Effect of supplementation of rice bran and fumarate alone or in combination on in vitro rumen fermentation,methanogenesis and methanogens

This study investigated the effect of fumarate (FUM) and rice bran (RB), alone and together, on in vitro rumen fermentation, methanogenesis and methanogens. In vitro incubation was performed with six media that were either unsupplemented (control) or supplemented with 10% RB, 5 mmol/L FUM, 10% RB + 5 mmol/L FUM, 10 mmol/L FUM, or 10% RB + 10 mmol/L FUM. Methane (CH₄) production, dry matter digestibility, CH₄ per digested dry matter, total short‐chain fatty acid (SCFA) production, proportion of SCFA, acetate : proprionate ratio, production of NH₃‐N, and population density of rumen microbes were determined. Supplementation with 10% RB + 10 mmol/L FUM yielded a 36% decrease in CH₄ production compared to the control. Supplementation of FUM, in the presence or absence of RB, provided increases in total SCFA production and propionate proportion up to 61% and 31%, respectively. Total bacteria, methanogens and protozoa populations were significantly (P < 0.05) decreased with the 10% RB + 10 mmol/L FUM supplementation. The effect of anti‐methanogenesis of FUM was enhanced by the addition of RB. Notably, the CH₄ production attenuation was achieved by 10% RB + 10 mmol/L FUM without reduction of digestibility or of ruminal fermentation.     

Effects of livestock grazing on the spatial heterogeneity of net soil nitrogen mineralization in three types of Mongolian grasslands

Purpose

Small-scale soil heterogeneity relates to productivity and biodiversity and is crucial to understand. Soil heterogeneity could be affected by vegetation structure, and large mammal grazers could modify it through herbivory and excretion. The objective is to clarify the effects of livestock grazing on the small-scale (～3 m) soil heterogeneity in three types of Mongolian grasslands.

Materials and methods

We sampled soils from inside (ungrazed) and outside (grazed) exclosures in three vegetation types: forest-steppe, shrub-steppe, and desert-steppe. We measured laboratory rates of soil net nitrogen (N) mineralization and net nitrification and geostatistically analyzed heterogeneity.

Results and discussion

Average rates of net N mineralization and net nitrification were lower at shrub-steppe and desert-steppe and were decreased by grazing. Semivariograms showed vegetation-induced heterogeneity in ungrazed plots, except for net nitrification at forest-steppe. We found linear change with distance under dense and uniform vegetation at forest-steppe, 1.3 m patch under patchy vegetation at shrub-steppe, and linear change, but with much smaller semivariance, under sparse and poor vegetation at desert-steppe. At forest-steppe, grazing randomized the spatial patterns of net N mineralization and net nitrification. At shrub-steppe and desert-steppe, grazing greatly decreased the semivariances of net N mineralization and net nitrification as well as their averages, and the soil heterogeneity was virtually disappeared.

Conclusions

Grazing in Mongolian grasslands homogenized the spatial patterns of net N mineralization and net nitrification, irrespective of their original spatial patterns determined by the differences in vegetation structure.     

Sesbania spp., Aeschynomene indica and Crotalaria spp. are amide-exporters

Abstract

Extract

Leguminous plants consist of two groups, amide-exporting and ureide-exporting plants. The former legumes export a large fraction of fixed-N in the form of amides (asparagine and glutamine), and the latter legumes in the form of ureides (allantoic acid and allantoin). Another characteristic of the nodules is the enrichment in ¹⁵N. There are two types of legumes: one characterized by the enrichment with ¹⁵N in N₂-fixing nodules, in contrast to the other where the enrichment does not occur. The first investigation by Shearer et al. (1982) suggested that the nodules exporting fixed-N in the form of ureides were enriched in ¹⁵N unlike those exporting it in the form of amides. Soybeans, mungbean, and cowpea belong to the former group and groundnut, alfalfa, white clover to the latter. Although pea and faba bean were first classified into the latter group (Shearer et al. 1982), a recent investigation (Yoneyama 1988) showed that these nodules were also enriched in ¹⁵N.     

