Mechanizsed microsite preparation and direct seeding of Pinus sylvestris in boreal forests — a way to create desired spacing at low cost

The main objective of this study was to examine the cost, flexibility, and appropriate scale of mechanized microsite preparation (MP), in combination with mechanical direct seeding of Pinus sylvestris L. with orchard seed. This technique was tested at four boreal forest sites in Northern Sweden. Orchard and stand seeds were sown with and without MP. The use of orchard seed increased seedling establishment by 41% and the use of MP increased seedling establishment by 47%, respectively, after two years. The best substrates for sowing when using MP were OA_h-, E- and BC-horizon, in ranked order. The use of orchard seed compared to stand seed increased mean seedling height by 25% after four years. These trials suggest that to obtain a density of 5,000 stems ha^-1 four years after seeding, 61,000 viable stand seeds or 41,000 orchard seeds ha^-1 should be sown if MP is not used. If MP is used, seeding rate could be reduced by about 32%. By using MP, and by further improving scarification technique so that all scarified area is thin OA_h-horizon, we predict that only 32,000 stand seeds or 22,000 orchard seeds ha^-1, i.e., half the dosage, should be needed. Under these optimal conditions, it would be necessary to sow about six and four germinable stand and orchard seeds, respectively, to ensure one seedling after four years. Furthermore, regeneration cost would be less than a third that of planting.     

Liver histology and histomorphometry in hybrid sorubim (Pseudoplatystoma reticulatum × Pseudoplatystoma corruscans) reared on intensive fish farming

This study aimed to characterize the liver histology and histomorphometry in sorubim hybrid of different categories (nursery, growth and grow‐out) reared on fish farming. The categories were defined considering body weight (BW): nursery category (n = 5): BW = 37.06 ± 6.00 g (31.6–45.3 g); growth category (n = 5): BW = 310.40 ± 53.80 g (242.1–376.4 g) and grow‐out category (n = 5): BW = 874.28 ± 27.59 g (846.2–913.1 g). Liver fragments were processed to paraffin inclusion, and sections were stained by haematoxylin and eosin (H&E), PAS (Periodic Acid Schiff) and Perl's staining to histology, histomorphometry and density volumetric of liver structures; glycogen analysis and to detect ferric irons (Fe³⁺) respectively. The hepatosomatic index decreased between the categories (P < 0.01). The percentage of PAS‐positive hepatocytes in the nursery category was higher (P < 0.05) in relation to the growth and grow‐out categories. The hepatocytes from all fish were positive to Perl's staining. The density volumetric of liver structures did not differ among categories except to blood vessels were higher (P < 0.01) in the nursery and growth. The area (μm²) and perimeter (μm) of hepatocytes, and the area (μm²), perimeter (μm) and volume (μm³) of the nuclei from grow‐out fish were lower (P < 0.01) than those from the nursery and growth categories. Changes in morphometric characteristics of hepatocytes may result from metabolic changes associated with body growth surubins; therefore, these morphometric characteristics of liver tissue can be used as functional biomarkers for the assessment of fish health and nutrition status.     

Research into fluorinated pyrethroid alcohols—an episode in the history of pyrethroid discovery

An account of pyrethroid research from 1975 to 1985 at Bayer AG is given. The exploitation of fluorine chemistry for this purpose led to increased activity of known 3-phenoxybenzyl pyrethroid esters and to the commercialisation of the broad-spectrum insecticide cyfluthrin, the particularly tick-toxic flumethrin and the rapid-acting household insecticides fenfluthrin and transfluthrin. The last two constituted in 1976 a novel type of pyrethroid, based on polyfluorinated benzyl alcohols, off the mainstream of published pyrethroid research. Transfluthrin, the single isomer (1R)trans-permethric acid ester of 2,3,5,6-tetrafluorobenzyl alcohol has just been introduced to the market. The history of its discovery and structure–activity data as well as resistance considerations regarding cyfluthrin, are presented. © 1998 SCI.     

Segregation of microsatellite loci in second generation hybrid striped bass (<Emphasis Type="Italic">Morone saxatilis</Emphasis> × <Emphasis Type="Italic">Morone chrysops</Emphasis>)

Within the framework of a larger project aimed to assess the potential of second generation hybrid striped bass for German aquaculture the genotypic segregation of five microsatellite loci was analysed in two progeny lots (n = 74 and 76, respectively). There was no consistent correlation between microsatellite genotypes and phenotypic category (white bass, hybrid, or striped bass). None of the individuals expressed neither only white bass nor only striped bass genotypes at all five loci. On the other hand, only hybrid genotypes at all five loci were detected in three individuals of lot 1 and four individuals of lot 2. Single loci tests for conformity of microsatellite genotypic segregation with Mendelian rules revealed significant deviations (P < 0.05) in four cases for lot 1 and in three cases for lot 2. If pooled over all five loci, both lots displayed highly significant deviations (P < 0.01) with an excess of hybrid genotypes and a deficiency of white bass genotypes. It is concluded that stabilizing selection performed on hybrid genotypes might be a suitable approach for practical aquaculture in Europe if the goal is to become independent of first generation hybrid fry supply and/or if establishing domesticated brood stocks of both parental species is impossible. However, more detailed studies on the characteristics and performance of multiple hybrid generations are needed.     

