Gut melatonin response to microbial infection in carp <Emphasis Type="Italic">Catla catla</Emphasis>

The purpose of present study was to demonstrate the response of gut melatoninergic system to Aeromonas hydrophila infection for 3 or 6 days and search for its correlation with the activity of different antioxidative and digestive enzymes to focus their interplay under pathophysiological conditions in carp (Catla catla). Microscopic study of gut in infected fish revealed degenerative changes in the tunica mucosa and lamina propria layers with sloughed off epithelial cells in the lumen. The activity of each digestive enzyme was reduced, but the levels of melatonin, arylalkylamine-N-acetyl transferase protein, the key regulator of melatonin biosynthesis, and different enzymatic antioxidants in gut were gradually and significantly increased with the progress of infection. Gut melatonin concentrations in A. hydrophila challenged carp by showing a positive correlation with the activity of each antioxidative enzyme, and a negative correlation with different digestive enzymes argued in favor of their functional relation, at least, during pathological stress. Moreover, parallel changes in the gut and serum melatonin titers indicated possible contribution of gut to circulating melatonin. Collectively, present carp study provided the first data to suggest that endogenous gut melatonin may be implicated to the mechanism of response to microbial infections in any fish species.     

Microtopography as a factor in the degradation of Vertisols in central India

Earlier studies on soil degradation in Vertisols of the Purna Valley of central India indicated that the semiarid climate characterized by a mean annual rainfall (MAR) of 875 mm and a tropustic moisture regime is responsible for the development of calcareous sodic soils. Recent observations, however, indicate that in the adjacent east upland of the Purna Valley, namely in the Pedhi Watershed, Vertisols have drainage problems, although the area receives a higher MAR than the Purna Valley, the total MAR being 975 mm. The Pedhi Watershed covers an area of 44 321 ha, and is characterized by a tropustic moisture regime and a hyperthermic temperature regime. Vertisols of the Pedhi Watershed are deep, calcareous, clayey and very dark greyish‐brown to dark yellowish‐brown in colour. Vertisols occur on both microhigh (MH) and microlow (ML) positions. The distance between the MH and ML positions is approximately 6 km and the elevation difference is 0.5–5 m. Cracks > 1 cm wide extend down to the slickenside zones in soils of ML whereas they cut these zones in some soils in MH positions. The soils of the MH positions are strongly alkaline and those of ML are mildly alkaline. The present study attempts to relate the distinctly different morphological and chemical properties of Vertisols in the MH and ML positions to pinpoint the prime factor responsible for the impairment of drainage on the basis of physical, chemical, mineralogical and micromorphological data. These data were obtained from 13 Vertisol pedons of methodically selected sites in the Pedhi Watershed. Despite their similar coefficient of linear extensibility (COLE), volumetric shrinkage potential (VSP), clay contents and amounts of fine smectite clay, the plasmic fabric of the slickenside horizons in soils of ML is porostriated, whereas in soils of MH it is stipple speckled to mosaic speckled, indicating weak plasma separation. The soils have both pedogenic and non‐pedogenic calcium carbonates (CaCO₃). The semiarid climate induces the precipitation of CaCO₃ with a concomitant development of subsoil sodicity. The degree of development of sodicity (Exchangeable sodium percentage (ESP) ≥ 5) is more in soils of MH as evidenced by the higher amount of pedogenic CaCO₃ (PC). The lack of water in soils of MH position is the reason for weak swelling of smectite, for larger amounts of PC, for higher alkalinity and sodicity, and for cracks cutting through the slickenside zones. Formation of sodic Vertisols in MH alongside non‐sodic Vertisols in ML positions is a unique phenomenon. It develops because of microtopographic differences which modify distribution of water across the landscape and facilitate greater penetration of rainwater in ML positions. The development of sodicity due to microtopographic differences assumes a great importance when a future land resource management programme on Vertisols in the higher MAR zone of overall a semiarid climate is considered. Copyright © 2002 John Wiley & Sons, Ltd.     

