Modulation of Na+ transport across isolated rumen epithelium by short-chain fatty acids in hay- and concentrate-fed sheep

The effect of increasing concentrations of short-chain fatty acids [SCFA; mixture of the Na+ salts of acetic acid (62.5%), propionic acid (25.0%) and of butyric acid (12.5%)] on Na+ transport of sheep rumen epithelium was studied in vitro. The conventional Ussing chamber method was used for measuring Na+ transport rates (22Na+), short-circuit current (Isc) and tissue conductance (GT) of isolated rumen epithelium. SCFA in the buffer solution on the mucosal side caused a linear increase of Jnet Na+ from 1.14, to 1.22, 1.78 and 2.50 microeq/cm2/h in hay-fed sheep at 0, 15, 40 and 80 mmol/l SCFA, respectively. In a second study, the effect of higher SCFA concentrations [0 (control), 80, 100 and 120 mmol/l] was investigated with epithelia from two groups of sheep. One group was subjected to hay ad libitum, whereas the other received concentrate feed (800 g/day in equal portions at 7.00 am and 3.00 pm) and hay ad libitum. Epithelia from concentrate-fed sheep again showed a significant (p < 0.05) and linear increase in Jnet Na+ at 80, 100 and 120 mmol/l. However, in hay-fed sheep, the difference in increase among 80, 100 and 120 mmol/l SCFA was not significant, indicating that, above 80 mmol/l SCFA Jms and Jnet exhibit saturation. Moreover, Na+ fluxes (Jms and Jnet) were generally higher in concentrate-fed than in hay-fed sheep at all SCFA concentrations and significant differences were observed at 100 and 120 mmol/l SCFA. The obtained results confirm the effect of SCFA on Na+ transport and are in agreement with studies regarding feeding regimes and electrolyte transport in the rumen. The important new observation is the increase of Na+ transport in concentrate-fed sheep even at high concentrations of SCFA (100 and 120 mmol/l). The enhanced activity of the Na+/H+ exchanger at these SCFA concentrations supports the assumption that the capacity for regulating the intracellular pH by extrusion of protons is increased, suggesting an adaptation in concentrate-fed sheep. This adaptation could prevent possible disturbances of epithelial functions (transport and barrier) under conditions of increased SCFA absorption.     

Toxicological effects and recovery of the corneal epithelium in Cyprinus carpio communis Linn. exposed to monocrotophos: an scanning electron microscope study

This study was conducted based on the evidence of fish habitats in North India being affected by organophosphate pesticides draining from agricultural fields into bodies of water, especially during the rainy season. Various tissues of fish such as scales, gills ovaries, kidney, and liver have been studied from the toxicological point of view, but the toxicological effects of aquatic pollutants on fish cornea have not been investigated to date. We conducted comparative toxicological studies on the cornea of Cyprinus carpio communis using two sublethal (0.038 and 0.126 ppm) concentrations of monocrotophos pesticide for 30 days. Corneas from all the groups were evaluated by a scanning electron microscope. The fish exposed to the monocrotophos pesticide developed corneal necrosis due to the formation of crystalloid‐like structures, thinning and shrinkage of microridges on the corneal epithelium. After 30 days, fish from the monocrotophos‐treated tank were transferred to normal environmental conditions. After 60 days under natural condition, epithelial cells did not fully recover. In conclusion, exposure to monocrotophos induces irreversible changes in the cornea of C. carpio communis. As fish and mammalian visual systems share many similarities, the reported finding may offer useful insights for further toxicological and ophthalmological studies in humans.     

Meltblown nanofiber media for enhanced quality factor

Nanofibers definitely hold great advantage and promise in filtration as they have very high specific surface area, which ensures greater probability of capturing the particles and hence, the filtration efficiency of the nanofiber filter media is high. Electrospun nanofibers are prohibitively expensive due to extremely low production rate. With recent advances in melt blowing technology, nanofibers could be produced at production rate few orders of magnitude higher than that of conventional single syringe electrospinning and hence, quite cost effective. Influence of air pressure and die to collector distance (DCD) were studied on the number average fiber diameter for the nanofibers as well as the performance properties of the nonwoven webs, each factor at three discrete levels. The nanofibers were as fine as 260 nm. A very encouraging observation of the study is very high values of quality factor observed for nanofiber nonwoven filter media. In order to compare the filtration efficiency of different nanofiber nonwoven media samples with different basis weight, a novel term of specific filtration efficiency is proposed and was found that the specific filtration efficiency with the increase in DCD or air pressure.     