Occurrence of Guanidino Compounds in Several Plants

The stored nitrogen in perennial plants plays an important role in their regrowth in spring. Free L-arginine is one of the major forms of stored nitrogen (6, 9) .. LArginine is metabolized via the urea cycle in animal and plant tissues. In animal tissues, L-arginine is also metabolized via r-guanidinobutyramide, r-guanidinobutyric acid, and r-aminobutyric acid to the TCA cycle. In plant tissues, few attempts have been made to study arginine-metabolic routes other than the urea cycle. In white spruce tissues (3), L-arginine is metabolized via r-guanidinobutyric acid. Also in citrus tissues (4, 5), the operation of the same metabolic route has been reported. In these experiments, it was observed that various guanidino compounds reacted with the Sakaguchi reagent.

To obtain more information about the guanidino compounds involved in the arginine metabolism, the analytical system was evaluated and the presence of these compounds in several plant species was examined.     

Cell wall metabolism of pear fruit on the tree after 2,4-DP treatment

Summary

The effect of 2,4-dichlorophenoxy-propionic acid (2,4-DP) on fruit ripening on the tree was investigated in `La France' pears (Pyrus communis L.). Forty-five ppm, 2,4-DP solution was applied at 159 d after full bloom (DAFB), which was optimum harvest date for `La France' pears. They were compared with fruit harvested at 159 DAFB and placed in a controlled room with a 208C and 90% r.h. After harvest, the fruit firmness decreased dramatically 13 d after harvest (DAH). In 2,4±DP treatment, the levels decreased gradually 13 d after treatment (172 DAFB). In the untreated control, the levels also showed a slight decrease with time. Final ethylene concentration was almost the same in harvested and 2,4-DP treated fruit, but lower in the untreated control. In each treatment, water-soluble polyuronide (WSP) concentrations increased with time and hexametaphosphate-soluble polyuronide (HMP) and HCl-soluble polyuronide (HP) concentrations decreased. WSP concentration increased rapidly 20 DAH in harvested fruit and 194 DAFB in 2,4-DP treatment. Harvested and 2,4-DP treated fruit reached the edible condition on 17 DAH and 194 DAFB, respectively. Pectinesterase (PE) activity increased slightly with time for all treatments, showing no significant difference between treatments. Polygalacturonase (PG) activity increased gradually in all cases, being higher in 2,4-DP treated fruit than in control fruit left on the tree. These results suggest that 2,4-DP treatment before harvest induces pear fruit softening. This implies that 2,4-DP may be used as a replacement for low-temperature storage to promote the ripening, and good quality ripe fruit with buttery and juicy texture may be harvested on the tree.     

Changes of abscisic acid and its metabolite during development of apple fruit

Summary

Free and conjugated abscisic acid (ABA) and phaseic acid (PA) concentrations in the seed and pulp of apples (Malus pumila Mill. cv. Tsugaru) and ABA metabolism in the fruit after cis-(+)-ABA application were investigated. In the seed, the levels of cis- and trans-ABA and conjugated cis- and trans-ABA showed a general increase towards harvest, except for the decrease of cis-ABA at 131 d after full bloom (DAFB) (harvest). PA levels reached a peak at 41 DAFB, then decreased until harvest. The levels of free ABA in the seed were higher than those in the pulp. In the pulp, the levels of cis-ABA increased gradually from 20 DAFB and rapidly from 111 DAFB towards harvest. The levels of trans-ABA and conjugated trans-ABA also showed similar changes to cis-ABA, i.e. increased steeply from 111 DAFB. In contrast, the level of conjugated cis-ABA was the highest at 20 DAFB, then fell rapidly until 111 DAFB and then increased again towards harvest. PA showed the highest level at 20 DAFB, then decreased gradually until 111 DAFB and then increased again towards harvest. It is therefore assumed that not only cis-ABA but also its metabolite may be associated with the ripening of apple fruit. Cis- and trans-ABA and conjugated cis- and trans-ABA concentrations in cis-(+)-ABA treated fruit increased significantly on 11 d after ABA application (122 DAFB). However, at 20 d after cis-(+)-ABA application, only trans-ABA and conjugated trans-ABA showed higher levels than those of the untreated control, while the levels of cis-ABA and conjugated cis-ABA fell to the same levels as the untreated control. PA levels did not show significant increase on 11 and 20 d after cis-(+)-ABA application. These results suggest that cis-(+)-ABA treated exogenously to apple fruit may eventually metabolize to trans-ABA, conjugated trans-ABA and further metabolites.     

