Peptidases of Trichobilharzia regenti (Schistosomatidae) and its molluscan host Radix peregra S. Lat. (Lymnaeidae): construction and screening of cDNA library from intramolluscan stages of the parasite

Trichobilharzia regenti is a neurotropic bird schistosome,causing cercarial dermatitis in humans. In this study, ZAP cDNA expression library from Radix peregra s. lat. hepatopancreases containing intramolluscan stages of T. regenti was constructed and screened using PCR with specific and degenerate primers, designed according to previously described serine and cysteine peptidases of other parasite species. Full-length sequences of cathepsins B1 and L, and two serine peptidases, named RpSP1 and RpSP2, were obtained.The protein-protein BLAST analysis and parallel control reactions with template from hepatopancreases of T. regenti non-infected snails revealed that only cathepsin B1 was of parasite origin. The remaining sequences were derived from the snail intermediate host, which implies that the initial source of parasite mRNA was contaminated by snail tissue.Regardless of this contamination, the cDNA library remains an excellent molecular tool for detection and identification of bioactive molecules in T. regenti cercariae.     

Normal electrocardiographic and echocardiographic (M-mode and two-dimensional) values in Polish Landrace pigs

Background

Swine are recognized animal models of human cardiovascular diseases. Normal values of cardiac morphology and function have been published for swine but for smaller number of pigs and not for swine whose weights ranged up 100 kg. In order to improve the value of results of an investigation on cardiac morphology and function in swine when such data are extrapolated to humans, the aim of this study was to document electrocardiographic and echocardiographic measures of cardiac morphology and function in swine. The study comprised 170 single and repeated measurements that were made in 132 healthy domestic swine (Sus domesticus) whose weights ranged between 20-160 kg and were used as controls in three different experiments. All electrocardiographic and echocardiographic measurements in all swine were done under general anaesthesia.

Results

Statistically significant correlations were found between body weight and heart rate (HR), the duration of the P-wave, the duration of the QRS interval, the duration of the QT interval, and the corrected QT ratio (QTc). Since body weight was positively correlated with age, statistically significant correlations were also found between age and HR, the duration of the P-wave, the duration of the QRS interval, the duration of the QT interval, and the QTc. We found that the thickness of the left ventricular wall and the internal diameter of the left ventricle increased with age and body weight. We also found positive trends between body weight and ejection fraction and body weight and fractional shortening. We also found a positive relationship between age, body weight, and the ratio of the left ventricular internal diameter to its wall thickness, as well as the relative left atrial size.

Conclusion

Many electro- and echocardiographic measures of cardiac morphology and function of healthy swine are related to their body weight. When the electro- and echocardiographic measures of domestic swine and humans are compared, the most comparable electrocardiographic values are those that were determined in swine whose body weights are not greater than 70 kg. In contrast, the most comparable echocardiographic measures are those that were determined in swine with a body weight of 40–110 kg.     

Settling and raising postlarval abalone Haliotis diversicolor supertexta (Lischke) on microparticulate diets embedded in a layer of alginate

Two 21 day experiments were conducted to determine whether microparticulate diets could be used to substitute for diatoms for raising (Experiment 1) as well as settling and on‐growing (Experiment 2) Haliotis diversicolor supertexta postlarvae. The experiments were conducted in 10 L flow‐through tanks and each diet had three replicate tanks. In experiment 1, three experimental microparticulate diets supplied by a commercial feed company, labelled SF‐15, SF‐15 (T) and JFY‐13–1, were used, and in experiment 2, SF‐15 and SF‐15 (T). Artificial diets were compared to diatoms in terms of supporting growth and survival. The survival rate for experiment 1 was lowest for JFY‐13–1 (0%) and highest for diatoms (12.9±0.8%). The final size of postlarvae fed SF‐15 and SF‐15 (T) was significantly greater than that of postlarvae fed diatoms, 973±193 μm and 996±220 μm compared to 786±141 μm. In experiment 2, a total number of 501 larvae settled onto plates covered with SF‐15, 254 on SF‐15 (T) and 1085 on diatoms. The highest survival rate was 33.1±6.9% for SF‐15 and the lowest was 17.3±5.0% for diatoms. However, the final length of postlarvae fed diatoms was significantly greater than SF‐15 and SF‐15 (T); 1018±379 μm compared to 728±89 μm and 717±90 μm. The artificial micro diets used in this study were comparable to diatoms in terms of grow and survival of postlarval H. diversicolor supertexta.     

