Objective:To ascertain analgesic,antibacterial and central nervous system(CNS)depressant activities of ethyl acetate,dichloromethane and carbon tetrachloride fractions of methanol extract of Albizia ...proceru(A.procera)leaves.Methods:Leaves extracts of A.procera were tested for analgesic activity by acetic acid induced and formalin test method in mice.The in vitro antibacterial activity was performed by agar well diffusion method.CNS depressant activity was evaluated by hole cross and open field tests.Results:All the extracts at 200 mg/kg exhibited significant(P<0.01)analgesic activity in acetic acid induced and formalin tests method in mice.Analgesic activity of the ethyl acetate fraction was almost same like as standard drug indomelhacin in acetic acid induced method.The CNS depressant activity of the extracts at 500 mg/kg was comparable to the positive control diazepam as determined by hole cross and open field test method.The extracts exhibited moderate antimicrobial activity against all the tested microorganisms(Staphylococcus aureus,Bacillus cereus,Pseudomonas aeruginosa,Esherichia coli,Shigetta soneii.Shigella boydii)at concentration of 0.8 mg/disc.The measured diameter of zone of inhibition for the extracts was within the range of 7 to 12 mm which was less than the standard kanamycin(16-24 mm).Conclusions:It is concluded that all the extracts possess potential analgesic and CNS depressants activity.This study also showed that different fractions of methanol extract could be potential sources of new antimicrobial agents.
Zebrafish
hoxb1b is expressed during epiboly in the posterior neural plate, with its anterior boundary at the prospective r4 region providing a positional cue for hindbrain formation. A similar ...function and expression is known for
Hoxa1 in mice, suggesting a shared regulatory mechanism for hindbrain patterning in vertebrate embryos. To understand the evolution of the regulatory mechanisms of key genes in patterning of the central nervous system, we examined how
hoxb1b transcription is regulated in zebrafish embryos and compared the regulatory mechanisms between mammals and teleosts that have undergone an additional genome duplication. By promoter analysis, we found that the expression of the reporter gene recapitulated
hoxb1b expression when driven in transgenic embryos by a combination of the upstream 8.0-kb DNA and downstream 4.6-kb DNA. Furthermore, reporter expression expanded anteriorly when transgenic embryos were exposed to retinoic acid (RA) or LiCl, or injected with
fgf3/8 mRNA, implicating the flanking DNA examined here in the responsiveness of
hoxb1b to posteriorizing signals. We further identified at least two functional RA responsive elements in the downstream DNA that were shown to be major regulators of early
hoxb1b expression during gastrulation, while the upstream DNA, which harbors repetitive sequences with apparent similarity to the autoregulatory sequence of mouse
Hoxb1, contributed only to later
hoxb1b expression, during somitogenesis. Possible implications in vertebrate evolution are discussed based on these findings.
►The regulatory region of zebrafish
hoxb1b was defined by the reporter analysis. ►Zebrafish
hoxb1b regulation by caudalizing signals is mediated by the flanking DNA. ►Regulatory regions of
hoxb1b are conserved among different
Hox1 genes. ►Evolution of the regulatory mechanism of
hoxb1b can be explained by the DDC model.
