Efficient synthesis and utilization of phenyl-substituted heteroaromatic carboxylic acids as aryl diketo acid isosteres in the design of novel HIV-1 integrase inhibitors

Three new types of aryl diketo acid (ADK) isosteres were designed by conversion of the biologically labile 1,3-diketo unit into heteroaromatic motif such as isoxazole, isothiazole, or 1H-pyrazole to improve the physicochemical property of ADK-based HIV-1

Quantitative analysis of land mammal zoogeographical regions in China and adjacent regions

Quantitative analysis of land mammal zoogeographical regions in China and adjacent regions. Zoological Studies 43(1): 142-160. In this paper, our aim was to determine, by means of quantitative analysis, the distribution patterns of the land mammals in China and, adjacent regions using physiographical regions as operative geographical units (OGUs). Based, on the pre-sence or absence of 11 orders, 42 families, 197 genera, and 577 species of land mammals in their zoogeographical regions, which were used as OGUs, we studied the biotic boundary between the Oriental Region (OR) and the Palaearctic Region (PR), as well as subregion boundaries. The boundary's statistical significance was tested by G-test as described by McCoy et al. A significantly strong biotic boundary was found to separate the PR from the OR, and there is a weak biotic boundary in the PR, which divides it into 2 subregions. We concluded that the biotic boundary which separates the PR and OR is a strong boundary. We suggest that the Qinghai-Xizang Plateau should be regarded as a subregion of the PR, which can embody its characteristics of high elevations and a frigid climatic, which is called the Qing-Zang subregion of the PR (QZSP).

Foraging habitats and utilization distributions of Black-necked Cranes wintering at the Napahai Wetland, China

One of the most endangered populations of Black-necked Cranes (Grus nigricollis), the central population, is declining due to habitat loss and degradation, but little is known about their space use patterns and habitat preferences. We examined the space use and habitat preferences of Black-necked Cranes during the winter of 2007-2008 at the Napahai wetland in northwest Yunnan, China, where approximately 300 Black-necked Cranes (>90% of the total central population) spent the winter. Euclidean distance analysis was employed to determine the habitat preferences of Black-necked Cranes, and a local nearest-neighbor, convex-hull construction method was used to examine space use. Our results indicate that Black-necked Cranes preferred shallow marsh and wet meadow habitats and avoided farmland and dry grassland. Core-use areas (50% isopleths) and total-use areas (100% isopleths) accounted for only 1.2% and 28.2% of the study area, respectively. We recommend that habitat protection efforts focus on shallow marsh and wet meadow habitats to maintain preferred foraging sites. Core-use areas, such as the primary foraging areas of Black-necked Cranes, should be designated as part of the core zone of the nature reserve. Monthly shifts in the core-use areas of the cranes also indicate that the reserve should be large enough to permit changes in space use. In addition to preserving habitat, government officials should also take measures to decrease human activity in areas used by foraging Black-necked Cranes.

The influence of topography and land use on water quality of Xiangxi River in Three Gorges Reservoir region

A self-organizing map (SOM) was used to cluster the water quality data of Xiangxi River in the Three Gorges Reservoir region. The results showed that 81 sampling sites could be divided into several groups representing different land use types. The forest dominated region had low concentrations of most nutrient variables except COD, whereas the agricultural region had high concentrations of NO3N, TN, Alkalinity, and Hardness. The sites downstream of an urban area were high in NH3N, NO2N, PO4P and TP. Redundancy analysis was used to identify the individual effects of topography and land use on river water quality. The results revealed that the watershed factors accounted for 61.7% variations of water quality in the Xiangxi River. Specifically, topographical characteristics explained 26.0% variations of water quality, land use explained 10.2%, and topography and land use together explained 25.5%. More than 50% of the variation in most water quality variables was explained by watershed characteristics. However, water quality variables which are strongly influenced by urban and industrial point source pollution (NH3N, NO2N, PO4P and TP) were not as well correlated with watershed characteristics.

