Carbon mineralization of Chinese fir (Cunninghamia lanceolata) soils under different temperature and humidity conditions

Burned and unburned mineral soils (0–10 cm) from a 40-year-old Chinese fir (Cunninghamia lanceolata) forest in Nanping, Fujian, China were incubated for 90 days at different temperatures (25 °C and 35 °C) and humidity [25%, 50%, and 75% of water holding capacity (WHC)] conditions. Carbon (C) mineralization of all soils was determined using CO₂ respiration method. The results showed that CO₂ evolution rates of the burned and control soils exhibited similar temporal patterns, and similar responses to temperature and moisture. CO₂ evolution rates for all soil samples decreased with incubation time. At different humidity conditions, average rate of C mineralization and cumulative mineralized C from burned and control soils were significantly higher at 35 °C than at 25 °C. This implied that C mineralization was less sensitive to soil moisture than to temperature. In both soils at 25 °C or 35 °C, the amount of soil evolved CO₂ over the 90 days incubation increased with increasing moisture content from 25% to 75% WHC. A temperature coefficient (Q₁₀) varied with soil moisture contents. The maximum values recorded for Q₁₀ were 1.7 in control soil and 1.6 in burned soil both at 25% WHC. However, there were no significant differences in Q₁₀ values between the control and burned soils over all moisture ranges (P > 0.05). The data of cumulative C–CO₂ released from control and burned soils were fitted to two different kinetic models. The two simultaneous reactions model described mineralization better than the first-order exponential model, which reflected the heterogeneity of substrate quality. Based on these results, it is possible to conclude that temperature and moisture are important in the controls of C mineralization, and the combined effects of these variables need to be considered to understand and predict the response of CO₂ release in subtropical ecosystems to climate change.     

The systematic position of Hoplitomerycidae (Ruminantia) revisited

Hoplitomeryx Leinders was originally described only on cranial characters. The type specimens were found during the 1970's in karstic fissure fillings, most likely of Messinian age, in Gargano (Apulia, southeastern Italy), between Poggio Imperiale (41°49′30′ N, 15°21′58′ E) and Apricena (41°47′06′ N, 15°26′41′ E). During the 1990's, Hoplitomeryx remains were also discovered in the lower Tortonian layered calcarenites near Scontrone (Abruzzo, central Italy; 41°45′15.55′ N, 14°02′13.23′ E). The skull fragments, teeth, and jawbones from both localities have been examined. The dental characters had never been described before, and also some maxillaries and jawbones were not part of the original sample that was analyzed to establish the genus. Because they possess two lacrimal orifices and closed metatarsal gulley, hoplitomerycids have been linked more closely with Cervids, and accommodated in Cervoidea. A cladistic analysis of a character-taxon matrix of 121 morphological features (48 cranial, 51 dental and 22 postcranial characters) is performed. The analysis shows that hoplitomerycids stem either between antilocaprids and bovids, or antilocaprids and giraffids. They are not linked directly with cervids. Hoplitomerycids likely stemmed from a primitive ruminant stock, perhaps around 29 Ma when a land bridge connected the Abruzzo-Apulia platform with the Balkans across the Adriatic Sea. In the new land, hoplitomerycids developed a mosaic of apomorphic and homoplastic (convergent) character states that recall those found in other higher ruminants.     

Regulating effects of climate,net primary productivity,and nitrogen on carbon sequestration rates in temperate wetlands,Northeast China