Two peatland micro-relief forms (microforms) - hummocks and hollows - differ by their hydrological characteristics (water table level, i.e. oxic-anoxic conditions) and vegetation communities. We ...studied the CH4 and CO2 production potential and the localization of methanogenic pathways in both hummocks and hollows at depths of 15, 50, 100, 150 and 200 cm in a laboratory incubation experiment. For this purpose, we measured CH4 and CO2 production rates, peat elemental composition, as well as delta C-13 values of gases and solids; the specific inhibitor of methanogenesis BES (2-bromo-ethane sulfonate, 1 mM) was aimed to preferentially block the acetoclastic pathway. The cumulative CH4 production of all depths was almost one fold higher in hollows than in hummocks, with no differences in CO2. With depth, CO2 and CH4 production decreased, and the relative contribution of the hydrogenotrophic pathway of methanogenesis increased. The highest methanogenic activity among all depths and both microforms was measured at 15 cm of hollows (91%) at which the highest relative contribution of acetoclastic vs. hydrogenotrophic pathway (92 and 8%, respectively) was detected. For hummocks, the CH4 production was the highest at 50 cm (82%), where relative contribution of acetoclastic methanogenesis comprised 89%. The addition of 1 mM BES was not selective and inhibited both methanogenic pathways in the soil. Thus, BES was less efficient in partitioning the pathways compared with the delta C-13 signature. We conclude that the peat microforms - dry hummocks and wet hollows - play an important role for CH4 but not for CO2 production when the effects of living vegetation are excluded.
A cross sectional study was conducted to estimate the prevalence of Infectious Bursal Disease (IBD) and Newcastle Disease (ND) in poultry of Narsingdi district, Bangladesh. Post mortem of a total of ...208 dead birds were done for the diagnosis purpose. Different poultry species included in this study included broilers, layers, pigeon, duck etc. Among the examined birds, 38% were found to be affected with IBD, and 11% were affected with ND. Age of the birds for both IBD (19.95; 95%CI: 16-23) and ND (122.23; 95%CI: 98.62-145.83); and flock size only for IBD (1317; 95%CI: 1175-1460) was found significantly associated. The chicks aging between 16-23 days and flock size between 1175-1460 were found to be the most susceptible group to IBD, and adult poultry (98.62-145.83 days old) was mostly susceptible to ND. IBD and ND are highly prevalent in the study area. Therefore, it is necessary to conduct effective control measures to reduce the prevalence of these diseases. This study can help in designing appropriate control measures considering risk factors of these diseases.
The formation of microrelief forms in peatlands - elevated and dry hummocks, depressed wet hollows and intermediate lawns - is controlled by the interaction of water table, nutrient availability and ...dominant plant communities. This affects the composition and activity of various functional groups of microorganisms. With depth, the change in peat quality from less to more highly processed organic material additionally regulates microbial activity. We hypothesized that microbial biomass and enzyme activities are driven by aeration and by peat quality and therefore (i) they increase from hollows (water saturated/anaerobic) through lawns (intermediate) to hummocks (aerobic) in the top peat and ii) they decrease with depth due to increasing distance from fresh plant-derived inputs and lower oxygen availability. These hypotheses were tested for enzymes catalysing the decomposition of C-, N-, P- and S-containing organic compounds in peat of the three microform types at three depths (15, 50 and 200 cm). Microbial biomass and peat chemical characteristics were compared with enzyme kinetic parameters, i.e. maximal potential activity (Vmax) and the Michaelis constant (Km).
Microbial biomass carbon (MBC) and Vmax of β-glucosidase and N-acetyl glucosaminidase increased by 30–70% from hummocks and lawns to hollows in the top 15 cm, contradicting the hypothesis. Similarly, Km and the catalytic efficiency of enzymes (Ka = Vmax/Km) were best related to MBC distribution and not to the aeration gradient. With depth, Vmax of β-glucosidase, xylosidase and leucine aminopeptidase followed the hypothesized pattern in hollows. In contrast, MBC was 1.3–4 times higher at 50 cm, followed by successively lower contents at 15 and 200 cm in all microforms. The same depth pattern characterized the Vmax distribution of 6 out of 8 enzymes. Phosphatase activity decreased from drier hummock to wetter hollows and the higher activity throughout the peat profile suggested a high microbial demand for P. Enzyme activities and catalytic efficiency in peat were closely linked to the distribution of microbial biomass with depth, which in turn was best explained by P content. From the ecological perspective, these results clearly show that peat decomposition will be accelerated when microbial activity is stimulated e.g. by increased P availability.
