Effect of salinity and inoculation on growth,nitrogen fixation and nutrient uptake ofVigna radiata (L.) Wilczek

This study reports the effect of salinity and inoculation on growth, ion uptake and nitrogen fixation byVigna radiata. A soil EC_e level of 7.5 dS m⁻¹ was quite detrimental causing about 60% decline in dry matter and grain yield of mungbean plants whereas a soil EC_e level of 10.0 dS m⁻¹ was almost toxic. In contrast most of the studied strains of Rhizobium were salt tolerant. Nevertheless, nodulation, nitrogen fixation and total nitrogen concentration in the plant was drastically affected at high salt concentration. A noticeable decline in acetylene reduction activity occurred when salinity level increased to 7.5 dS m⁻¹.     

Morphology,physiology and infectivity of twoFrankia isolates An 1 and An 2 from root nodules ofAlnus nitida

Summary Two different strains, An 1 and An 2, were obtained from root nodules ofAlnus nitida Endl., collected from one locality in the area of its natural habitat near Bahrin, District Swat, Pakistan. The light and electron microscopy of the isolates revealed the occurrence of septate and branched hyphae bearing sporangia and vesicles. The strains differed in their growth requirements, nitrogen-fixing ability and production of extracellular pigments, thus indicating the existence of more than oneFrankia strain in the same locality. In the absence of combined nitrogen in the medium strain An 1 formed vesicles and fixed N₂ (up to 200 nmol C₂H₄. mg protein^–1.h^–1), while strain An 2 under the experimental conditions formed only few vesicles and fixed N₂ at a very low rate (ca 10 nmol C₂H₄. mg protein^–1 .h^–1). The nitrogenase activity of strain An 1 was strongly affected by the O₂ concentration.Frankia An 1 and An 2 were infective and effective onA. nitida andA. glutinosa but not onDatisca cannabina andElaeagnus umbellata. Both An 1 and An 2 strains were more infective and effective onA. glutinosa thanFrankia strains AvcIl and CpI1.     

Enhancing crop growth, nutrients availability, economics and beneficial rhizosphere microflora through organic and biofertilizers

Field experiment was conducted on fodder maize to explore the potential of integrated use of chemical, organic and biofertilizers for improving maize growth, beneficial microflora in the rhizosphere and the economic returns. The treatments were designed to make comparison of NPK fertilizer with different combinations of half dose of NP with organic and biofertilizers viz. biological potassium fertilizer (BPF), Biopower, effective microorganisms (EM) and green force compost (GFC). Data reflected maximum crop growth in terms of plant height, leaf area and fresh biomass with the treatment of full NPK; and it was followed by BPF+full NP. The highest uptake of NPK nutrients by crop was recorded as: N under half NP+Biopower; P in BPF+full NP; and K from full NPK. The rhizosphere microflora enumeration revealed that Biopower+EM applied along with half dose of GFC soil conditioner (SC) or NP fertilizer gave the highest count of N-fixing bacteria (Azotobacter, Azospirillum, Azoarcus andZoogloea). Regarding the P-solubilizing bacteria,Bacillus was having maximum population with Biopower+BPF+half NP, andPseudomonas under Biopower+EM+half NP treatment. It was concluded that integration of half dose of NP fertilizer with Biopower+BPF / EM can give similar crop yield as with full rate of NP fertilizer; and through reduced use of fertilizers the production cost is minimized and the net return maximized. However, the integration of half dose of NP fertilizer with biofertilizers and compost did not give maize fodder growth and yield comparable to that from full dose of NPK fertilizers.     

Prediction Factors of Recurrent Ischemic Events in One Year after Minor Stroke

Background

The risk of a subsequent stroke following a minor stroke is high. However, there are no effective rating scales to predict recurrent stroke following a minor one. Therefore, we assessed the risk factors associated with recurrent ischemic stroke or transient ischemic attack (TIA) within one year of minor stroke onset in order to identify possible risk factors.

Methods

Eight hundred and sixty-three non-cardioembolic ischemic stroke patients in the Chinese IntraCranial AtheroSclerosis Study that presented with minor stroke, defined as an admission National Institutes of Health stroke scale (NIHSS) score of ≤3, were consecutively enrolled in our study. Clinical information and imaging features upon admission, and any recurrent ischemic stroke or TIA within one year was recorded. Cox regression was used to identify risk factors associated with recurrent ischemic stroke or TIA within the year following stroke onset.

Results

A total of 50 patients (6.1%) experienced recurrent ischemic stroke or TIA within one year of minor stroke onset. Multivariate Cox regression model identified lower admission NIHSS score (HR, 1.75; 95% CI, 1.32 to 2.33; P<0.0001), history of coronary heart disease (HR, 2.62; 95% CI, 1.17 to 5.86; P = 0.02), severe stenosis or occlusion of large cerebral artery (HR, 4.68; 95% CI, 1.87 to 11.7; P = 0.001), and multiple acute cerebral infarcts (HR, 2.61; 95% CI, 1.01 to 6.80; P = 0.05) as independent risk factors for recurrent ischemic stroke or TIA within one year.

Conclusions

Some minor stroke patients are at higher risk for recurrent ischemic stroke or TIA. Urgent and intensified therapy may be reasonable in these patients.     