Temperate wetlands in the Northern Hemisphere have high long-term carbon sequestration rates, and play critical roles in mitigating regional and global atmospheric CO₂ increases at the century timescale. We measured soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) from 11 typical freshwater wetlands (Heilongjiang Province) and one saline wetland (Jilin Province) in Northeast China, and estimated carbon sequestration rates using ²¹⁰Pb and ¹³⁷Cs dating technology. Effects of climate, net primary productivity, and nutrient availability on carbon sequestration rates (R_carbon) were also evaluated. Chronological results showed that surface soil within the 0–40 cm depth formed during the past 70–205 years. Soil accretion rates ranged from 2.20 to 5.83 mm yr⁻¹, with an average of 3.84 ± 1.25 mm yr⁻¹ (mean ± SD). R_carbon ranged from 61.60 to 318.5 gC m⁻² yr⁻¹ and was significantly different among wetland types. Average R_carbon was 202.7 gC m⁻² yr⁻¹ in the freshwater wetlands and 61.6 gC m⁻² yr⁻¹ in the saline marsh. About 1.04 × 10⁸ tons of carbon was estimated to be captured by temperate wetland soils annually in Heilongjiang Province (in the scope of 45.381–51.085°N, 125.132–132.324°E). Correlation analysis showed little impact of net primary productivity (NPP) and soil nutrient contents on R_carbon, whereas climate, specifically the combined dynamics of temperature and precipitation, was the predominant factor affecting R_carbon. The negative relationship observed between R_carbon and annual mean temperature (T) indicates that warming in Northeast China could reduce R_carbon. Significant positive relationships were observed between annual precipitation (P), the hydrothermal coefficient (defined as P/AT, where AT was accumulative temperature ≥10 °C), and R_carbon, indicating that a cold, humid climate would enhance R_carbon. Current climate change in Northeast China, characterized by warming and drought, may form positive feedbacks with R_carbon in temperate wetlands and accelerate carbon loss from wetland soils.     

Enzymatic hydrolysis of rice straw and corn stalks for monosugars production

Rice straw and corn stalks were used as fermentation substrate for the evaluation of cellulases activity secreted by different organisms. The substrates were pretreated with alkaline hydrogen peroxide (AHP) for 6 h at 30 and 60 °C. From the fermentation studies, rice straw and corn stalks substrates showed the highest cellulases activity after 96 h at 60 °C of pre-treatment.     

Environmental indicators for estimating the potential soil respiration rate in alpine zone

Soil respiration is the main form of carbon flux from soil to atmosphere in the global carbon cycle. The effect of temperature on soil respiration rate is important in evaluating the potential feedback of soil organic carbon to global warming. We incubated soils from the alpine meadow zone and upper rocky zone along an altitudinal gradient (4400–5500 m a.s.l.) on the Tibetan Plateau under various temperature and soil moisture conditions. We evaluated the potential effects of temperature and soil moisture on soil respiration and its variation across altitudes. Soil respiration rates increased as the temperature increased. At 60% of soil water content, they averaged 0.21–5.33 μmol g soil⁻¹ day⁻¹ in the alpine meadow zone and 0.11–0.50 μmol g soil⁻¹ day⁻¹ in the rocky zone over the experimental temperature range. Soil respiration rates in the rocky zone did not increase between 25 and 35 °C, probably because of heat stress. Rates of decomposition of organic matter were high in the rocky zone, where the CN ratio was smaller than in the middle altitudes. Soil respiration rates also increased with increasing soil water content from 10% to 80% at 15 °C, averaging 0.04–2.00 μmol g soil⁻¹ day⁻¹ in the alpine meadow zone and 0.03–0.35 μmol g soil⁻¹ day⁻¹ in the rocky zone. Maximum respiration rates were obtained in the middle part of the alpine slope in any case of experimental temperature and soil moisture. The change patterns in soil respiration rate along altitude showed similar change pattern in soil carbon content. Although the altitude is a variable including various environmental factors, it might be used as a surrogate parameter of soil carbon content in alpine zone. Results suggest that temperature, soil moisture and altitude are used as appropriate environmental indicators for estimating the spatial distribution of potential soil respiration in alpine zone.     

Stress responses and specific metal exclusion on mine soils based on germination and growth studies by Australian golden wattle

We reported the Australian golden wattle as a copper stabilizer in abandoned copper mine soils earlier. Here we investigate to confirm this plant’s suitability to grow on metal contaminated mine soils based on stress indication. The seeds of Acacia pycnantha collected from mining area were germinated after heat and no heat treatment on two types of irrigation. The daily irrigated and heat treated seeds gave up to 85% germination on sandy soil. The A. pycnantha was grown under greenhouse condition in six different soils collected from abandoned copper mine at Kapunda in South Australia. Among the six soil samples, soil-1 with the highest copper concentration produced 2.05 mmol g⁻¹ tissue of proline. Proline expression was prominent in more saline soils (1, 5 and 6) having electrical conductivity (EC) 1184, 1364 and 1256 μS, respectively. Chlorophyll a, b and carotenoid levels in plants showed a gradually decreasing trend in all the soils as experiment progressed. The plants grown on soil sample-1, containing 4083 ± 103 mg kg⁻¹ of copper resulted in 18 ± 2 mg kg⁻¹ accumulation in its leaf. The calcium accumulation was significant up to 11648 ± 1209 mg kg⁻¹ in leaf. Although pore water samples showed higher Cu concentration in soils, an increased mobility of arsenic and lead was observed in all the soil samples. Our experiment points out the need for proper monitoring of revegetation processes to avoid revegetation and reclamation failure.     

