Forestry insularity effect of four <Emphasis Type="Italic">Mimosa</Emphasis> L. species (Leguminosae-Mimosoideae) on soil nutrients of a Mexican semiarid ecosystem

Information about forestry insularity of plants on soil nutrients will be critical for selecting plant species for agrosilvopastoral or fertility reclamation programs in dry ecosystems. We explored the effects of four Mimosa species (M. lacerata, M. luisana, M. polyantha and M. texana var. filipes) and of rainfall seasonal variation on soil nutrients in a semiarid ecosystem located at the Tehuacán-Cuicatlán Valley, Mexico. Soil samples were taken from outside and under the canopy at three positions (trunk, middle, edge) in all four Mimosa species; ten plants per species. The soil pH, organic matter (SOM), organic carbon (SOC), total nitrogen (Nt), available phosphorus (Pi), and major cations (Ca, Mg, K and Na) were determined. Our results showed that Mimosa species improve the soil under their canopies creating fertile islands with higher SOM, SOC, total N and Pi cycling than the soil in open areas (OA). The insularity effect was significantly species-dependent, where SOM, SOC, Nt and Pi decreased consistently from trunk to OA in all four Mimosa species; however, magnitude varied among species. Likewise, differences in the quantity of soil cations were observed among Mimosa species; though, an insularity gradient trunk-open area was not observed. All these effects were consistent across the species studied and showed little seasonal variability, suggesting a strong forestry insularity of Mimosa species on soil fertility. Of all the four Mimosa species studied, M. lacerata was the most effective in accumulating SOM and nutrients in the soil, for which it would be a good option to implement in agrosilvopastoral or fertility reclamation programs in this semiarid ecosystem.     

Light-dependent development of two competitive species (Rubus idaeus, Cytisus scoparius) colonizing gaps in temperate forest

Forest regeneration can be inhibited by competition for environmental resources (water, nutrients, light) between tree seedlings and some competitive species that are generally light-demanding species developing in gaps. The study’s aim was to quantify the development of two competitive species (Rubus idaeus and Cytisus scoparius) present in the chaîne des Puys, France, relatively to light in gaps inside Picea abies stands. On 29 transects linking the stand to the gap centre (223 points), light intensity was measured (0–80% of relative light) and floristic measurements (cover and height of the different species) were done. Development of both competitive species is positively connected to light, with a bell-shaped curve with a maximum of 40–50% for R. idaeus and a quite constant increase to 80% (maximum of light recorded in the experimentation) for C. scoparius. These results are discussed relatively to understorey vegetation management in order to favour forest regeneration.     

Preliminary study for description of bone tissue responsiveness to prolonged dietary phosphorus deficiency in rainbow trout,Oncorhynchus mykiss (Walbaum)

Prolonged dietary phosphorus (P) deficiency induces a generalized demineralization of bone tissues; however, the differential responsiveness of the diverse tissues to P deficiency remains unknown. Triploid all‐female juvenile rainbow trout (initial mass ~60 g) were fed two practical diets (0.26% and 0.52% digestible P for P‐deficient and P‐sufficient diets) until P‐sufficient fish reached 850 g (241 days; 12°C; 18:6 D:L). Early P‐deficient fish were fed from day 0 the low P‐diet, while late P‐deficient only started feeding at day 134. Growth performance was assessed monthly and carcass samplings were performed at day 0, 134 and 241 to assess mineralization characteristics of different tissues. Ash and content of phosphorus, calcium and magnesium of scales, operculae, ribs and vertebrae as well as the occurrence of abnormalities in ribs and vertebrae were assessed. The tissues most affected by P deficiency were: vertebrae > scales > opercula > ribs. P deficiency affects bone tissues differentially based on the physiological and biomechanical roles of the tissues. As scales were found to be a better indicator to predict abnormalities, understanding of scale metabolism could facilitate P status estimation in fish.     