Genetic diversity analysis in date palm (Phoenix dactylifera L.): a comparative assessment using ISSR and RAPD marker assays

SUMMARY

A comparative study was conducted to evaluate genetic diversity in 45 genotypes of date palm (Phoenix dactylifera L.), including both male and female plants, employing RAPD and ISSR marker systems. The data were analysed to calculate the total number of bands, the number of polymorphic bands, the percentage polymorphism, the average number of bands per primer, the effective multiplex ratio (EMR), the polymorphic information content (PIC), the marker index (MI), and genetic similarity coefficients. The 37 RAPD and 53 ISSR primers used generated 363 and 608 scorable amplified products, respectively, of which 95.0% and 90.9% were polymorphic. The ISSR markers produced more information than the RAPD markers due to their higher EMR and MI values. Jaccard similarity values among male plants, female plants, and between all male and all female plants varied between 0.72 – 0.80. The results indicate the effectiveness of these two marker systems for demonstrating genetic relationships among date palm genotypes.     

The effect of short chain fatty acids on calcium flux rates across isolated rumen epithelium of hay-fed and concentrate-fed sheep

The present in vitro experiment was conducted to study the effect of two concentrations of short chain fatty acids [SCFA: 0 (control), 40 and 100 mmol/l in the buffer solution on mucosal side] on calcium ion (Ca2+) transport across the isolated rumen epithelium of two groups of sheep. One group was subjected to hay ad libitum, whereas the other to concentrate feed (800 g per day in equal portion at 7.00 and 15.00 hours and hay ad lib). The conventional Ussing chamber method was used for measuring the Ca2+ transport rates (45Ca), short-circuit current (Isc) and tissue conductance (GT) of isolated rumen epithelium. The SCFA significantly increased Isc of the epithelia of concentrate-fed sheep. In both hay- and concentrate-fed animals, 45Ca flux rates showed an almost linear increase in net flux rate () with rising concentrations of SCFA, as a result of a combined effect of a large increase in mucosal-to-serosal flux rates () and an almost linear, but small, decrease in serosal-to-mucosal flux rate (). In concentrate-fed sheep and were significantly higher in tissues incubated with SCFA compared with hay-fed animals. The well-known adaptable morphological and functional changes in the rumen epithelium attributable to concentrate feeding obviously include Ca2+ transport; such feeding therefore may be considered as a possible prophylactic measure in the prevention of milk fever.     

Puddling, irrigation, and transplanting-time effects on productivity of rice–wheat system on a sandy loam soil of Punjab, India

Rice–wheat productivity in irrigated tract of the Indo-Gangetic plains is constrained by water and energy limitations. In order to minimize unproductive soil water evaporation and percolation loss at a field scale, management practices include soil puddling, water-economizing irrigation schedule, and matching growth cycle with periods of low evaporative demand. This 3-year field study examines combined effects of these options on rice–wheat productivity and water-use efficiency (WUE) and energy-use efficiency (EUE) on a sandy loam soil in an irrigated semi-arid sub-tropical environment. Treatments included combinations of three puddling intensities, viz., one (P₁), two (P₂), and four (P₄) runs of a tine cultivator in ponded water after a common pre-puddling tillage; with two irrigation regimes, viz., continuous submergence (I₁) throughout the growing season, and intermittent submergence (I₂) with continuous submergence for 2 weeks after transplanting followed by 2-day interval between successive irrigations, and two transplanting dates, viz., first fortnight of June (D₁) and end June (D₂) to impose variation in seasonal evaporative demand. Residual effect of puddling in rice on succeeding wheat was also evaluated during the 3 years.

Intensive puddling and water-economizing schedule caused a significant reduction in seasonal percolation loss primarily due to puddling-induced changes in soil bulk density and hydraulic behavior. Increasing puddling intensity from P₁ to P₂ enhanced mean rice yield by 0.2–0.3 Mg ha⁻¹, but additional puddling did not improve yield significantly. Mean grain yield increase with I₁ over I₂ ranged between 0.3 and 0.6 Mg ha⁻¹. Interaction effect between puddling and irrigation indicate that yield benefit with I₁ over I₂ was greatest in P₁ regime (0.6 Mg ha⁻¹), and the effect decreased with increase in puddling intensity. Delayed transplanting caused a decline of 0.3–0.5 Mg ha⁻¹ in rice yield. Although maximum yield was realized with combination of P₂ or P₄ regime with I₁ regime, but water-use efficiency was greater with I₂ compared to I₁ regime by 1.1 kg ha⁻¹ mm⁻¹ in 2000 and by 0.3 kg ha⁻¹ mm⁻¹ in 2001. It indicates that yield gain with additional irrigation were not commensurate with additional water input. Energy analysis also showed that energy-use efficiency was 6.8, 7.2, and 6.6 kg kWh⁻¹ for P₁, P₂, and P₄ regimes suggesting that yield gain with P₄ did not match energy input for additional puddling. Further, there was a greater risk of yield reduction of succeeding wheat with P₄ (by 0.2–0.3 Mg ha⁻¹) compared to P₁ or P₂ regime.