The effect of acclimation temperature on thermal activity thresholds in polar terrestrial invertebrates

In the Maritime Antarctic and High Arctic, soil microhabitat temperatures throughout the year typically range between ?10 and +5 °C. However, on occasion, they can exceed 20 °C, and these instances are likely to increase and intensify as a result of climate warming. Remaining active under both cool and warm conditions is therefore important for polar terrestrial invertebrates if they are to forage, reproduce and maximise their fitness. In the current study, lower and upper thermal activity thresholds were investigated in the polar Collembola, Megaphorura arctica and Cryptopygus antarcticus, and the mite, Alaskozetes antarcticus. Specifically, the effect of acclimation on these traits was explored. Sub-zero activity was exhibited in all three species, at temperatures as low as ?4.6 °C in A. antarcticus. At high temperatures, all three species had capacity for activity above 30 °C and were most active at 25 °C. This indicates a comparable spread of temperatures across which activity can occur to that seen in temperate and tropical species, but with the activity window shifted towards lower temperatures. In all three species following one month acclimation at ?2 °C, chill coma (=the temperature at which movement and activity cease) and the critical thermal minimum (=low temperature at which coordination is no longer shown) occurred at lower temperatures than for individuals maintained at +4 °C (except for the CTmin of M. arctica). Individuals acclimated at +9 °C conversely showed little change in their chill coma or CTmin. A similar trend was demonstrated for the heat coma and critical thermal maximum (CTmax) of all species. Following one month at ?2 °C, the heat coma and CTmax were reduced as compared with +4 °C reared individuals, whereas the heat coma and CTmax of individuals acclimated at +9 °C showed little adjustment. The data obtained suggest these invertebrates are able to take maximum advantage of the short growing season and have some capacity, in spite of limited plasticity at high temperatures, to cope with climate change.     

Determination of optimal conditions for hydrolysis of conjugated deoxynivalenol in corn and wheat with trifluoromethanesulfonic acid

Deoxynivalenol (DON) is a common mycotoxin contaminating corn and wheat and conjugated forms are also present. Recent studies have suggested that current analytical methods for DON analysis in feedstuffs do not detect conjugated forms in the absence of hydrolysis. The aim of the current study, therefore, was to determine the optimal conditions in which conjugated DON in corn and wheat can be hydrolyzed by trifluoromethanesulfonic acid (TFMSA). The optimal hydrolysis procedure was determined based on reaction duration, reaction temperature and TFMSA concentration. Total DON concentrations were determined using ELISA with free DON concentrations determined by ELISA and GC–MS. The optimal hydrolysis conditions for determination of conjugated DON in corn were found to be 0.5 M TFMSA incubated for 20 min at 22 °C. Optimal conditions for wheat samples were 0.5 M TFMSA incubated for 40 min at 40 °C. Using these optimal hydrolysis conditions, 10 corn samples and 10 wheat samples were analyzed to determine the presence of conjugated DON. All samples contained conjugated DON with an increase of 8–70% for DON in corn following hydrolysis and an increase of 7–75% for DON in wheat. This hydrolysis procedure will aid in the accurate determination of total DON and conjugated DON in feedstuffs.     

