Canine periodontal disease control using a clindamycin hydrochloride gel

Stabilizing or reducing periodontal pocket depth can have a positive influence on the retention of teeth in dogs. A topical 2% clindamycin hydrochloride gel (CHgel) was evaluated for the treatment of periodontal disease in dogs. The CHgel formulation provides for the sustained erosion of the matrix, but also flows into the periodontal pocket as a viscous liquid, and then rapidly forms a gel that has mucoadhesive properties and also may function as a physical barrier to the introduction of bacteria. A professional teeth cleaning procedure including scaling and root planing was done in dogs with one group receiving CHgel following treatment. Periodontal health was determined before and after the procedure including measurement of periodontal pocket depth, gingival index, gingival bleeding sites, and number of suppurating sites. There was a statistically significant decrease in periodontal pocket depth (19%), gingival index (16%), and the number of bleeding sites (64%) at 90-days in dogs receiving CHgel. Additionally, the number of suppurating sites was lower (93%) at 90-days for the group receiving CHgel. The addition of CHgel effectively controlled the bacterial burden (e.g, Fusobacterium nucleatum) at both day 14 and 90. Gingival cells in culture were shown to rapidly incorporate clindamycin and attain saturation in approximately 20-minutes. In summary, a professional teeth cleaning procedure including root planning and the addition of CHgel improves the gingival index and reduces periodontal pocket depth.     

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.     

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.     

Studies on the occurrence of infectious myonecrosis virus in pond‐reared Litopenaeus vannamei (Boone, 1931) in India

Whiteleg shrimp, Litopenaeus vannamei, with clinical sign of muscle opaqueness with reddish colour at the distal abdominal segments were observed in farms located in West Bengal State, India. The mortality of shrimp in all disease outbreak ponds ranged from 20% to 50%, and mortality increased gradually. The RT‐PCR assay of these samples using primer sets specific to infectious myonecrosis virus (IMNV) revealed its presence in the disease outbreak ponds. The IMNV infection was reproduced in healthy shrimp by intramuscular injection to satisfy River's postulates. The virus caused mortality in intramuscularly challenged shrimp, but failed to cause mortality by oral route. Tissue distribution of IMNV in infected shrimp by RT‐PCR assay revealed the presence of this virus in haemolymph, gill, hepatopancreas and muscle. This study confirms that the disease outbreak which occurred in the shrimp farms located at Purba Medinipur District, West Bengal, India, was due to IMNV.     

Microbial Biomass and Activity in a Laterite Soil Amended with Municipal Solid Waste Compost

The dynamics of soil quality indicators, such as microbial biomass-C, soil respiration, and urease and acid phosphatase activities, in a laterite soil (Typic Haplustalf ) amended with different doses of Calcutta municipal solid waste compost (MSWC) were studied over 120 days of incubation at 30 °C under 60 % soil water holding capacity. The parameters were found to increase with the increase in doses of MSWC. Soil microbial biomass-C (MBC) and soil respiration activity reached peak values at 30 days of incubation and then gradually decreased up to 120 days of incubation. Urease and acid phosphatase activities showed peak values at 60 and 90 days of incubation, respectively. The increase in soil enzyme activities with the fall in MBC suggested that the release of enzymes was associated with lysis of microbial cells at the end of their life cycle. There was no indication of any detrimental effect on soil quality indicators of application of MSWC to soil.     

Is insecticide-induced release of insect neurohormones a secondary effect of hyperactivity of the central nervous system?

Organochlorine and organophosphorus insecticides, in the concentration range of 1–10 μM, induce the release of hyperlipemic (adipokinetic) hormone from the isolated corpora cardiaca of the locust Locusta migratoria. Treatment of locusts with these insecticides in vivo also provokes the release of hyperlipemic hormone. The insecticide-induced release of hormone in vivo was found to precede the onset of poisoning symptoms. The insecticides tested in this study modulate the electrical activity of the isolated corpora cardiaca at doses lower than those required to have similar effects on the central nervous system. The results indicate that the insecticide-induced release of hormone may be mediated by the action of insecticides directly on neurosecretory cells.     

Studies on the role of microorganisms in the metabolism of dieldrin in the epicuticular wax layer of blowflies Calliphora erythrocephala

Microorganisms which inhabit the surface of blowflies, Calliphora erythorcephala, were identified as Bacillus spp., Micrococcus spp., Proteus spp., Streptococcus spp., and yeasts. These microorganisms were able to metabolize [¹⁴C]dieldrin incorporated into their culture media. Micrococcus spp. converted up to 29% of the applied dose of dieldrin to its more polar metabolites while the lowest ability to breakdown dieldrin was associated with Streptococcus spp. which metabolized nearly 0.8% of the applied dose. The addition of sesamex into microbial cultures partly inhibited the breakdown of dieldrin. Cuticular microflora of blowflies were controlled by the topical application of a mixture of gentamicin and amphotericin B. Pretreatment of blowflies with these antibiotics blocked dieldrin metabolism, to a certain degree, in the epicuticular wax layer. The formation of some of the metabolites, which were uniquely confined to the external lipid layer of blowflies, was found to be due to the activity of certain microorganisms. Therefore, microorganisms living on the surface of blowflies were found to play a role in the metabolism of topically applied [¹⁴C]dieldrin. There was a loss in the recovery of the dose of dieldrin applied to blowflies with the lapse of time. This was principally due to its volatilization from treated insects. The volatilization of [¹⁴C]dieldrin from different surfaces was also studied. The loss of the applied dose of dieldrin from various surfaces was in the order of glass > aluminum > fiberglass > DEAE-cellulose paper > silica gel G.     

Effect of mixed cation solutions on hydraulic soil properties

Hydraulic conductivity (K) and soil water diffusivity (D) characterizing water flow under saturated and unsaturated conditions, respectively, were determined for a sandy loam and a clay loam soil, using water with different combinations of total electrolyte concentrations, C (i.e., 20, 40, 80, 125 and 250 meq 1^?1) and sodium adsorption ratios, SAR (i.e., 0, 20, 30, 40, 80 and ∞ mmole $\text{l}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$). Both K and D were found to increase with C and decrease with SAR. In low sodium adsorption ratio ranges (i.e., up to 20) the requirement of electrolyte concentration to maintain relative hydraulic conductivity = 0.5 was relatively more for sandy loam than for clay loam soil. However, the trend for electrolyte concentration requirements for the two soils was reversed at high sodium adsorption ratios (i.e. > 20). A spline function was used to draw the best fitting line through the data points of horizontal absorption experiments.