Configuration and development of root systems of cuttings and seedlings of Eucalyptus globulus

Stem cuttings of Eucalyptus globulus are used within tree improvement programs and for mass deployment. To be successful, cuttings must perform as well or better than seedlings. The root systems of cuttings are fundamentally different from those of seedlings. If these differences influence growth, the differences and their consequences must be identified and the propagation system manipulated to improve performance of the propagules.Cuttings are only a viable alternative to seedlings as planting stock if the method of propagation does not affect their growth and development adversely. Full-sibling cuttings and seedlings of Eucalyptus globulus were compared under controlled environmental conditions to minimise extraneous sources of variation, and to establish whether changes in growth or development were induced by propagation. On three occasions over a period of eight weeks root-collar diameter, shoot height, leaf and stem weight, shoot/root ratios and root system morphology were measured on cuttings and seedlings. Seedlings were taller than cuttings throughout the experiment, but both plant types had similar height growth rates. Diameter growth rates were lower in cuttings than seedlings, and there were differences in both height and diameter growth rates between families. Root system configuration differed between the plant types. Seedlings had strongly gravitropic tap-roots, with two types of primary roots from which secondary roots emerged. Cuttings had no tap roots, and the main structural components of their root systems were adventitious roots formed during propagation. Cuttings did not develop further structural roots during the experiment, whereas seedlings continued to develop primary roots. Individual primary roots of cuttings were longer and had larger mid-point diameters than those of seedlings, but the total length of primary roots was greater in seedlings. Seedlings also had a greater number and total length of secondary roots. Shoot/root ratios, calculated from a range of functional measures, were higher in cuttings than seedlings.     

Zoonotic origin and transmission of Middle East respiratory syndrome coronavirus in the UAE

Since the emergence of Middle East respiratory syndrome coronavirus (MERS‐CoV) in 2012, there have been a number of clusters of human‐to‐human transmission. These cases of human‐to‐human transmission involve close contact and have occurred primarily in healthcare settings, and they are suspected to result from repeated zoonotic introductions. In this study, we sequenced whole MERS‐CoV genomes directly from respiratory samples collected from 23 confirmed MERS cases in the United Arab Emirates (UAE). These samples included cases from three nosocomial and three household clusters. The sequences were analysed for changes and relatedness with regard to the collected epidemiological data and other available MERS‐CoV genomic data. Sequence analysis supports the epidemiological data within the clusters, and further, suggests that these clusters emerged independently. To understand how and when these clusters emerged, respiratory samples were taken from dromedary camels, a known host of MERS‐CoV, in the same geographic regions as the human clusters. Middle East respiratory syndrome coronavirus genomes from six virus‐positive animals were sequenced, and these genomes were nearly identical to those found in human patients from corresponding regions. These data demonstrate a genetic link for each of these clusters to a camel and support the hypothesis that human MERS‐CoV diversity results from multiple zoonotic introductions.     

Small strongyle infection: consequences of larvicidal treatment of horses with fenbendazole and moxidectin

The study was undertaken to evaluate adverse effects of larvicidal treatment in horses naturally infected with cyathostomins. Out of 24 ponies kept on pasture, four animals were housed in September and anthelmintically cured to serve as worm-free controls (group C-0). The others were housed in December. Eight animals each were treated 8 weeks later with 5 x 7.5mg/kg fenbendazole (FBZ) or 1 x 0.4 mg/kg moxidectin (MOX). Four animals remained untreated (group C-i). Two, 4, 6 and 14 days after the end of treatment two animals of each of the treated groups were necropsied together with group C-0 and C-i animals. Infected animals before treatment showed weight loss, eosinophilia, increased plasma protein and globulin contents. Treatment was followed by weight gain and temporal plasma protein and globulin increase. Proportions of CD4+ and CD8+ T lymphocytes in the peripheral blood did not differ between the groups before treatment but dropped significantly temporally after FBZ treatment. Group C-0 was worm-free at necropsy. Group C-i animals contained variable numbers of luminal and tissue cyathostomins. Histological sections showed larval stages in the lamina propria und submucosa surrounded by macrophages. Either treatment was effective against luminal parasites and reduced the number of larvae in the bowel wall beginning 4-6 days after FBZ and 6-14 days after MOX treatment. Histologically, as a first reaction after FBZ application T lymphocytes accumulated around morphologically intact L4 in the submucosa. Subsequently T lymphocytes associated with eosinophils infiltrated the submucosa. Parasites became enclosed by granulomas with eosinophils adhering to and invading the larvae which started to disintegrate on day 4. Later on, particularly on day 14 inflammation extended into the mucosa and was frequently associated with ulcerations. Third stage larvae in general and L4 in the lamina propria, however, seemed not to be affected until day 14 and even then, parasites did usually not generate extensive inflammation. After MOX treatment severe morphologically detectable alterations of tissue larvae could not be observed earlier than day 14. Different from FBZ treatment, larvae disintegrated and were obviously resorbed without causing severe inflammation in the gut wall. In conclusion treatment with either drug was efficacious against tissue larvae of cyathostomins but there may be different clinical consequences: in contrast to MOX effects, killing of larvae due to FBZ was associated with severe tissue damage, which clinically may correspond to reactions caused by synchronous mass emergence of fourth stage larvae, i.e., may mimic larval cyathostominosis.     