Variability of sea-surface temperature and sea-ice cover in the Fram Strait over the last two millennia

A sediment core located on the West Spitzbergen margin in the Fram Strait (78°54.931′N, 6°46.005′E, water depth: 1497 m) was analyzed for its dinocyst content in order to reconstruct hydroclimatic variations of the last 2500 years. The relative abundance of dinocyst taxa and principal component analysis show a major transition at about 300 cal. years BP. It is characterized by the disappearance of thermophilic taxa Spiniferites mirabilis-hyperacanthus and Impagidinium sphaericum and the increase of polar–subpolar taxa Impagidinium pallidum and Pentapharsodinium dalei. Sea-surface temperature (SST) estimates suggest warmer conditions than present (anomaly～+2 °C) averaging at 7 °C in summer until 300 cal. years BP, although cooling pulses are recorded around 1700, 1500, 1200 and 800 cal. years BP. The last 300 years were marked by a cooling from 7.6 to 3.5 °C and sea-ice cover increasing up to 7 months/yr. The results demonstrate that the Fram Strait area is sensitive to hydroclimatic variations, notably with respect to sea-ice and SSTs, which are linked to the relative strength of northward flow of North Atlantic waters to the East and southward outflow of cold and fresh waters from the Arctic Ocean. Based on our data, the warmest part of our record around 1320 cal. years BP is the only interval of the last 2500 years that provides a possible analogue for the modern post-AD 2000 interval, which is characterized by sea-ice free conditions.     

Assessment of hydrocarbon biodegradability in clayed and weathered polluted soils

Hydrocarbon biodegradation in clayed and weathered polluted soils is a challenge; thus the aim of the present study was to determine the best experimental conditions that improve the hydrocarbon biodegradability in clayed and weathered polluted soils, modifying the nitrogen and phosphorous content considering the C:N:P ratio and the water content as a percentage of the water-holding capacity of the soil. Biodegradation tests were performed in microcosms containing 20 g of dry soil at 30 °C. A uniform-precision central composite design of second order with three levels was used to assess the effect of nutrient and water content adjustment on the hydrocarbon degradation rate, total carbon consumption, and microbial activity. The results showed that the water-holding capacity corresponding to 350% and a C:N:P ratio of 100:7.5:0.66 were the best experimental conditions for obtaining the highest hydrocarbon degradation rate (1145 mg TPH kg^?1 dry soil day^?1), whereas the hydrocarbon degradation rate in a non-stimulated control was only 129 mg TPH kg^?1 dry soil day^?1. Water content was the factor that showed the highest significant effect (p ≤ 0.05) on the hydrocarbon degradation rate. The results of the present study allowed the achievement of the best experimental conditions that enhance hydrocarbon biodegradability in clayed and weathered polluted soils. Also, these conditions are proposed for use as a biodegradability assay.     

Chytrids cannot survive at high temperatures in liquid growth media: implications for soil ecosystems

Sixteen isolates in the orders Blastocladiales, Chytridiales, Rhizophydiales and Spizellomycetales were incubated for 2 d in liquid PYG growth medium at 33, 37, 40, 45 and 50 °C. These fungi could not resume growth when returned to 20 °C if the temperature of incubation was more than a few degrees above the maximum temperature for growth on solid PYG growth medium. The maximum temperatures for survival of some chytrids are probably close to the temperatures reached periodically on the surface of moist soils in warm climates. Desiccated thalli of chytrids in the Blastocladiales and Spizellomycetales can survive much higher temperatures than chytrids in the Chytridiales and Rhizophydiales. Therefore, the maximum temperature and moisture content of the soil could significantly affect the diversity of chytrids in the ecosystem.     

Formation of di-d-fructofuranose-1,2′:2,1′-dianhydride by three novel inulin fructotransferases from the Nocardiaceae family

In this work, three novel genes encoding di-d-fructofuranose-1,2′:2,1′-dianhydride (DFA I)-forming inulin fructotransferases (IFTases) from Nocardiaceae family, including Nocardioides luteus, Nocardioides sp. JS614, and Nocardioidaceae bacterium Broad-1, were cloned and expressed in Escherichia coli. The recombinant IFTases from N. luteus (NoluIFTase), Nocardioides sp. JS614 (NospIFTase), and N. bacterium Broad-1 (NobaIFTase) were purified, identified, and characterized. SDS-PAGE analysis showed that they had molecular weights of approximately 41–42 kDa, while gel filtration analysis indicated that their native molecular weights ranged from 50 to 62 kDa, suggesting that the three enzymes may be monomers. Their optimum pH values ranged from 5.5 to 6.0, similar to other DFA I-forming IFTases or di-d-fructofuranose-1,2′:2,3′-dianhydride (DFA III)-forming IFTases. NoluIFTase, NospIFTase, and NobaIFTase exhibited maximal activities at 55 °C, 50 °C, and 45 °C and were stable at 70 °C (for 15 min), 70 °C (187 min), and 55 °C (239 min), respectively. Furthermore, by comparing with our previously reported DFA I-forming IFTase, namely CcIFTase, a probable mechanism for the formation of DFA I by the three new enzymes was speculated, and CcIFTase will be selected for future structural resolution to illustrate the catalytic mechanism of DFA I-forming IFTases toward inulin.     

