Food web manipulation in Lake Zwemlust: Positive and negative effects during the first two years

The hypertrophic Lake Zwemlust, a small water body used as a swimming pool, was characterized by algal blooms in summer, reducing the Secchi disk transparency to less than 0.3 m. Since in The Netherlands a Secchi disk transparency of 1 m is obligatory for swimming waters, corrective measures were called for to improve the light climate of the lake. In March, 1987, as an experiment, the lake was drained by pumping out the water to facilitate fish elimination. Planktivorous and benthivorous fish species, which were predominant, were removed by seine- and electro-fishing. After the lake had refilled by seepage it was restocked by a new simple fish community comprising pike (Esox lucius) and rudd (Scardinius erythrophthalmus) only. Stacks of willow twigs (Salix) and macrophytes (roots ofNuphar lutea and seedlings ofChara globularis) were introduced into the lake as spawning grounds and refuges for the pike against cannibalism and as shelter for the zooplankton. The effects of this food web manipulation on the light climate, phytoplankton, zooplankton, fish, macrophytes, macrofauna and on the nutrient concentrations were monitored during 1987 and 1988. In summer 1987, despite of high nutrient concentrations, the phytoplankton density was low, due to control by zooplankton, causing a Secchi disk transparency of 2.5 m, the maximum depth. Chlorophyll-a concentrations were low (<5 g Chl.l^–1), blooms of cyanobacteria did not occur and a shift from rotifers to cladocerans took place. In 1988, however, also some negative effects were noticed. Macrophytes and filamentous green algae reached a much higher biomass (50–60% cover of the lake bottom) than in 1987; some species, growing through the entire water column, interfered with the lake's recreational use. Associated with the macro-vegetation and possibly with the absence of larger cyprinids, the diet of which also comprises snails, a large scale development of the snail population, among themLymnaea peregra var.ovata took place. This species is known to act as an intermediate host of the bird-parasitizing trematodeTrichobilharzia ocellata, the cercariae of which cause an itching sensation at the spot of penetration of the human skin, accompanied by rash (schistosome dermatitis or swimmers' itch); in July, 1988, about 40% of the bathers complained about this itching. A positive effect of the macrophytes and filamentous green algae was the high uptake of nitrogen, resulting in a low nitrogen concentration in the lake and growth limitation of the phytoplankton population by nitrogen in the summer of 1988. In 1988 the cladocerans were abundant in April only; and unlike in 1987, in the summer of 1988 there was a shift from cladocerans to rotifers. Therefore, only in early spring (April) zooplankton grazing controlled phytoplankton growth and in summer nitrogen limitation was the major controlling factor, keeping chlorophyll-a concentrations low.     

Analysis of Fusarium causing dermal toxicosis in marram grass planters

In the European coastal dunes, marram grass (Ammophila arenaria) is planted in order to control sand erosion. In the years 1986 to 1991, workers on the Wadden islands in the Netherlands planting marram grass showed lesions of skin and mucous membranes, suggesting a toxic reaction. Fusarium culmorum dominated the mycoflora of those marram grass culms that were used for planting. This plant material had been cut and stored for more than one week in the open. The Fusarium toxin deoxynivalenol (DON) was detected in the suspect marram grass culms. Isolated F. culmorum strains were able to produce DON in vitro in liquid culture as well as in experimentally inoculated wheat heads. Pathogenicity tests, toxin test as well as RAPD analysis showed that the F. culmorum strains were not specialized for marram grass but may form part of the West-European F. culmorum population infecting cereals and grasses. Storage on old sand-dunes with plant debris may have led to the high occurrence of F. culmorum and contamination with DON. Marram grass culms should be obtained from young plantings on dunes on the seaward slopes and cut culms should not be stored.     

Mouse genetics identifies unique and overlapping functions of fibroblast growth factor receptors in keratinocytes

Fibroblast growth factors (FGFs) are key regulators of tissue development, homeostasis and repair, and abnormal FGF signalling is associated with various human diseases. In human and murine epidermis, FGF receptor 3 (FGFR3) activation causes benign skin tumours, but the consequences of FGFR3 deficiency in this tissue have not been determined. Here, we show that FGFR3 in keratinocytes is dispensable for mouse skin development, homeostasis and wound repair. However, the defect in the epidermal barrier and the resulting inflammatory skin disease that develops in mice lacking FGFR1 and FGFR2 in keratinocytes were further aggravated upon additional loss of FGFR3. This caused fibroblast activation and fibrosis in the FGFR1/FGFR2 double‐knockout mice and even more in mice lacking all three FGFRs, revealing functional redundancy of FGFR3 with FGFR1 and FGFR2 for maintaining the epidermal barrier. Taken together, our study demonstrates that FGFR1, FGFR2 and FGFR3 act together to maintain epidermal integrity and cutaneous homeostasis, with FGFR2 being the dominant receptor.     

A possible case of necrotizing dermatitis in the crocodylian Diplocynodon,from the Oligocene of the Isle of Wight,United Kingdom

Here we describe a pathological osteoderm from the crocodylomorph Diplocynodon hantoniensis (Bouldnor Formation, earliest Oligocene, Isle of Wight, United Kingdom). The specimen bears a porous, erosive branching channel that distorts the surface ornamentation and periosteum over 60% of the preserved dorsal surface area. We diagnose this condition as necrotizing dermatitis: a surficial bacterial or fungal infection that can penetrate the dermal layers to affect the underlaying penosteum of osteoderms. This condition has been previously reported for an extant tortoise and caiman; however, this is the first reported occurrence in the fossil record.     