Nitrite utilization by Chaetoceros muelleri under elevated CO2 concentration

Chaetoceros muelleri (Lemn.) was cultured with nitrite (NO2-) or nitrate (NO3-) as the sole nitrogen source and aerated with air or with CO2-enriched air. Cells of C. muelleri excreted into the medium nitrite produced by reduction of nitrate when grown with 100 mu M NaNO3 as nitrogen source. Accordingly, NO2- concentration reached 10.4 mu M after 95 h at the low CO2 condition (aerated with air); while the maximum NO2- concentration was only around 2.0 mu M at the high CO2 condition (aerated with 5% CO2 in air), furthermore, after 30 h it decreased to no more than 1.0 mu M. NO2- was almost assimilated in 80 h when C. muelleri was cultured at the high CO2 condition with 100 mu M NaNO2 as sole nitrogen source. At the high CO2 condition, after 3 h the activity of nitrite reductase was as much as 50% higher than that at the low CO2 condition. It was indicated that enriched CO2 concentration could inhibit nitrite excretion and enhance nitrite assimilation by cells. Therefore, aeration with enriched CO2 might be an effective way to control nitrite content in aquaculture systems.

Effect of dietary carbohydrate-to-lipid ratios on growth and feed utilization in Chinese longsnout catfish (Leiocassis longirostris Gunther)

An 8-week growth trial was carried out in a semi-recirculation system at 26 +/- 0.5 degrees C to investigate the optimal dietary carbohydrate-to-lipid (CHO:L) ratio for carnivorous Chinese longsnout catfish (Leiocassis longirostris Gunther). Triplicate tanks of fish were assigned to each of five isocaloric and isonitrogenous diets with different carbohydrate-to-lipid ratios (0.75, 1.48, 1.98, 2.99 and 5.07). The results showed that a higher specific growth rate (SGR) and feed rate (FR) were observed in the fish fed diet ratios of 1.98 CHO:L (P < 0.05). Overloading dietary carbohydrate (5.07 CHO:L ratio) caused skeletal malformations. Apparent digestibility of dry matter (ADC(d)) significantly increased with dietary CHO:L ratio (P < 0.05), while significantly higher apparent digestibility of protein (ADC(p)) and apparent digestibility of energy (ACD(e)) was observed only in the 1.98 CHO:L group (P < 0.05). Whole body contents of dry matter, lipid and energy significantly increased as the CHO:L ratio decreased (P < 0.05). The hepatosomatic index (HSI) was highest at 1.98 CHO:L ratio (P < 0.05). Highest dietary CHO:L ratio resulted in lower liver glycogen, liver lipid, plasma glucose and plasma triacylglycerol (P < 0.05), whereas there was no significant difference in plasma total cholesterol (P > 0.05). High dietary CHO:L ratio caused pathological changes in fish morphology and liver histology. Based on maximum growth, the optimal carbohydrate-to-lipid ratio was 1.98 for Chinese longsnout catfish.

Photosynthetic inorganic carbon utilization of gametophytes and sporophytes of Undaria pinnatifida (Phaeophyceae)

The characteristics of inorganic carbon assimilation by photosynthesis were investigated in male and female gametophytes and juvenile sporophytes of Undaria pinnatifida. Gametophytes and sporophytes have detectable extracellular and intracellular carbonic anhydrase (CA) activity, and the CA inhibitor, acetazolamide (AZ), significantly inhibited their photosynthesis O-2 evolution. In pH-drift experiments, it was found that gametophytes did not raise the final pH of seawater above 9.00 (CO2 concentrations of about 2.2 mu M), indicating a low ability to utilize inorganic carbon. In contrast, sporophytes rapidly raised pH to over 9.53 and depleted the free CO2 Concentration to less than 0.16 mu M. The apparent photosynthetic affinity for CO2 was almost the same for gametophytes and sporophytes, whereas gametophytes had a much lower affinity for HCO3- than sporophytes. Two inhibitors of band 3 anion exchange protein (DIDS and SITS) inhibited the photosynthesis of gametophytes but not that of sporophytes. It was indicated that both gametophytes and sporophytes were capable of using HCO3-, which involved the external CA activity, and a direct HCO3- use also occurred in the former, but the latter showed a greater capacity of HCO3- use than the former. In addition, male and female gametophytes did not show great differences in the inorganic carbon uptake mechanism underlying photosynthesis.