Robust genetic transformation of sorghum (<Emphasis Type="Italic">Sorghum bicolor</Emphasis> L.) using differentiating embryogenic callus induced from immature embryos

Background

Sorghum (Sorghum bicolor L.) is one of the world’s most important cereal crops grown for multiple applications and has been identified as a potential biofuel crop. Despite several decades of study, sorghum has been widely considered as a recalcitrant major crop for transformation due to accumulation of phenolic compounds, lack of model genotypes, low regeneration frequency and loss of regeneration potential through sub-cultures. Among different explants used for genetic transformation of sorghum, immature embryos are ideal over other explants. However, the continuous supply of quality immature embryos for transformation is labour intensive and expensive. In addition, transformation efficiencies are also influenced by environmental conditions (light and temperature). Despite these challenges, immature embryos remain the predominant choice because of their success rate and also due to non-availability of other dependable explants without compromising the transformation efficiency.

Results

We report here a robust genetic transformation method for sorghum (Tx430) using differentiating embryogenic calli (DEC) with nodular structures induced from immature embryos and maintained for more than a year without losing regeneration potential on modified MS media. The addition of lipoic acid (LA) to callus induction media along with optimized growth regulators increased callus induction frequency from 61.3 ± 3.2 to 79 ± 6.5% from immature embryos (1.5–2.0 mm in length) isolated 12–15 days after pollination. Similarly, the regeneration efficiency and the number of shoots from DEC tissue was enhanced by LA. The optimized regeneration system in combination with particle bombardment resulted in an average transformation efficiency (TE) of 27.2 or 46.6% based on the selection strategy, 25% to twofold higher TE than published reports in Tx430. Up to 100% putative transgenic shoots were positive for npt-II by PCR and 48% of events had < 3 copies of transgenes as determined by digital droplet PCR. Reproducibility of this method was demonstrated by generating ~ 800 transgenic plants using 10 different gene constructs.

Conclusions

This protocol demonstrates significant improvements in both efficiency and ease of use over existing sorghum transformation methods using PDS, also enables quick hypothesis testing in the production of various high value products in sorghum.

     

Effects of contrasting biochars on the leaching of inorganic nitrogen from soil

Journal of Soils and Sediments - The use of excessive nitrogen (N) fertilizers usually causes soil N leaching, eutrophication, and water pollution. Nevertheless, biochars may play an important role...     

Experimental verification of two calculation methods for relating horizontal infiltration to soil-water diffusivity

Two recently proposed methods are used to relate horizontal infiltration data to soil- moisture diffusivity. The theoretical background is only discussed briefly and more emphasis is given to an experimental verification. With the described methods numerous experiments were performed on two soils under varying initial moisture content in the same soil samples. Data of four representative experiments are summarized in a table and a number of figures.The horizontal infiltration into a silty loam soil with an initial moisture content of 0.08 cm³/cm³ is not in accordance with theoretical expectations, whereas that into a fine sand with the same initial moisture content is in accordance with theory. The latter may be due to the building up of a soil-air pressure in the silty loam which was recorded to be in the order of 40 mbar.It further appears that the approximate method of the two referred to above yields similar results in terms of D(θ) as compared with the exact but more laborious method only if the soil was air dry.Finally two examples of (re)-using the obtained D(θ) data are given.     

Influence of dietary phosphorus on mineralization and morphology of Indian major carp,catla (<Emphasis Type="Italic">Catla catla</Emphasis>) fingerlings