Expression of anthocyanin biosynthetic genes in Malus sylvestris L. ‘Mutsu’ non-red apples

Summary

The expression of five anthocyanin biosynthetic genes of chalcone synthase (MdCHS). flavanane 3-hydroxylase (MdF3H). dihydroflavonol 4-reducase (pDFR), anthocyanidin synthase (MdANS) and UDP glucose-flavonoid 3-O-glucosyltransferase (pUFGluT) was investigated during fruit development in the skin of non-red ‘Mutsu’ apples (Malus sylvestris (L) Mill. van domestica (Borkh) Mansf.). MdCHS, MdF3H and pDFR appeared in the skin of non-bagged fruit from 81 d after full bloom (DAFB) to 167 DAFB, but MdANS and pUFGluT did not appear. When the fruit was bagged during fruit development and unbagged before the maturation, anthocyanin was produced in the exposed portion but not in the shaded portion. All five genes including MdANS and pUFGluT were detected in the exposed portion at 165 DAFB. In the shaded portion, MdANS was detected, but pUFGluT was not. The skin colour of the shaded portion after unbagging in the bagged fruit was more yellow than that in non-bagged fruit. This result suggests that the yellowing of the skin may relate to the expression of MdANS. All five anthocyanin biosynthetic genes were detected at 20 DAFB despite the absence of anthocyanin. The roles of genes in the anthocyanin biosynthetic pathway may differ from one development stage to the next.     

Antioxidative compounds from leaves of Tahongai (<Emphasis Type="Italic">Klienhovia hospita</Emphasis>)

In our effort to find antioxidant agent, we focused on Tahongai (Kleinhovia hospita) which have been used traditionally in Indonesia as medicinal herbal to cure liver disease. Based on the biologically guided fractionation using DPPH radical scavenging assay, eleutherol and kaempferol 3-O-β-d-glucoside was isolated from the leaves of K. hospita. Kaempferol 3-O-β-d-glucoside (1) and eleutherol (2) scavenged the radical with IC₅₀ of 71.4 and 491.8 μM, respectively. In addition, both of the compounds did not exhibit cytotoxicity on HepG2 cells.     

No evidence of horizontal infection in horses kept in close contact with dogs experimentally infected with canine influenza A virus (H3N8)

Background

Since equine influenza A virus (H3N8) was transmitted to dogs in the United States in 2004, the causative virus, which is called canine influenza A virus (CIV), has become widespread in dogs. To date, it has remained unclear whether or not CIV-infected dogs could transmit CIV to horses. To address this, we tested whether or not close contact between horses and dogs experimentally infected with CIV would result in its interspecies transmission.

Methods

Three pairs of animals consisting of a dog inoculated with CIV (10^8.3 egg infectious dose₅₀/dog) and a healthy horse were kept together in individual stalls for 15 consecutive days. During the study, all the dogs and horses were clinically observed. Virus titres in nasal swab extracts and serological responses were also evaluated. In addition, all the animals were subjected to a gross pathological examination after euthanasia.

Results

All three dogs inoculated with CIV exhibited clinical signs including, pyrexia, cough, nasal discharge, virus shedding and seroconversion. Gross pathology revealed lung consolidations in all the dogs, and Streptococcus equi subsp. zooepidemicus was isolated from the lesions. Meanwhile, none of the paired horses showed any clinical signs, virus shedding or seroconversion. Moreover, gross pathology revealed no lesions in the respiratory tracts including the lungs of the horses.

Conclusions

These findings may indicate that a single dog infected with CIV is not sufficient to constitute a source of CIV infection in horses.