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•Depth rather than microrelief controlled microbial biomass and enzyme activities distribution.•With depth, microbial biomass was 2–4 times higher at 50 followed by 15 and 200 cm.•Same pattern was for the activity distribution of 6 out of 8 enzymes with depth.•High phosphatase activity in the peat suggested a high microbial demand for P.•Microforms' aeration gradient was less important for microbial biomass and enzymes.
Cover crops are widely promoted in temperate regions of the northern hemisphere to replace or reduce fallow periods between cash crops. The reported benefits (improved ground cover, reduced nitrate ...leaching, increased soil organic matter among others) have prompted widespread interest in cover cropping in other agro-climatic zones, including Mediterranean environments such as southern Australia, where the wet, mild winters and hot dry summers are a stark contrast to temperate environments.
This review considers the reported benefits of cover crops in temperate environments in the context of cropping systems in the water-limited, Mediterranean climate in the grain-growing regions of southern Australia.
Published studies on cover cropping were critically assessed to evaluate whether the reported impacts may be relevant to Mediterranean-type climates.
Nitrate leaching is not generally problematic in southern Australian cropping systems due to low summer rainfall and high temperatures, and complete retention of crop stubbles can adequately protect the soil from erosion. Further, summer rainfall is low and sporadic which not only limits cover crop planting opportunities but means that water conserved over summer fallows contributes significantly to winter cash crop yield. Consequently, cover crop duration would need to be short (1–2 months) to balance the benefits of increased cover for water infiltration with transpiration loss during cover crop growth. Restricted cover crop biomass production due to water constraints and short fallow length will limit the potential value of the cover crop to increase soil organic matter, microbial activity, and biologically-fixed nitrogen contributions – all reported benefits for higher biomass cover crops in temperate environments. Appropriate tactical use of summer cover crops may arise in situations where (i) soil cover is reduced by winter crop failure or prolonged drought creating significant erosion risk, (ii) recalcitrant herbicide resistant weeds in winter crops require a chemical spring fallow and summer cover/forage crop, which could be grazed, (iii) full soil profiles at harvest and wet seasonal outlook provide opportunities for cover crop growth without significant pre-emptive competition, and (iv) sandy soil profiles with low water holding capacity combined with reliable winter rainfall minimise contributions of summer rainfall to winter crop yields. The value of more diverse cover crop species to soil health in cereal-brassica or cereal-brassica-legume cash crop rotations is not known.
The rationale for widespread summer cover crop use in southern Australia is currently not compelling without more evidence for the scale and mechanisms of the anticipated benefits.
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•Evidence for benefits of cover crops in Mediterranean-type climates is lacking.•Opportunities to sow cover crops over the hot dry summer period are limited.•Cover crop water use may reduce yields of subsequent cash crops.•Tactical use of summer cover crops in targeted situations may be warranted.
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•Elevated CO2 reduced soil water use during early growth stages resulting in improved yield and N2 fixation under drought.•Elevated CO2 depleted seed N concentration under drought, ...and was associated with decreased N2 fixation during later growth stages.•Neither soil N uptake nor remobilization to the grain was affected by elevated CO2.•We propose a conceptual model indicating the crucial role of prolonging N2-fixation through the critical pod-filling phase to maintain seed N under elevated CO2.
Legumes grown in Mediterranean environments frequently experience terminal drought which reduces yield and N2 fixation processes. Decreased N2 fixation during reproductive phases may constrain seed nitrogen concentrations (N), reducing protein concentration of grain legumes. Plants grown under elevated atmospheric CO2 concentrations (CO2) have greater water use efficiency. This may result in reduced use of conserved/stored soil water, potentially helping to reduce soil water deficits later during grain filling. The extent that this process applies to drought sensitive grain legumes, which are extensively cultivated in Mediterranean environments is unclear. The objectives of this study were to investigate yield, N2 fixation and seed N response of faba bean (Vicia faba L. cv. ‘Fiesta’) grown in a dryland Mediterranean-type environment under elevated CO2. Plants were grown in soil columns under ambient CO2 (˜400 ppm) or elevated CO2 (eCO2, ˜550 ppm) in a Free-Air CO2 Enrichment (FACE) facility in the field. One sub-group was continuously well-watered (80% field capacity, FC), whereas a second sub-group was exposed to a drought treatment (water was withheld until 30% FC was reached, which was then maintained during the reproductive phases). Biomass, gas exchange, 13C isotopic discrimination, N2 fixation by the natural abundance 15N method, nodulation and soil water content were assessed throughout the crop developmental stages.