Seroprevalence of antibodies against Lawsonia intracellularis among growing pigs raised in indoor versus outdoor units

OBJECTIVE: To determine change over time in sero-prevalence of antibodies against Lawsonia intracellularis among growing-finishing pigs housed in indoor versus outdoor facilities. DESIGN: Serologic survey. ANIMALS: 93 pigs born to seropositive gilts and raised in indoor (n = 49) or outdoor (44) growing-finishing facilities. PROCEDURE: Blood samples were collected from the pigs 2, 6, 10, 14, 18, 22, and 26 weeks after birth and tested for antibodies against L intracellularis with an indirect immunofluorescence assay. RESULTS: None of the pigs were seropositive 2 or 6 weeks after birth.Ten weeks after birth, 74% and 76% of pigs in indoor and outdoor growing-finishing facilities were seropositive, respectively, whereas 14 weeks after birth, the percentage of pigs in indoor growing-finishing facilities that were seropositive was substantially higher than the percentage of pigs in outdoor facilities that were. From 18 weeks after birth to the end of the study, none of the pigs in outdoor growing-finishing facilities were seropositive, whereas low percentages of pigs in indoor facilities were seropositive 18, 22, and 26 weeks after birth. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that seroprevalence of antibodies against L intracellularis decreases faster among growing-finishing pigs housed in outdoor facilities than among growing-finishing pigs housed in indoor facilities.     

Genes responsible for anaerobic fumarate and arginine metabolism are involved in growth suppression in Salmonella enterica serovar Typhimurium in vitro, without influencing colonisation inhibition in the chicken in vivo

From a collection of over 2800 Salmonella enterica subspecies Enterica serotype Typhimurium F98 Tn5-TC1 insertion mutants 14 were identified as expressing growth-non-suppressive phenotype under strict anaerobic conditions. Sequence analysis of regions flanking the Tn insertions revealed that most of the selected mutants were defective in genes contributing to the anaerobic fumarate uptake and generation (insertions in dcuA, dcuB and aspA), or to the anaerobic L-arginine utilisation pathway (insertions in STM4467 encoding a putative arginine deiminase, and in between speF encoding ornithine decarboxylase and kdpE coding a response regulator protein). Mutants defective in flagellum synthesis (flhA) were also identified. In contrast to the in vitro results, all the mutants colonised 1-day-old chicks efficiently and suppressed the super-infection of chicks by the parent strain. This clearly indicates that neither of the metabolic pathways mentioned above nor motility play essential roles in lower intestinal tract colonisation.     

江苏森林资源连续清查中确定地类方法的探讨

在江苏森林资源连清查中，采用样点法，最大面积法和实地比例法统计样地在地类频数中节余旌外部不显著。其中实地比例法在祥地中调查较细，能较准确地反映祥地实际情况。     

Storage factors control germination and seedling establishment of freshly harvested true potato seed

Freshly harvested true potato(Solanum tuberosum subsp.andigena, Juz. et Buk.) seeds of the ancient Peruvian cultivar Ccompis were dried to 3.4, 4.2,5.1,6.1, and 7.3% moisture content (Dwt basis) and hermetically stored for 6 months at 15, 30, and 45C. Seeds were humidified to uniform moisture (13%) prior to monthly evaluations of germination at 27 and 17C and seedling performance under variable soil temperature. The effects of treatments on percentage of germination after 8 days at 27C were highly correlated with percentage of emergence at 10 days after sowing and foliage dry weight at 17 days. Germination at 27C increased from negligible to <90% with progressive increases in moisture, temperature, and time in storage. However, germination decreased within the first month of storing seeds at 45C with >5.1% moisture, and after 3 months seeds failed to germinate even after 8 days of lowering the temperature in the germination environment to 17C. Otherwise, germination inhibition at 27C was attributed to dormancy since most seeds readily germinated at 17C. Dormancy was sufficiently released and optimum overall performance was obtained after 2 months of storing seeds at 45C and 4.2% moisture.     

Phylogenetic characterization of canine distemper virus isolates from naturally infected dogs and a marten in Korea

We sequenced the hemagglutinin (H) genes from four canine distemper virus (CDV) isolates obtained from three dogs and a marten in Korea. These sequences were included in subsequent H gene-focused phylogenetic tree analysis of 89 CDV strains. This analysis revealed eight clades designated as EU1, EU2, EU3, NA1, NA2, Asia 1, Asia 2 and Vaccine. Three of the Korean isolates (97Jindo, 98Marten and 07D111) occurred in the Asia 2 group that also contains many Japanese CDV strains isolated in 1998. The remaining Korean strain (07Q72) fell into the Asia 1 group. The 21 H protein sequences of 25 Asia 1 strains are generally predicted to bear nine potential N-linked glycosylation sites. In contrast, the 9 H protein sequences of 12 Asia 2 strains had eight potential N-linked glycosylation sites. The remaining strains had six (98Marten and 07D111) and seven (97Jindo) potential N-linked glycosylation sites.