
3. Few individuals were captured at lengths >250 mm, with no fish sampled >284 mm. During periods of high lake level, individuals matured at smaller sizes and were capable of growing to larger ultimate sizes. With maturity at lengths <130 mm and fishery regulations preventing removal of fish <180 mm, there was a relatively large proportion of mature fish that was below exploitation size each year (19 to 44%). In most years, the proportion of fish available for exploitation was <10%.
4. Stable isotope analyses revealed O. n. baringoensis was reliant upon planktonic basal resources and zooplankton carbon. There was only minimal trophic overlap with other fish species in the lake, indicating little potential for competition for food resources.
5. These data suggest that the population status of O. n. baringoensis is not threatened per se, but subject to an unpredictable and unstable environment that strongly influences their life‐history traits and, ultimately, their population abundance, and should be managed accordingly.
1. The aim of the experiment was to investigate the effect of gaseous stunning methods on the carcase and meat quality of broilers (dead weight 1.0 to 2.3 kg) in comparison with electrical stunning.
2. Two replicates of broilers (age 54 and 59 d respectively) were stunned in carbon dioxide, in argon or by electric current, and the carcases were plucked either by a mechanical plucker or by hand.
3. Carcase and meat quality were evaluated to determine the effect of these stunning treatments and plucking methods. The quality factors measured included pH at 20 min post‐mortem, ultimate pH, texture and colour of the pectoralis major muscle, and the incidence of carcase appearance defects, cooking loss, broken bones and bruises in the breast and leg muscles.
4. Stunning method had a significant effect on pH at 20 min, ultimate pH, texture and colour of breast meat. Plucking method had a significant effect on the cooking loss and texture.
5. Argon stunning resulted in fewer muscle haemorrhages, a more rapid early post‐mortem fall in pH and more tender breast meat than in the electrically stunned broilers; carbon dioxide stunned broilers had intermediate values for pH decline and meat tenderness but were not significantly different from argon stunning regarding muscle haemorrhages.
6. Appearance defects occurred to a similar extent in all the stunning methods and mechanical plucking resulted in 4 times as many defects compared with hand plucking; the incidence of broken bones was higher in mechanically plucked broilers than in hand plucked carcases.
7. Gaseous stunning of broilers produced relatively better quality carcases and meat than electrical stunning, and therefore may have commercial advantages. 相似文献
1. The effects of age and sex have been studied on the proximate composition and inorganic constituents in breast, thigh, drumstick and skin from a commercial British broiler strain (Ross 1).
2. Protein content generally increased with age in all muscles and decreased in skin. Protein content in skin of males was always higher than that in females.
3. Moisture content in all muscles decreased with age. In the skin, moisture decreased with age considerably more in females than in males.
4. Fat content increased with age in all tissues, while ash content of breast, thigh and skin decreased with age.
5. Phosphorus, chloride, magnesium and potassium all decreased with age in all the tissues. Thigh and skin calcium content were affected by age, as was the sodium content of drumstick and skin.
6. The sex effect on the inorganic constituents was variable. 相似文献
Urinary proteins distinct from Bence Jones proteins, but sharing antigenic determinants, were found in the urine of a number of patients with multiple myeloma. These components were smaller in size and antigenically deficient compared with Bence Jones proteins. They were best detected with antiserums to the homologous Bence Jones proteins and, in some cases, were related to the variable portion of the Bence Jones protein molecule. 相似文献
The anion-exchange ability of layered double hydroxides (LDHs) has been exploited to create materials for use in catalysis, drug delivery, and environmental remediation. The specific cation arrangements in the hydroxide layers of hydrotalcite-like LDHs, of general formula Mg2+(1-x)Al3+(x)OH2(Anion(n-)(x/n)).yH2O, have, however, remained elusive, and their elucidation could enhance the functional optimization of these materials. We applied rapid (60 kilohertz) magic angle spinning (MAS) to obtain high-resolution hydrogen-1 nuclear magnetic resonance (1H NMR) spectra and characterize the magnesium and aluminum distribution. These data, in combination with 1H-27Al double-resonance and 25Mg triple-quantum MAS NMR data, show that the cations are fully ordered for magnesium:aluminum ratios of 2:1 and that at lower aluminum content, a nonrandom distribution of cations persists, with no Al3+-Al3+ close contacts. The application of rapid MAS NMR methods to investigate proton distributions in a wide range of materials is readily envisaged. 相似文献
The biodiversity of developing countries is increasingly threatened by introductions of invasive alien species. This study on the allodiversity in Lake Naivasha, Kenya reviews the pathways, establishment rates and outcomes of introduced species, and provides the basis for determining conservation actions that, if implemented, could prevent potentially harmful effects of similar events in other East African lakes. Introductions into Naivasha commenced in the 1920s with the release of a sport fish and have since produced an allodiversity of 23 species. This includes species that are no longer present (e.g., some tilapia species), presumed no longer present (e.g., the Nile perch Lates niloticus) or whose distribution is highly localised and ecologically neutral (e.g., the coypu Myocastor coypus). It also includes species that established successfully and invoked major changes in lake ecology (e.g., the red swamp crayfish Procambarus clarkii) and a species that is producing apparent economic benefits to the local population (i.e., the common carp Cyprinus carpio). The most frequent donor continents were the Americas and most species were the result of secondary introductions. The main introduction vector was active release that aimed to enhance fishery production. Alien species now dominate each main level of the lake’s food web and produce impacts that are rarely restricted to a single ecosystem service. With a few exceptions, the majority of introductions translate into socioeconomic costs that contribute to rising social conflicts and exacerbating poverty. Development of appropriate conservation management tools within a regulatory framework could help protect Naivasha from further damage and could be used elsewhere in East African lakes to ensure that subsequent introductions enhance ecosystem services without affecting biodiversity. 相似文献
CASE HISTORY A 15-year-old, brown-and-white cat was presented to a veterinary clinic with an ulcerated, reddened 1-cm diameter lesion on the nasal planum. CLINICAL FINDINGS AND DIAGNOSIS: Histology of a biopsy sample confirmed the lesion was a squamous cell carcinoma (SCC). PCR amplified DNA sequences from two different papillomaviruses. One sequence was from FdPV 2, which has previously been amplified from feline cutaneous SCC. However, the other sequence has not previously been reported, suggesting a novel feline papillomavirus. CLINICAL RELEVANCE: There is evidence that papillomaviruses promote the development of SCC on sun-exposed skin in humans. This is the first report in a cat of a papillomavirus other than FdPV2 and the first time that multiple papillomaviruses have been detected within a single neoplasm in this species. Whether the papillomaviruses influenced the development and behaviour of this SCC is currently uncertain, but this case provides additional evidence of the association between papillomaviruses and feline cutaneous SCC. If papillomaviruses are found to influence the development of SCC this may allow novel strategies to prevent these common neoplasms in cats. 相似文献