Initially, plants grown under elevated CO2 depleted soil water more slowly in the drought treatment than those under ambient CO2, but as plants grown under elevated CO2 produced more biomass they used soil water more rapidly, especially towards the critical pod-filling phase. Water savings during the first phase of the drought treatment, through flowering up to the start of pod-filling, were associated with increased yield (+25%) and N2 fixation (+15%) under drought. Elevated CO2-induced stimulation of nodulation and nodule density helped maintain N2 fixation under drought, even though nodule activity decreased under the combined effect of eCO2 and drought from pod-filling onwards. This later stage decrease was associated with decreased carbohydrate and increased amino acid concentrations in nodules, indicating a down-regulation of N2 fixation. Associated with the decrease of N2 fixation during pod-filling, seed N concentration was lower under the combination of eCO2 and drought. We propose a conceptual model to explain the importance of N2 fixation during the grain filling stage to maintain seed N concentration under eCO2. These findings suggest that eCO2-induced savings in soil water may mitigate negative effects of drought on yield and N2 fixation of faba bean, without fully compensating the effect of prolonged drought on seed N concentration.
Background and aims
Alkaline dispersive subsoils are characterised by multiple physicochemical constraints that limit plant water and nutrient acquisition. Subsoil amelioration through organic ...amendments (OAs) requires significant financial investment. Whereas large yield responses can result following amelioration, sometimes small or even negative yield responses can occur, resulting in a significant net financial loss for the farmer. For farmers to feel confident in investing in subsoil amelioration better prediction of the likely yield improvement is required and to achieve this an understanding of the underlying mechanisms such as nutritional and non-nutritional drivers, and the longevity of benefits are required. Our study aimed to ascertain the drivers of yield improvements from subsoil amelioration with OAs.
Methods
In a controlled environment, wheat (
Triticum aestivum
L. cv. Scepter) plants were grown until maturity in a Solonetz amended with (i) poultry litter (PL; 20 t ha
−1
), and (ii) NPKS nutrients and (iii) model organic carbon (MOC) with equivalent amounts of nutrients and total carbon contained in the PL, and (iv) NPKS + MOC. Control (no amendments) and gypsum (5 t ha
−1
) were included as district practices. Before planting, amendments were applied as a vertical band at 20 – 40 cm depth and pre-incubated. Plant biomass, grain yield, root biomass, and physicochemical properties of the soil associated with the amendment band were quantified at harvest.
Results
Compared to the control, wheat grain yield was increased by 30% for PL, 43% for NPKS + MOC, and 61% for NPKS, but no differences in yield were detected for MOC or gypsum. The lower yield increase by PL than NPKS with or without MOC was likely due to the readily available form of plant nutrients in the inorganic fertilisers vs slower mineralisation of nutrients from the OAs. Improvement in soil physicochemical properties following amelioration of alkaline dispersive subsoil resulted in better root proliferation and subsoil water use. Grain yield showed a positive correlation with root biomass in the subsoil layers.
Conclusions
In the short-term (one crop cycle), organic amendments improved soil’s non-nutritional physical and chemical properties but had no additional nutritional effect on wheat grain yield compared to inorganic fertiliser application. Longer-term studies are needed to determine the legacy effect of the nutritional contribution in conjunction with the improvement of soil structure from the OAs in alkaline dispersive subsoils.
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