Size exclusion chromatography of zein and xanthophylls: Optimization of operating parameters

Ethanol-soluble components of corn (zein and xanthophylls) were separated and purified by size exclusion chromatography. Aqueous ethanol was used as the solvent for the entire process from extraction through chromatography. The effect of operating and design parameters, such as temperature, flow rate, loading mass, loading volume, column height and diameter, on productivity and resolution of the components was studied. Using a one-variable-at-a-time (OVAT) approach with 1 cm × 60 cm columns, optimum conditions were determined to be 40 °C temperature, 0.25 mL/min flow rate, volume loading of 22 mL corn extract, mass loading at 70 g/L of corn extract. All components could be resolved with base line separation with a 240 cm column length. Column diameter did not affect separation, implying linear scalability with constant flow distribution.     

Similar metabolic rate-temperature relationships after acclimation at constant and fluctuating temperatures in caterpillars of a sub-Antarctic moth

Temperature compensation in whole-animal metabolic rate is one of the responses thought, controversially, to characterize insects from low temperature environments. Temperature compensation may either involve a change in absolute values of metabolic rates or a change in the slope of the metabolic rate – temperature relationship. Moreover, assessments of compensation may be complicated by animal responses to fluctuating temperatures. Here we examined whole animal metabolic rates, at 0 °C, 5 °C, 10 °C and 15 °C, in caterpillars of the sub-Antarctic moth, Pringleophaga marioni Viette (Tineidae), following one week acclimations to 5 °C, 10 °C and 15 °C, and fluctuating temperatures of 0–10 °C, 5–15 °C, and 10–20 °C. Over the short term, temperature compensation was found following acclimation to 5 °C, but the effect size was small (3–14%). By comparison with caterpillars of 13 other lepidopteran species, no effect of temperature compensation was present, with the relationship between metabolic rate and temperature having a Q₁₀ of 2 among species, and no effect of latitude on temperature-corrected metabolic rate. Fluctuating temperature acclimations for the most part had little effect compared with constant temperatures of the same mean value. Nonetheless, fluctuating temperatures of 5–15 °C resulted in lower metabolic rates at all test temperatures compared with constant 10 °C acclimation, in keeping with expectations from the literature. Absence of significant responses, or those of large effect, in metabolic rates in response to acclimation, may be a consequence of the unpredictable temperature variation over the short-term on sub-Antarctic Marion Island, to which P. marioni is endemic.     

Heat coma temperature,relative contents of saturated/unsaturated fatty acids and reproductive maturation in the oceanic sea skaters Halobates micans

This study was performed to clarify how the relative volume of saturated/unsaturated lipid and reproductive maturation relate to resistance to high temperature in the oceanic sea skaters, Halobates micans. Heat coma temperature (HCT) was measured in H. micans adults collected from a fixed sampling location (12°00′N, 135°00′E) in the western tropical Pacific Ocean. After measuring HCT, the specimen were dissected to measure the testes size and to determine the presence and number of oocytes in females. Bodies of the specimen were assessed by lipid analysis to evaluate saturated and unsaturated lipid content. A negative trend was seen between heat coma temperature and percentage of a saturated fatty acid, myristic acid (ratio of carbon number to number of double bonds = 14:0) (Pearson's correlation test: r = − 0.520, p = 0.101). In contrast, a positive trend was detected between heat coma temperature and percentage of an unsaturated fatty acid, palmitoleic acid (16:1) (r = 478, p = 0.137). Young males with small testes showed lower heat coma temperatures, whereas females that showed relatively high heat coma temperatures of 36–40 °C tended to have fewer mature oocytes in their ovaries than those that showed low heat coma temperatures of 30–34 °C. As Halobates appears to exhibit embryonic diapause rather than adult diapause, males of H. micans may develop both testes and resistance to high temperature in the parallel as they grow. In females, a trade-off may occur between heat tolerance function and oogenesis in the oceanic sea skaters.     

