Concretions in the human testis are derived from the basal lamina of seminiferous cords

Summary We provide evidence that testicular concretions form exclusively in association with seminiferous cords. Testicular material obtained from 6 patients with various disorders of spermatogenesis was studied by means of light-and electron microscopy. Seminiferous cords in the testes examined form so-called hypoplastic zones. They contain immature Sertoli cells and are surrounded by an unusually thick basal lamina and one or two layers of myofibroblasts. They display extensive coiling and form ring-like structures. Concretions are located at the periphery or in the center of the cords and consist of a hyaline material with an occasional granular core. They are enveloped by Sertoli cells or myofibroblasts. Data presented indicate that concretions may develop within the above-mentioned ring-like structures or in deep indentations of the surrounding connective tissue. Computer-assisted 3-D reconstructions of a seminiferous cord based on 24 serial semithin sections revealec that the majority of concretions communicate with the interstitial tissue through a broad opening comparable to a meso. On the basis of our observations we could demonstrate that concretions are accumulations of basal lamina that occasionally contain remnants of degenerated myofibroblasts. They form outside the cords and belong to the connective tissue compartment. As the components of the basal lamina are thought to be produced by the interaction of Sertoli cells and myofibroblasts we tentatively assume that the development of concretions reflects a disturbance in this complex interaction. We suggest that the presence of concretions refers to a developmental disorder and may be pathognomonic for the occurrence of defective seminiferous cords.Supported by Deutsche Forschungsgemeinschaft (Ho 388/6-1) and Verein zur Förderung der Forschung auf dem Gebiet der Fortpflanzung e.V; Hamburg     

β Cell-Specific Deletion of the IL-1 Receptor Antagonist Impairs β Cell Proliferation and Insulin Secretion

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Performance of two Picea abies (L.) Karst. stands at different stages of decline

Summary The development of root tips and apparent ectomycorrhizas was compared in the Fichtelgebirge (FRG) over one growing season in two 30-year-old Picea abies stands, both on soils derived from phyllite but showing varying symptoms of decline. Visual symptoms of tree decline reflected a lower relative and absolute mycorrhizal frequency, a lower number of ectomycorrhizas per m² leaf area and an uneven vertical distribution of root tips and ectomycorrhizas. The number of apparent ectomycorrhizas per ground area was correlated with the amount of magnesium, calcium, and ammonium, and the pH in the free-drainage soil solution, and with the molar calcium to aluminium ratio in mineral soil extracts. The foliage concentrations of magnesium and calcium were correlated with the numbers of apparent ectomycorrhizas per m² leaf or ground area. These observations were used to formulate testable hypotheses concerning the role of the root system and the soil environment in forest decline.     

Dysfunction of Arabidopsis MACPF domain protein activates programmed cell death via tryptophan metabolism in MAMP‐triggered immunity

Plant immune responses triggered upon recognition of microbe‐associated molecular patterns (MAMPs) typically restrict pathogen growth without a host cell death response. We isolated two Arabidopsis mutants, derived from accession Col‐0, that activated cell death upon inoculation with nonadapted fungal pathogens. Notably, the mutants triggered cell death also when treated with bacterial MAMPs such as flg22. Positional cloning identified NSL1 (Necrotic Spotted Lesion 1) as a responsible gene for the phenotype of the two mutants, whereas nsl1 mutations of the accession No‐0 resulted in necrotic lesion formation without pathogen inoculation. NSL1 encodes a protein of unknown function containing a putative membrane‐attack complex/perforin (MACPF) domain. The application of flg22 increased salicylic acid (SA) accumulation in the nsl1 plants derived from Col‐0, while depletion of isochorismate synthase 1 repressed flg22‐inducible lesion formation, indicating that elevated SA is needed for the cell death response. nsl1 plants of Col‐0 responded to flg22 treatment with an RBOHD‐dependent oxidative burst, but this response was dispensable for the nsl1‐dependent cell death. Surprisingly, loss‐of‐function mutations in PEN2, involved in the metabolism of tryptophan (Trp)‐derived indole glucosinolates, suppressed the flg22‐induced and nsl1‐dependent cell death. Moreover, the increased accumulation of SA in the nsl1 plants was abrogated by blocking Trp‐derived secondary metabolite biosynthesis, whereas the nsl1‐dependent hyperaccumulation of PEN2‐dependent compounds was unaffected when the SA biosynthesis pathway was blocked. Collectively, these findings suggest that MAMP‐triggered immunity activates a genetically programmed cell death in the absence of the functional MACPF domain protein NSL1 via Trp‐derived secondary metabolite‐mediated activation of the SA pathway.     

The expansion of short rotation forestry: characterization of determinants with an agent‐based land use model

Wood is a limited resource which is exposed to a continuously growing global demand not least because of a politically fostered bioenergy use. One approach to master the challenge to sustainably meet this increasing wood demand is short rotation forestry (SRF). However, SRF is only gradually evolving and it is not fully understood which determinants hamper its expansion. This study provides theoretical insights into economic and environmental determinants of an SRF expansion and their interplay. This assessment requires the incorporation of farmers' decision‐making based on an explicit investment appraisal. Therefore, we use an agent‐based model to depict the decision‐making of profit‐maximizing farmers facing the choice between SRF, the cultivation of conventional annual agricultural crops and abstaining from cultivation (fallow land). The land use decisions are influenced by general economic determinants, such as market prices for wood and annual crops, and by site‐dependent determinants, such as the environmental site quality. We found that the willingness to pay for SRF‐based products and for annual crops most strongly influences the coverage of SRF in the landscape. SRF will in most cases be established on sites with low productivity. However, a decrease in the willingness to pay for annual crops will lead to a reallocation of SRF plantations to sites with higher productivity. Furthermore, our model results indicate that the impact of the distance to processing plants on farmers' decisions strongly depends on general economic determinants and the given spatial structure of the underlying natural landscape. Analysing the relative importance of different determinants of an SRF expansion, this study gives insights into the approach of using SRF to sustainably meet the growing wood demand. Moreover, these insights are taken as a starting point for the design of effective government interventions to promote SRF.     

Thrombopoietin acts synergistically on Ca(2+) mobilization in platelets caused by ADP or thrombin receptor agonist peptide.

Thrombopoietin (TPO) is the main regulator of megakaryopoiesis and influences also the function of mature platelets. TPO has been shown to synergize in multiple platelet activation processes induced by various agonists. Our aim was to elucidate whether TPO affects calcium signaling during platelet activation processes. TPO demonstrated a synergistic effect on the exocytosis induced by suboptimal doses of adenosine diphosphate (ADP) and the thrombin receptor agonist peptide (TRAP). We detected synergistic effects of TPO on the ADP or TRAP induced Ca(2+) mobilization in a small range of very low agonist concentrations. The TPO synergism on Ca(2+) mobilization and CD62P expression was measurable in different, nonoverlapping ranges of ADP or TRAP concentrations. Sustaining the agonist-induced calcium signal with thapsigargin led to a detectable TPO synergism in CD62P expression even in agonist concentrations in which the synergism only occurs in Ca(2+) signaling without thapsigargin.     

Beiträge zur Pollenmorphologie der Iridaceae und ihre Bedeutung für die Taxonomie

Fifty-five genera of the Iridaceae were pollen morphologically investigated. The particularities stated in the apertures as well as the structure and sculpture of the exine are useful characteristics for the taxonomy of the family. On the base of the results of pollen morphological investigations and considering numerous further characteristics, a new arrangement of the Iridaceae is proposed.