Land-cover changes in an urban lake watershed in a mega-city, Central China

Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity.

Effect of dietary carbohydrate sources on growth performance and utilization for gibel carp (Carassius auratus gibelio) and Chinese longsnout catfish (Leiocassis longirostris Gunther)

The nutritional function of monosaccharides, disaccharides and polysaccharides for omnivorous gibel carp and carnivorous Chinese longsnout catfish were investigated and the ability of these two species to utilize carbohydrates was compared. For each species, triplicate groups of fish were assigned to each of five groups of isoenergetic and isonitrogenous experimental diets with different carbohydrate sources: glucose, sucrose, dextrin, soluble starch (acid-modified starch) and alpha-cellulose. The carbohydrates were included at 60 g kg(-1) in Chinese longsnout catfish diets and at 200 g kg(-1) in gibel carp diets. A growth trial was carried out in a recirculation system at 27.8 +/- 1.9 degrees C for 8 weeks. The results showed that fish with different food habits showed difference in the utilization of carbohydrate sources. For gibel carp, better specific growth rate (SGR) and feed efficiency (FE) were observed in fish fed diets containing soluble starch and cellulose, but for Chinese longsnout catfish, better SGR and FE were observed in fish fed diets containing dextrin and sucrose. Apparent digestibility coefficient of dry matter (ADC(d)) and apparent digestibility coefficient of energy (ADC(e)) were significantly affected by dietary carbohydrate sources in gibel carp. ADC(d) and ADC(e) significantly decreased as dietary carbohydrate complexity increased in Chinese longsnout catfish except that glucose diet had medium ADC(d) and ADC(e). In both species, no significant difference of apparent digestibility coefficient of protein was observed between different carbohydrate sources. Dietary carbohydrate sources significantly affected body composition, and liver phosphoenolpyruvate carboxykinase (PEPCK), pyruvate kinase (PK), glucose 6-phosphate dehydrogenase (G6PD) and malic enzyme (ME) activities also varied according to dietary carbohydrate complexity. Fish with different food habits showed different abilities to synthesize liver glycogen, and the liver glycogen content in gibel carp was significantly higher than in Chinese longsnout catfish. The influence of carbohydrate source on gluconeogenesis and lipogenesis was also different in the two fish species.

Effect of replacement of dietary fish meal by meat and bone meal and poultry by-product meal on growth and feed utilization of gibel carp, Carassius auratus gibelio

Triplicate groups of gibel carp Carassius auratus gibelio (initial body weight: 5.25 +/- 0.02 g) were fed for 8 weeks at 20-25 degreesC on five isonitrogenous (crude protein: 400 g kg(-1)) and isoenergetic diets (gross energy: 17 kJ g(-1)). Meat and bone meal (MBM) or poultry by-product meal (PBM) were used to replace fish meal at different levels of protein. The control diet contained fish meal as the sole protein source. In the other four diets, 150 or 500 g kg(-1) of fish meal protein was substituted by MBM (MBM15, MBM50) or PBM (PBM15, PBM50). The results showed that feeding rate for the MBM50 group was significantly higher than for other groups except the PBM50 group (P < 0.05). Growth rate in the MBM15 group was significantly higher than that in the control (P < 0.05), while there was no significant difference in growth between the control and other groups (P > 0.05). Feed efficiency and protein efficiency ratio in MBM50 was significantly lower while that in MBM15 was significantly higher (P < 0.05). Replacement of fish meal by MBM at 500 g kg(-1) protein significantly decreased apparent dry matter digestibility (ADC(D)) and gross energy (ADC(E)) while apparent protein digestibility (ADC(P)) was significantly decreased by the replacement of MBM or PBM (P < 0.05). The results suggest that MBM and PBM could replace up to 500 g kg(-1) of fish meal protein in diets for gibel carp without negative effects on growth while 150 g kg(-1) replacement by MBM protein improved feed utilization.