A reduced core to skin temperature gradient,not a critical core temperature,affects aerobic capacity in the heat

The purpose of this study was to determine the impact of the core to skin temperature gradient during incremental running to volitional fatigue across varying environmental conditions. A secondary aim was to determine if a “critical” core temperature would dictate volitional fatigue during running in the heat. 60 participants (n=49 male, n=11 female; 24±5 yrs, 177±11 cm, 75±13 kg) completed the study. Participants were uniformly stratified into a specific exercise temperature group (18 °C, 26 °C, 34 °C, or 42 °C) based on a 3-mile run performance. Participants were equipped with core and chest skin temperature sensors and a heart rate monitor, entered an environmental chamber (18 °C, 26 °C, 34 °C, or 42 °C), and rested in the seated position for 10 min before performing a walk/run to volitional exhaustion. Initial treadmill speed was 3.2 km h⁻¹ with a 0% grade. Every 3 min, starting with speed, speed and grade increased in an alternating pattern (speed increased by 0.805 km h⁻¹, grade increased by 0.5%). Time to volitional fatigue was longer for the 18 °C and 26 °C group compared to the 42 °C group, (58.1±9.3 and 62.6±6.5 min vs. 51.3±8.3 min, respectively, p<0.05). At the half-way point and finish, the core to skin gradient for the 18 °C and 26 °C groups was larger compared to 42 °C group (halfway: 2.6±0.7 and 2.0±0.6 vs. 1.3±0.5 for the 18 °C, 26 °C and 42 °C groups, respectively; finish: 3.3±0.7 and 3.5±1.1 vs. 2.1±0.9 for the 26 °C, 34 °C, and 42 °C groups, respectively, p<0.05). Sweat rate was lower in the 18 °C group compared to the 26 °C, 34 °C, and 42 °C groups, 3.6±1.3 vs. 7.2±3.0, 7.1±2.0, and 7.6±1.7 g m⁻² min⁻¹, respectively, p<0.05. There were no group differences in core temperature and heart rate response during the exercise trials. The current data demonstrate a 13% and 22% longer run time to exhaustion for the 18 °C and 26 °C group, respectively, compared to the 42 °C group despite no differences in beginning and ending core temperatures or baseline 3-mile run time. This capacity difference appears to result from a magnified core to skin gradient via an environmental temperature advantageous to convective heat loss, and in part from an increased sweat rate.     

Soil quality assessment of coastal wetlands in the Yellow River Delta of China based on the minimum data set

Little information is available to assess the dynamic changes in wetland soil quality in coastal regions, though it is essential for wetland conservation and management. Soil samples were collected in Suaeda salsa wetlands (SWs), Tamarix chinensis wetlands (TWs), Suaeda salsa–Tamarix chinensis wetlands (STWs), freshwater Phragmites australis wetlands (FPWs) and saltwater Phragmites australis wetlands (SPWs) in three sampling periods (i.e., summer and autumn of 2007 and spring of 2008). According to the flooding characteristics of these wetlands, the study area could be grouped into three sub-regions: short-term flooding region (STFR), seasonal flooding region (SFR) and tidal flooding region (TFR). Soil quality was evaluated using the soil quality index (SQI), which was calculated using the selected minimum data set (MDS) based on principal components analysis (PCA). Our results showed that soil salt content (SSC), total carbon (TC), magnesium (Mg), nitrate nitrogen (NO₃⁻-N) and total sulfur (TS) consisted of a MDS among 13 soil properties. The SQI values varied from 0.18 to 0.66 for all soil samples, of which the highest and lowest SQI values were observed in TFR. The average SQI values were significantly higher in summer (0.50 ± 0.13) than in spring (0.37 ± 0.13) and autumn (0.36 ± 0.11) in the whole study area (p < 0.05). The average SQI values followed the order STFR (0.44 ± 0.12) > TFR (0.41 ± 0.15) > SFR (0.35 ± 0.09) although no significant differences were observed among the three regions (p > 0.05). SPWs and SWs soils showed higher SQI values (0.50 ± 0.10 and 0.47 ± 0.15, respectively) than TWs (0.30 ± 0.08) soils (p < 0.05). The SSC was the dominant factor of soil quality with its proportion of 34.1% contributing to the SQI values, followed by TC (24.5%) and Mg (24.1%). Correlation analysis also showed that SQI values were significantly negatively correlated with SSC. SSC might be a characteristic indicator of wetland soil quality assessment in coastal regions. The findings of this study showed that the SQI based on MDS is a powerful tool for wetland soil quality assessment.     

