The effects of ammonium sulphate deposition and root sinks on soil solution chemistry in coniferous forest soils

The effects of enhanced (NH_{4 2}SO₄deposition on soil solution cation and anion concentrations and annualionic fluxes were followed using a standardised experimental protocolin six European coniferous forests with contrasting soil types, pollutioninputs and climate. Native soil cores containing a ceramic suction cupwere installed in the field, roofed and watered every two weeks withlocal throughfall or local throughfall with added(NH₄)₂SO₄ at 75 kgNH₄ ⁺-N ha^-1 a^-1. Livingroot systems were established in half of the lysimeters.Untreated throughfall NH₄ ⁺-N deposition at thesites ranged from 3.7 to 29 kg ha^-1 a^-1Soil leachates were collected at two weekly intervalsover 12 months and analysed for volume, andconcentrations of major anions and cations. Increasesin soil solution NO₃ ^- concentrations inresponse to N additions were observed after 4–9months at three sites, whilst one sandy soil with highC:N ratio failed to nitrify under any of thetreatments. Changes in NO₃ ^- concentrationsin soil solution controlled soil solution cationconcentrations in the five nitrifying soils, withAl³⁺ being the dominant cation in the more acidsoils with low base saturation. The acidification responses ofthe soils to the (NH_{4 2}SO₄additions were primarily related to the ability of thesoils to nitrify the added NH₄ ⁺. pH and soiltexture seemed important in controllingNH₄ ⁺ leaching in response to the treatments,with two less acidic, clay/clay loam sites showingalmost total retention of added NH₄ ⁺, whilstnearly 75% of the added N was leached asNH₄ ⁺ at the acid sandy soils. The presenceof living roots significantly reduced soil solutionNO₃ ^- and associated cation concentrations attwo of the six sites. The very different responses of the sixsoils to increased (NH₄)₂SO₄deposition emphasise that the establishment of N critical loadsfor forest soils need to allow for differences in N storagecapacity and nitrification potential.     

内蒙古西伯利亚棘球绦虫和多房棘球绦虫泡状蚴在小白鼠发育成熟的比较

本文报道人兽共患的泡状肝包虫病原,西伯利亚棘球绦虫Echinococcus sibiricensis (Rausch andSchiller, 1954)泡状蚴和多房棘球绦虫Ech inococcusmultilocularis ( Leuckart, 1863)泡状蚴在KM株小白鼠发育成熟过程比较观察的结果.此两虫种泡状蚴的发育成熟过程仍然和它们早期发育的规律(唐崇惕等,2001)相同.虽然它们成熟的泡囊都被着生在网状结构中的许多原头节所充满,但是在多房棘球绦虫9-14个月的泡状蚴,仍然可以见到它们的原头节和网状结构都是起源于泡囊囊壁内表面的胚细胞层,并且始终保持与该层的联系.而西伯利亚棘球绦虫泡状蚴在鼠肺脏或肝脏的各泡囊中的原头节和网状结构是由可移动的胚细胞团发育生成,它们与泡囊囊壁没有如前者样的联系.西伯利亚棘球泡状蚴在各别小白鼠肝脏也能发育成熟,但不正常,宿主反应异常强烈.     

Immunolocalisation of bilitranslocase in mucosecretory and parietal cells of the rat gastric mucosa

SummaryBilitranslocase is a plasma membrane carrier localised at the vascular pole of the rat liver cell, where it mediates uptake of organic anions from the blood into the liver. This carrier is also present in the epithelium of the rat gastric mucosa, with similar molecular mass and functional properties. An immunohistochemical study reveals that both the mucus-secreting cells of the gastric pit and the H⁺-secreting parietal cells express bilitranslocase. These data point to a possible role of bilitranslocase and of its food-borne substrates (anthocyanins and nicotinic acid) in regulating the function and the permeability of the gastric mucosa.     

Front Cover: Assessment of trans‐scleral iontophoresis delivery of lutein to the human retina (J. Biophotonics 3/2018)

Trans‐scleral iontophoresis device was shown to be effective for in‐situ delivery of lutein to the retina of human donor eyes. After treatment, Resonance Raman Spectroscopy measurements demonstrated that lutein greatly enriched the inner sclera, choroid and retina. Clinical studies are going to prove if the methodology would be a valuable approach to enrich the human macular pigment and prevent local oxidative damage in patients at risk of AMD progression. Further details can be found in the article by Marco Lombardo et al. ( e201700095 ).