Comparative study on the effect of dietary lipid level on growth and feed utilization for gibel carp (Carassius auratus gibelio) and Chinese longsnout catfish (Leiocassis longirostris Gunther)

An 8-week growth trial investigated the effect of dietary lipid level on growth performance of a carnivorous fish, Chinese longsnout catfish (Leiocassis longirostris Gunther) and an omnivorous fish, gibel carp (Carassius auratus gibelio). For each species, seven isonitrogenous semi-purified diets (455 g kg(-1) crude protein for Chinese longsnout catfish and 385 g kg(-1) crude protein for gibel carp) were formulated to contain 30, 60, 90, 120, 150, 180 or 210 g kg(-1) lipid. For Chinese longsnout catfish, feed intake (FI) decreased with increasing dietary lipid and there was no significant difference in feed intake from 90 to 210 g kg(-1) lipid. Specific growth rate (SGR) increased with dietary lipid level (P < 0.05) and the 150 and 180 g kg(-1) groups were the best. Feed conversion efficiency (FCE), protein retention efficiency (PRE) and energy retention efficiency (ERE) were higher at 180 g kg(-1) lipid. For gibel carp, FI decreased with increased dietary lipid and 180 and 210 g kg(-1) lipid groups showed lower values. SGR increased with dietary lipid level and the 150 and 180 g kg(-1) were the best. FCE was higher at 180 g kg(-1) lipid level. PRE increased with dietary lipid level and there was no significant difference in groups from 120 to 210 g kg(-1) dietary lipid. ERE increased with increasing dietary lipid level, and groups fed 120, 150 and 180 g kg(-1) lipid showed the highest values. In Chinese longsnout catfish, increase in dietary lipid level, resulted in increased carcass dry matter, crude protein, crude lipid and gross energy. In gibel carp, dry matter, crude protein, and crude lipid increased with dietary lipid level. Based on regression between SGR and dietary lipid, dietary lipid requirements for Chinese longsnout catfish and gibel carp were 142.6 and 140.5 g kg(-1), respectively.

Photosynthetic utilization of inorganic carbon in the economic brown alga, Hizikia Fusiforme (Sargassaceae) from the South China Sea

The mechanism of inorganic carbon (C-i) acquisition by the economic brown macroalga, Hizikia fusiforme (Harv.) Okamura (Sargassaceae), was investigated to characterize its photosynthetic physiology. Both intracellular and extracellular carbonic anhydrase (CA) were detected, with the external CA activity accounting for about 5% of the total. Hizikia fusiforme showed higher rates of photosynthetic oxygen evolution at alkaline pH than those theoretically derived from the rates of uncatalyzed CO2 production from bicarbonate and exhibited a high pH compensation point (pH 9.66). The external CA inhibitor, acetazolamide, significantly depressed the photosynthetic oxygen evolution, whereas the anion-exchanger inhibitor 4,4'-diisothiocyano-stilbene-2,2'-disulfonate had no inhibitory effect on it, implying the alga was capable of using HCO3- as a source of C-i for its photosynthesis via the mediation of the external CA. CO2 concentrations in the culture media affected its photosynthetic properties. A high level of CO2 (10,000 ppmv) resulted in a decrease in the external CA activity; however, a low CO2 level (20 ppmv) led to no changes in the external CA activity but raised the intracellular CA activity. Parallel to the reduction in the external CA activity at the high CO2 was a reduction in the photosynthetic CO2 affinity. Decreased activity of the external CA in the high CO2 grown samples led to reduced sensitiveness of photosynthesis to the addition of acetazolamide at alkaline pH. It was clearly indicated that H. fusiforme, which showed CO2-limited photosynthesis with the half-saturating concentration of C-i exceeding that of seawater, did not operate active HCO3- uptake but used it via the extracellular CA for its photosynthetic carbon fixation.