Role of calcium in alleviating effect of salinity on germination of Phragmites karka seeds

Phragmites karka (Retz.) Trin, ex. steud, a perennial reed with creeping rhizome from the family Poaceae, is distributed as pure population in brackish water swamps. Populations primarily propagate using ramets but also produce numerous seeds which form part of the seed bank after dispersal and are exposed to extremes of temperature, drought, and salinity stress. Seeds were germinated under a range of salinity (0, 100, 200, 300, 400, 500 mM NaCl) and temperature (10/20 °C, 15/25 °C, 20/30 °C, 25/35 °C, night/day) regimes in 12 h light:12 h dark photoperiod or in complete darkness with 0, 5, 10, 25 mM CaCl₂. Salinity, absence of light and high temperature (25/35 °C) reduced germination while calcium generally reversed this effect, more so at cooler temperature regimes. Calcareous soil around Karachi would help alleviate the salinity effect on the germination of P. karka and facilitate its survival.     

A microcosm study on bioremediation of fenitrothion-contaminated soil using Burkholderia sp. FDS-1

Fenitrothion, a toxic organophosphorus pesticide, can build up the concentration of nitrophenolic compound in soils and hence needs to be removed. Burkholderia sp. FDS-1, a fenitrothion-degrading strain, was used in this work to study factors affecting its growth, and then evaluated for its capacity to degrade fenitrothion in soil microcosms. Minimal salt medium containing 1% (w/v) glucose was found to be a suitable carbon source for inoculum preparation. Various factors, including soil pH, temperature, initial fenitrothion concentration, and inoculum size influenced the degradation of fenitrothion. Microcosm studies performed with varying concentrations (1–200 mg kg⁻¹) of fenitrothion-spiked soils showed that strain FDS-1 could effectively degrade fenitrothion in the range of 1–50 mg kg⁻¹ soil. The addition of Burkholderia sp. FDS-1 at 2×10⁶ colony forming units g⁻¹ soil was found to be suitable for fenitrothion degradation over a temperature range of 20–40 °C and at a slight alkaline pH (7.5). The results indicate that strain FDS-1 has potential for use in bioremediation of fenitrothion and its metabolite-contaminated sites. This is a model study that could be used for decontamination of sites contaminated with other compounds.     

Novel l-adenosine analogs as cardioprotective agents

Two l-nucleosides, l-3′-amino-3′-deoxy-N⁶-dimethyladenosine (l-3′-ADMdA) 1, previously synthesized in our laboratory, and the novel l-3′-amino-3′-deoxy-N⁶-methyladenosine-5′-N-methyluronamide (l-3′-AM-MECA) 2 were evaluated in an ischemia/reperfusion model on Langendorff perfused mouse heart. l-3′-ADMdA 1 was found to enhance functional recovery from ischemia (32.2 ± 3.7 cm H₂O/s % rate pressure product, compared to 21.3 ± 1.4 for the control and 30.7 ± 3.4 for adenosine) and increase the time to onset of ischemic contracture (14.5 ± 0.9 min, compared to 10.5 ± 1.0 min for the control and 13.6 ± 0.6 min for adenosine) comparable to adenosine. Consistent with the functional recovery data, decreased infarction area was seen in the case of 1 (19.1 ± 8.4, compared to 40.5 ± 7.2% for the control and 11.5 ± 2.1% for adenosine). In contrast, l-3′-AM-MECA 2 did not show significant functional recovery, increased onset of contracture, nor decreased infarction area compared to control. Unlike adenosine, neither 1 nor 2 induced cardiac standstill in mouse heart.