     

Non‐invasive optical method for real‐time assessment of intracorneal riboflavin concentration and efficacy of corneal cross‐linking

Keratoconus is the primary cause of corneal transplantation in young adults worldwide. Riboflavin/UV‐A corneal cross‐linking may effectively halt the progression of keratoconus if an adequate amount of riboflavin enriches the corneal stroma and is photo‐oxidated by UV‐A light for generating additional cross‐linking bonds between stromal proteins and strengthening the biomechanics of the weakened cornea. Here we reported an UV‐A theranostic prototype device for performing corneal cross‐linking with the ability to assess corneal intrastromal concentration of riboflavin and to estimate treatment efficacy in real time. Seventeen human donor corneas were treated according to the conventional riboflavin/UV‐A corneal cross‐linking protocol. Ten of these tissues were probed with atomic force microscopy in order to correlate the intrastromal riboflavin concentration recorded during treatment with the increase in elastic modulus of the anterior corneal stroma. The intrastromal riboflavin concentration and its consumption during UV‐A irradiation of the cornea were highly significantly correlated (R = 0.79; P = .03) with the treatment‐induced stromal stiffening effect. The present study showed an ophthalmic device that provided an innovative, non‐invasive, real‐time monitoring solution for estimating corneal cross‐linking treatment efficacy on a personalized basis.      

A nonself recognition gene complex in Neurospora crassa

Nonself recognition is exemplified in the fungal kingdom by the regulation of cell fusion events between genetically different individuals (heterokaryosis). The het-6 locus is one of approximately 10 loci that control heterokaryon incompatibility during vegetative growth of N. crassa. Previously, it was found that het-6-associated incompatibility in Oak Ridge (OR) strains involves two contiguous genes, het-6 and un-24. The OR allele of either gene causes "strong" incompatibility (cell death) when transformed into Panama (PA)-background strains. Several remarkable features of the locus include the nature of these incompatibility genes (het-6 is a member of a repetitive gene family and un-24 also encodes the large subunit of ribonucleotide reductase) and the observation that un-24 and het-6 are in severe linkage disequilibrium. Here, we identify "weak" (slow, aberrant growth) incompatibility activities by un-24PA and het-6PA when transformed separately into OR strains, whereas together they exhibit an additive, strong effect. We synthesized strains with the new allelic combinations un-24PA het-6OR and un-24OR het-6PA, which are not found in nature. These strains grow normally and have distinct nonself recognition capabilities but may have reduced fitness. Comparing the Oak Ridge and Panama het-6 regions revealed a paracentric inversion, the architecture of which provides insights into the evolution of the un-24-het-6 gene complex.     

Dual mode of action of Bac7, a proline-rich antibacterial peptide

Proline-rich peptides are a unique group of antimicrobial peptides that exert their activity selectively against Gram-negative bacteria through an apparently non-membranolytic mode of action that is not yet well understood. We have investigated the mechanism underlying the antibacterial activity of the proline-rich cathelicidin Bac7 against Salmonella enterica and Escherichia coli. The killing and membrane permeabilization kinetics as well as the cellular localization were assessed for the fully active N-terminal fragment Bac7(1-35), its all-D enantiomer and for differentially active shortened fragments. At sub-micromolar concentrations, Bac7(1-35) rapidly killed bacteria by a non-lytic, energy-dependent mechanism, whereas its D-enantiomer was inactive. Furthermore, while the L-enantiomer was rapidly internalized into bacterial cells, the D-enantiomer was virtually excluded. At higher concentrations (>or=64 microM), both L- and D-Bac7(1-35) were instead able to kill bacteria also via a lytic mechanism. Overall, these results suggest that Bac7 may inactivate bacteria via two different modes of action depending on its concentration: (i) at near-MIC concentrations via a mechanism based on a stereospecificity-dependent uptake that is likely followed by its binding to an intracellular target, and (ii) at concentrations several times the MIC value, via a non-stereoselective, membranolytic mechanism.