Biological activity of volatiles from marine and terrestrial bacteria

The antiproliferative activity of 52 volatile compounds released from bacteria was investigated in agar diffusion assays against medically important microorganisms and mouse fibroblasts. Furthermore, the activity of these compounds to interfere with the quorum-sensing-systems was tested with two different reporter strains. While some of the compounds specific to certain bacteria showed some activity in the antiproliferative assay, the compounds common to many bacteria were mostly inactive. In contrast, some of these compounds were active in the quorum-sensing-tests. γ-Lactones showed a broad reactivity, while pyrazines seem to have only low intrinsic activity. A general discussion on the ecological importance of these findings is given.     

Evaluation of a newly developed real-time PCR for the detection of Taylorella equigenitalis and discrimination from T. asinigenitalis

A 'culture-LightCycler PCR' assay has been developed for the detection of Taylorella equigenitalis, the causative agent of contagious equine metritis (CEM) in horses. The primers and hybridisation probes were derived from the 16S rDNA sequence. Their specificity was determined in two closely related organisms and six commensal bacteria of the genital tract. The assay was specific for T. equigenitalis and discriminates T. asinigenitalis isolates. It also avoids misidentifications of morphologically and phenotypically similar organisms. The sensitivity was evaluated in comparison to a standard bacteriological culture method. It detected T. equigenitalis in 10 of 52 samples that had not been identified bacteriologically. The results indicated that the assay had a greater sensitivity. This is the first real-time PCR for the detection of T. equigenitalis and avoids PCR carry-over contamination. The 'culture-LightCycler PCR' assay is specific, sensitive and reproducible, and can be used effectively for the detection of T. equigenitalis infections.     

Chloride content and biomass partitioning in Eucalyptus hybrids grown on saline sites

Eucalyptus camaldulensis × globulus and E. camaldulensis × grandis hybrids have been developed to combine the salt–waterlogging tolerance and high-quality wood fibre of their respective parents. The aim is to develop trees that will grow in relatively dry and/or saline environments and provide commercial wood products. Previous studies indicate that the hybrids exhibit faster growth than either of their pure species parents, and that there are significant differences in growth rates between them. We undertook a comparative study of the partitioning of above-ground biomass (AGB) to examine biomass and chloride (Cl) allocation of trees growing on two saline-irrigated sites in south-eastern Australia. Eucalyptus camaldulensis × globulus had a higher proportion of AGB in leaves (20–29% cf. 15–16%), and lower proportion in live branches (3–10% cf. 6–14%) than E. camaldulensis × grandis. The concentration of Cl was highest in the stembark (4.2–9.6 g kg⁻¹) and lowest in the stemwood (0.6–2.0 g kg⁻¹), suggesting that trees can export Cl through bark shedding. Total Cl content was strongly related to volume under bark (R² = 0.99), and differences in partitioning of Cl into tree components differed between the hybrids in the same way as AGB. Preferential partitioning of Cl to live branches rather than foliage in E. camaldulensis × grandis suggests that this hybrid may be compartmentalising Cl to reduce the risk of Cl toxicity in the leaves.     

Physiological and blood biochemical variables in horses exercising on a treadmill submerged in water

The blood lactate concentration (LA) and heart rate (HR) of 10 horses exercising in water on a treadmill were examined. With the water at 10 and 50% of the withers height (WH), the blood LA increased up to mean values around 1.9 mm during the standardized exercise test (SET) until after step 3 of 5 (each step lasted 5 min, speed increasing step by step). Thereafter, blood LA of horses remained constant, while with the water at 80% of WH, the blood LA decreased from the mean peak of 2.16 ± 0.62 mm after the 4th step. The HR of the horses increased to 132 ± 14 beats/min until the 3rd step of SET with the water at 10% of WH, up to the 2nd step with the water at 50% (134 ± 10 beats/min) and up to the 1st step only with the water at 80% of WH (134 ± 10 beats/min). In another SET, horses were exercised five times for 5 min at the maximal attainable speed of 5.5 m/s in water at 20% of the withers height in step 1, 35% in step 2, 49% in step 3, 63% in step 4 and 77% in step 5. On using this SET, blood LA increased to 1.91 ± 0.25 mm until after the 2nd step and decreased after the 3rd step. The HR increased between before commencing SET and the 1st step (143 ± 13 beats/min) and remained constant thereafter. In conclusion, increasing water height and speed of exercise does not augment continuously blood LA and HR of horses exercising in water treadmills.     

Assessment of salt tolerance in eucalypts using chlorophyll fluorescence attributes

Chlorophyll fluorescence attributes were investigated for their potential as rapid, non-invasive indices of salt stress in eucalypts. After representative clones of E. camaldulensis and E. urophylla×grandis were subjected to salinity treatments, dark-adapted and quenching attributes did not show consistent responses to salinity stress. The light-adapted attribute F _ds, when measured in a controlled environment, did decline, often before physical symptoms of stress were visible. This value is required for the derivation of the effective quantum yield, and each measurement can be acquired and automatically recorded in a few seconds, permitting the rapid survey of large groups in a propagation facility. Monitoring of plants, that were treated with increasing concentrations of NaCl over time, permitted overall ranking of the responses of groups of clones and seedlings. Usually the data were heteroscedastic, so non-parametric methods of statistical analysis were used, and P0.01 for ascribing significance to differences. Also, following the responses of individuals within clones and provenances showed the method should be useful for the early detection of particularly susceptible or resistant seedlings.