Optimization of redox reactions employing whole cell biocatalysis

The ability of Saccharomyces cerevisiae to catalyse the reduction reaction of carboxylic acids into alcohols is described. Earlier reports have led to the characterization of the reduction of carbonyl groups into alcohols mediated by the enzyme alcohol dehydrogenase. We investigated the ability of this organism to catalyse the said conversion using the carboxylic acids, acetic acid and butyric acid. In the absence of any previous characterization, whole cell catalysis proved effective. The uptake of these acids from the medium was estimated using a plate assay method involving litmus-agar. The plate assay was found to be a convenient and extremely adaptable method for quantitation of acids in organic as well as aqueous medium. The comparison of existing paradigms in pure protein catalysis with whole cells catalysis proved anomalous. We report that it is solvent toxicity rather than hydrophobic index that correlates with the activity observed in non-aqueous conditions for whole cell biocatalysis. Reduction of acetic acid as well as butyric acid occurred, with efficiency of reaction with butyric acid being marginally higher. The reduction therefore occurs for both the short chain carboxylic acids used in this study. We therefore illustrate the reduction route of acids into alcohols and propose a model two-step pathway for the reaction. Process optimization may be further attempted to enhance the presently moderate reaction efficiencies. Steps made in the direction by studying the pH dependency and use of sacrificial substrate have yielded encouraging results.     

Plasma thyroxine and cortisol profiles and gill and kidney Na+/K+-ATPase and SDH activities during acclimation of the catfish Heteropneustes fossilis (bloch) to higher salinity, with special reference to the effects of exogenous cortisol on hypo-osmoregulatory ability of the catfish

When the stenohaline catfish Heteropneustes fossilis was transferred from fresh water (FW) to 30% seawater (SW), the Na(+)/K(+)-ATPase activity significantly increased in the kidney, while in gills it remained more or less constant. A reverse pattern was observed for succinic dehydrogenase (SDH) activity inasmuch as it significantly increased in gills and remained unchanged in the kidney. Plasma osmolality significantly increased within 3 days of transfer to 30% SW and remained significantly higher throughout the duration of experiment. These results suggest that catfish gills may not be able to reverse their function from salt uptake in FW to salt excretion at higher salinity, and that the elimination of monovalent as well as divalent ions is performed by the kidney but not the gills. The significant decline in plasma cortisol (F) levels following transfer to higher salinity may not be due to reduced production but rather to an enhanced utilization and clearance rate, a conclusion supported by the fact that exogenous administration of cortisol acetate (FA) resulted in significant increases in branchial and renal Na(+)/K(+)-ATPase in FW and 30% SW. FA also improved the plasma osmotic regulatory ability of the catfish, possibly due to a change in branchial function from salt-absorption to salt excretion, as was evident from a significant increase in branchial Na(+)/K(+)-ATPase activity in the fish in 30% SW pretreated with FA for 5 days. Consistently higher levels of plasma thyroxine (T4) following transfer to higher salinity suggest the involvement of this hormone at higher salinity.     

Actinomycetous root nodules in angiosperms of Pakistan

Summary In a survey, out of the nineteen genera of non-leguminous angiosperms that are already reported to bear actinomycete-induced nitrogen-fixing root nodules from various parts of the world, the species of seven genera (Alnus, Elaeagnus, Hippophaë, Coriaria, Datisca, Rubus and Casuarina) have been located in Pakistan and checked for nodulation. All the investigated species of the these genera, except those of Rubus and some of the introduced species of Casuarina, were found to bear nodules. In all 12 species belonging to six genera of five families have been recorded to bear actinorhizal nodules in Pakistan.     

Observations on the ultrastructure ofFrankia sp. in root nodules ofDatisca cannabina L.

Summary The fine structures of the microsymbiont inside the root nodules ofDatisca cannabina have been studied by light, by transmission- and by scanning-electron microscopy. The endophyte is prokaryotic and actinomycetal in nature. The hyphae are septate and branched, diameter 0.3–0.5 m. The tips of hyphae are swollen to form electron-dense, clubshaped to filamentous vesicles, ranging in diameter: 0.4–1.4 m. The endophyte penetrates through walls of the cortial cells. The infected zone is kidney shaped and confined to one side of the acentric stele. The orientation of infection is reversed from other actinorhizae exceptCoriaria. The hyphae are near the host cell wall and vesicles are directed towards the central vacuole. Vesicles are aseptate and no collapsing of the vesicle cell wall (void area) has been observed. Vesicle clusters structures are globular with an opening at one side of the cluster. The host cell is multinucleate or contains a lobed nucleus. Groups of mitochondria are located in between the hyphae, suggesting a strong association between the host and the endophyte for energy supply and amino acid production. The consequences of the inability to separate the mitochondria from the vesicle clusters in nodule homogenates in physiological studies have been discussed.Isolated vesicles clusters showed dehydrogenase activity, indicated by the presence of formazan crystals, after incubation with NADH and NBT. Strongest reducing activity was found within the vesicles. The possible role of filamentous vesicles in nitrogen fixation has been discussed.     

Arsenic accumulation in Ocimum spp. and its effect on growth and oil constituents

A comparative evaluation of As accumulation and subsequent effects upon exposure to arsenite [As(III)] was performed in three species of Ocimum. Plants accumulated high amount of As (μg g^?1 dry weight; dw) (662 in O. tenuiflorum, 764 in O. basilicum and 831 in O. gratissimum at 100 μM As(III) after 10 days) with the order of accumulation being roots > stem > leaves. A significant reduction in plant height and biomass was observed. However, essential oil yield and major oil constituents, such as eugenol, methyl chevicol, and linalool, increased at lower As(III) concentrations [mostly up to 25 μM As(III)] in all three species. Positively, no detectable amount of As was found in oil of any species. The study proposes that Ocimum may be used as a phytoremediator and at the same time as a source of essential oils under proper regulation.