Ligands of the nicotinic acetylcholine receptor as insecticides

Insect nicotinic acetyl receptors (nAChR) are targets of growing importance and, since the early 1990s, the number of such highly effective insecticides as imidacloprid and spinosyn has grown. Several natural compounds, eg dihydro-β-erythroidine, methyl caconitine and paraherquamide, showing high affinity to the same receptor, were considerably less active as insecticides, most likely because of their antagonistic action. Our observations on aphids after ingestion of the antagonistic compound dihydro-β-erythroidine revealed anti-feedant-like properties. As a consequence, the symptomology of poisoning was totally different between agonists and antagonists of the nAChR. Electrophysiological (whole-cell voltage clamp) measurements in isolated housefly neurones revealed that agonism seems to be a prerequisite for insecticidal activity. Furthermore, we were able to demonstrate the existence of two different subtypes of the nAChR in isolated locust neurones with different pharmacology and ion-channel properties.     

长沙冷季型草坪草引种试验

为了给长沙地区草坪建植和草种选用提供栽培依据,3年来对高羊茅、草地早熟禾、粗茎早熟禾、翦股颖、多年生黑麦草5个冷季型草坪草的42个品种进行了引种栽培试验,筛选出绿色期长、抗逆性好、适合长沙气候的冷季型草坪草品种有高山、浪潮、优异、华盛顿、公园、兰肯、猎狗5号、交战2号、L5、侵略者、百都11个。     

Dissolved and colloidal phosphorus fluxes in forest ecosystems—an almost blind spot in ecosystem research

Understanding and quantification of phosphorus (P) fluxes are key requirements for predictions of future forest ecosystems changes as well as for transferring lessons learned from natural ecosystems to croplands and plantations. This review summarizes and evaluates the recent knowledge on mechanisms, magnitude, and relevance by which dissolved and colloidal inorganic and organic P forms can be translocated within or exported from forest ecosystems. Attention is paid to hydrological pathways of P losses at the soil profile and landscape scales, and the subsequent influence of P on aquatic ecosystems. New (unpublished) data from the German Priority Program 1685 “Ecosystem Nutrition: Forest Strategies for limited Phosphorus Resources” were added to provide up‐to‐date flux‐based information. Nitrogen (N) additions increase the release of water‐transportable P forms. Most P found in percolates and pore waters belongs to the so‐called dissolved organic P (DOP) fractions, rich in orthophosphate‐monoesters and also containing some orthophosphate‐diesters. Total solution P concentrations range from ca. 1 to 400 µg P L^?1, with large variations among forest stands. Recent sophisticated analyses revealed that large portions of the DOP in forest stream water can comprise natural nanoparticles and fine colloids which under extreme conditions may account for 40–100% of the P losses. Their translocation within preferential flow passes may be rapid, mediated by storm events. The potential total P loss through leaching into subsoils and with streams was found to be less than 50 mg P m^?2 a^?1, suggesting effects on ecosystems at centennial to millennium scale. All current data are based on selected snapshots only. Quantitative measurements of P fluxes in temperate forest systems are nearly absent in the literature, probably due to main research focus on the C and N cycles. Therefore, we lack complete ecosystem‐based assessments of dissolved and colloidal P fluxes within and from temperate forest systems.     

Dereplication and Chemotaxonomical Studies of Marine Algae of the Ochrophyta and Rhodophyta Phyla

Dereplication and chemotaxonomic studies of six marine algae of the Ochrophyta and one of the Rhodophyta phyla resulted in the detection of 22 separate compounds. All 16 secondary metabolites, including four new compounds (16–19), could be rapidly dereplicated using HPLC-NMR and HPLC-MS methodologies in conjunction with the MarinLit database. This study highlights the advantages of using NMR data (acquired via HPLC-NMR) for database searching and for the overall dereplication of natural products.     

Lesions in the Larynx of Wistar RccHan: WIST Rats

Specific regions in the rat larynx exhibit cellular changes in response to inhaled xenobiotics. These regions include the base of the epiglottis, ventral pouch, and medial surfaces of the vocal processes of the arytenoid cartilages. 1 , 2 In order to collect information on the usefulness of trimming techniques, the influence of different vehicles, the impact of different application routes in toxicity studies, and differences between induced vs. spontaneous lesions, the data obtained from a large number of inhalation and non-inhalation studies performed in Wistar RCCHan(TM): Wist rats at Harlan Laboratories Ltd Switzerland, all evaluated or reviewed by the same pathologist, were compiled for a detailed review. The value of different trimming techniques was deemed to be greatest for transverse and sagittolongitudinal section techniques, as compared to horizontolongitudinally section techniques. The comparison of lesions encountered in control rats of inhalation studies treated with different vehicles did not reveal differences in the type, distribution pattern, incidence and/or severity of spontaneous lesions. The types of lesions were also independent of different application routes in non-inhalation studies compared to inhalation studies. The pattern of spontaneous lesions in the rodent larynx was determined by degenerative and inflammatory lesions starting most often in the submucosal glands by desiccated secretion followed by mineralization and local inflammation or were induced by impacted foreign bodies. Squamous metaplasia was recorded in the respiratory epithelium overlaying the ventral gland as a spontaneous lesion in male Wistar rats from inhalation studies with a maxim of 20.0% in an inhalation oncogenicity study. Induced metaplastic changes recorded in the larynx were reversible. Other induced lesions in inhalation studies consisted of submucosal edema, necrosis, inflammation and/or granuloma. Induced lesions in non-inhalation studies were found to be exclusively related to reflux laryngitis or food impaction. It is concluded, that in rodents induced lesions of the larynx differ in type, distribution pattern, severity and incidence from spontaneous lesions.     

能否像种蘑菇一样生产商品肉猪

在最近的10年中,现代猪种的生产性能已经得到了显著的提高,并且今后肯定将进一步提高。然而,猪生产性能的提高存在着一定的限度,因为尽管猪的遗传潜力得到了提高,但由于动物营养和保健技术进展缓慢使该潜力极少能够实现。