Methanotrophy-driven accumulation of organic carbon in four paddy soils of Bangladesh

Biological methane oxidation is a crucial process in the global carbon cycle that reduces methane emissions from paddy fields and natural wetlands into the atmosphere.However,soil organic carbon accumulation associated with microbial methane oxidation is poorly understood.Therefore,to investigate methane-derived carbon incorporation into soil organic matter,paddy soils originated from different parent materials(Inceptisol,Entisol,and Alfisol) were collected after rice harvesting from four major rice-producing regions in Bangladesh.Following microcosm incubation with 5%(volume/volume)¹³ CH₄,soil¹³ C-atom abundances significantly increased from background level of 1.08% to 1.88%–2.78%,leading to a net methane-derived accumulation of soil organic carbon ranging from 120 to 307 mg kg^-1.Approximately 23.6%–60.0% of the methane consumed was converted to soil organic carbon during microbial methane oxidation.The phylogeny of¹³ C-labeled pmoA(enconding the alpha subunit of the particulate methane monooxygenase) and 16 S rRNA genes further revealed that canonical α(type II) and γ(type I) Proteobacteria were active methane oxidizers.Members within the Methylobacter-and Methylosarcina-affiliated type Ia lineages dominated active methane-oxidizing communities that were responsible for the majority of methane-derived carbon accumulation in all three paddy soils,while Methylocystis-affiliated type IIa lineage was the key contributor in one paddy soil of Inceptisol origin.These results suggest that methanotroph-mediated synthesis of biomass plays an important role in soil organic matter accumulation.This study thus supports the concept that methanotrophs not only consume the greenhouse gas methane but also serve as a key biotic factor in maintaining soil fertility.     

Composted biosolids as a source of iron for hybrid poplars (<Emphasis Type="Italic">Populus</Emphasis> sp.) grown in northwest New Mexico

Composted sewage sludge (biosolids) supply plant available Fe and may represent a sustainable alternative to more costly chelated Fe fertilizers currently used to supplement nutrition in hybrid poplar test plots of elevated soil pH. To test the response of poplars, field plots were amended with composted biosolids at two agricultural rates: 22.75 and 44.5 Mg ha⁻¹. Iron EDDHA served as a fertilizer check and control plots received no amendment. The hybrid poplar OP-367 (Populus deltoides × P. nigra) was planted on a 3.6 m grid spacing. Significant amounts of P and Fe originating from the sewage treatment process were detected in soils 13 months after amending. Chlorosis evaluated with a SPAD-502 meter, showed that poplars amended with biosolids remained the least chlorotic and had greater tree growth when compared to Fe EDDHA and control plots during two growing seasons. Biosolids show promise as a cost effective alternative for the remediation of Fe chlorosis in hybrid poplar agroforestry plantations and present new opportunities in northwestern New Mexico for municipalities seeking solid waste land disposal options.     

The contribution of competition to tree mortality in old-growth coniferous forests

Competition is a well-documented contributor to tree mortality in temperate forests, with numerous studies documenting a relationship between tree death and the competitive environment. Models frequently rely on competition as the only non-random mechanism affecting tree mortality. However, for mature forests, competition may cease to be the primary driver of mortality.We use a large, long-term dataset to study the importance of competition in determining tree mortality in old-growth forests on the western slope of the Sierra Nevada of California, U.S.A. We make use of the comparative spatial configuration of dead and live trees, changes in tree spatial pattern through time, and field assessments of contributors to an individual tree's death to quantify competitive effects.Competition was apparently a significant contributor to tree mortality in these forests. Trees that died tended to be in more competitive environments than trees that survived, and suppression frequently appeared as a factor contributing to mortality. On the other hand, based on spatial pattern analyses, only three of 14 plots demonstrated compelling evidence that competition was dominating mortality. Most of the rest of the plots fell within the expectation for random mortality, and three fit neither the random nor the competition model. These results suggest that while competition is often playing a significant role in tree mortality processes in these forests it only infrequently governs those processes. In addition, the field assessments indicated a substantial presence of biotic mortality agents in trees that died.While competition is almost certainly important, demographics in these forests cannot accurately be characterized without a better grasp of other mortality processes. In particular, we likely need a better understanding of biotic agents and their interactions with one another and with competition.     

Age determination of large live trees with inner cavities: radiocarbon dating of Platland tree,a giant African baobab

• Introduction   

For large trees without a continuous sequence of growth rings in their trunk, such as the African baobab (Adansonia digitata L.), the only accurate method for age determination is radiocarbon dating. As of today, this method was limited to dating samples collected from the remains of dead specimens.