The present study was conducted to investigate the changes in mineralization and morphology in response to graded levels of dietary phosphorus in Indian major carp, Catla (Catla catla) fingerlings (av. wt. 4.23 ± 0.87 g). The experimental system constituted of 24 150-L capacity plastic tanks (eight treatments, three replicates) stocked with 20 fingerlings each. Eight isonitrogenous and isocaloric semi-purified diets (crude protein 35%, crude lipid 8.5%) were formulated with graded levels of phosphorus (0%-control; 0.1; 0.3; 0.5; 0.7; 0.9; 1.1; 1.3; 1.5%) using KH₂PO₄. The fish were fed twice daily with the respective feeds for a period of 120 days. The percentage of ash content in whole body, vertebrae and opercular bones was found to be significantly (P < 0.05) lower in fish fed low levels of dietary phosphorus (T₁, T₂) in comparison with other treatments. The concentration of phosphorus and calcium was found to be significantly (P < 0.05) lower in whole body, vertebrae and opercula of fish fed low phosphorus diets (T₁, T₂) relative to treatments with higher levels of dietary phosphorus supplementation. The concentration of magnesium in opercular and vertebral tissues of T₁ group was significantly (P < 0.05) lower than all other groups. The X-ray radiographs did not reveal any skeletal deformities in any of the treatments. Truss analysis showed absence of significant morphological variations between fish of different treatments. The deficiency of dietary phosphorus in catla led to significantly lower mineralization of whole body and bone tissues, but the deficiency was not severe enough to cause skeletal deformities and morphological changes in the fish.     

The Effects of Timing of an Interim Harvest on the Yield and Composition of Lablab purpureus

Lablab purpureus was grown in two field experiments in consecutive years to evaluate the effects of the timing of an interim harvest on the yield and nutritive value of the harvested material and the subsequent regrowth, which was determined from the second and final harvest. Delaying the first harvest to 50–70 days post-sowing increased the total (first plus second harvests) dry matter (DM) yield, with a greater first harvest and reduced second harvest DM yield. The delay also reduced the crude protein concentration of the first harvest and tended to increase its modified acid-detergent (MAD) fibre concentrations. The delay increased the crude protein concentration and decreased the MAD fibre concentration of the second harvest. The total crude protein yield of both harvests increased with late interim harvesting. The first harvest plant calcium concentration increased and phosphorus concentration decreased with a delay in the interim harvest. It is concluded that, in the difficult growing conditions of the Sahelian zone of sub-Saharan Africa, delaying the interim harvest of Lablab purpureus until 50–70 days post-sowing will have beneficial effects on total dry matter and crude protein yields.     

Endogenous gibberellins of mango shoot-tips and their significance in flowering

Eight gibberellin-like substances were isolated from mango shoot-tips. Factors X₂, X₃, X₄, X₅₍₂₎, X₆₍₁₎, X₇ and X₈ were tentatively identified as gibberellins A₁, A₇, A₉, A₄, A₃, A₅ and A₆, respectively, on the basis of their behaviour in column, paper and thin-layer chromatography. Factor X₁ could not be identified.The endogenous level of gibberellins X₁, X₂, X₃, X₄, X₅ and X₆ was higher in “off” year shoot-tips than in “on” year shoot-tips. This suggests that the failure of flowering in an “off” year may be accompanied by a higher level of gibberellins in the shoot-tips.     

Isolation of saprophytic Cryptococcus neoformans

Isolation of Cryptococcus neoformans was carried out on sunflower seed agar medium (SFA) and Sabouraud dextrose agar (SDA). Out of 346 environmental substrates (133 fruits, 107 avian extreta, 91 vegetables and 15 wooden scrapings) tested, 3 specimens were positive for C. neoformans. The positive isolations came from the fruits of 2 banana (Musa sapientum) and a potato tuber (Solnum tuberosum). The pathogen could not be demonstrated in 107 samples of avian droppings and 15 of wooden materials. All the 3 isolates of the yeast were obtained on SFA, while they were not cultured on the plates of SDA with chloramphenicol which were badly contaminated with rapidly growing molds, yeasts and bacteria. To the present author's knowledge, this appears to be the first reports of the isolation of this pathogenic basidiomycetous yeast from contaminated fruits of banana. We suggest more comprehensive ecological surveys to search for environmental niche of C. neoformans var. neoformans and C. neoformans var. gattii as the latter variety is also implicated in the etiology of cryptococcosis.