The inhibitory effect of naringenin on atopic dermatitis induced by DNFB in NC/Nga mice

Aims

Atopic dermatitis (AD) is a chronic and relapsing inflammatory dermatitis characterized by pruritic and eczematous skin lesions. Here, we investigated the therapeutic effect of the fruit flavonoid naringenin on DNFB induced atopic dermatitis mice model.

Main methods

AD-like skin lesion was induced by repetitive skin contact with DNFB in NC/Nga mice and the effects of the fruit flavonoid naringenin were evaluated on the basis of histopathological findings of skin, ear swelling and cytokine production of CD4⁺T cells.

Key findings

Intraperitoneal injection of naringenin for one week after DNFB challenge significantly lowered ear swelling and improved back skin lesions. In addition, naringenin significantly suppressed production of interferon-gamma (IFN-γ) by activated CD4⁺ T cells and serum IgE level. Furthermore, naringenin reduced DNFB-induced infiltration of eosinophils, mast cells, CD4⁺ T cells, and CD8⁺ T cells in skin lesions.

Significance

Naringenin may suppress the development of AD-like skin lesions in DNFB-treated NC/Nga mice by reducing IFN-γ production of activated CD4⁺ T cells, serum IgE levels and infiltration of immune cells to skin lesion.     

α-l-Rhamnosidase Activity in Culture Filtrate of Corticium rolfsii Enzymic Activity at Low pH

A phosphorylation system for formation of ATP from AMP by Zymolyase-treated cells of Candida boidinii (Kloeckera sp.) No. 2201 was developed as an ATP production process. This system was shown to be an energy conversion system, from a reduced C₁ -compound to ATP through reduction of NAD⁺ and oxidative phosphorylation but not substrate level phosphorylation, together with phosphorylation of AMP to ADP.

Reaction conditions for the ATP production were optimized in respect of substrate and coenzyme concentrations, pH and temperature, osmotic pressure, and oxygen supply. Under the optimal conditions, 26 mM (13 g/liter) and 8.5 dim (4g/liter) of ATP were produced with methanol and formate as C₁ -substrate, respectively.     

Classification of established atopic dermatitis in children with the in vivo imaging methods

Atopic dermatitis (AD) is a cutaneous disease resulting from a defective barrier and dysregulated immune response. The severity scoring of atopic dermatitis (SCORAD) is used to classify AD. Noninvasive imaging approaches supplementary to SCORAD were investigated. Cr:forsterite laser‐based microscopy was employed to analyze endogenous third‐harmonic generation (THG) and second‐harmonic generation (SHG) signals from skin. Imaging parameters were compared between different AD severities. Three‐dimensional reconstruction of imaged skin layers was performed. Finally, statistic models from quantitative imaging parameters were developed for predicting disease severity. Our data demonstrate that THG signal intensity of lesional skin in AD were significantly increased and was positively correlated with AD severity. Characteristic gray level co‐occurrence matrix (GLCM) values were observed in more severe AD. In the 3D reconstruction video, individual dermal papilla and obvious fibrosis in the upper papillary dermis were easily identified. Our estimation models could predict the disease severity of AD patients with an accuracy of nearly 85%. The THG signal intensity and characteristic GLCM patterns are associated with AD severity and can serve as quantitative predictive parameters. Our imaging approach can be used to identify the histopathological changes of AD objectively, and to complement the SCORAD index, thus improving the accuracy of classifying AD severity.      

黄芪多糖对咪喹莫特诱导小鼠银屑病样皮炎的干预作用及其机制*

目的: 探讨黄芪多糖对咪喹莫特诱导的小鼠银屑病样皮炎的干预作用及其机制。方法: 40只健康雌性C57BL/6小鼠随机分为空白对照组、模型组、黄芪多糖高剂量组(200 mg/kg)、中剂量组(100 mg/kg)和低剂量组(50 mg/kg),共5组,每组8只,利用5%咪喹莫特乳膏涂抹小鼠背部制备银屑病样皮炎模型,监测各组小鼠PASI评分,并采用ELISA测定小鼠炎症因子分泌的变化,通过流式细胞术检测皮炎中巨噬细胞的浸润程度。结果: 与空白对照组比较,模型组小鼠PASI评分明显增加(P＜0.05),血清TNF-α、IL-1β和IL-6水平明显升高(P＜0.05),皮肤组织中浸润的巨噬细胞明显增加(P＜0.05);与模型组比较,黄芪多糖高、中剂量组小鼠PASI评分明显明显减少(P＜0.05),小鼠血清TNF-α、IL-1β和IL-6水平明显下调(P＜0.05);黄芪多糖高剂量组小鼠皮肤组织中浸润的巨噬细胞明显减少(P＜0.05)。结论: 黄芪多糖通过抑制皮肤组织中巨噬细胞浸润,降低血清中TNF-α、IL-1β和IL-6的分泌,来改善小鼠银屑病样皮炎。     

Identification of Staphylococcus xylosus isolated from C57BL/6J-Nos2(tm1Lau) mice with dermatitis

Coagulase negative staphylococci (CNS) are significant pathogens, particularly in medical device related infections and in immunocompromised patients. Five CNS strains were isolated from 5 NOS2 knockout mice with dermatitis. Histologically, granulomatous dermatitis was found in the skin around the ear with epidermal ulceration. Dermal lesions included pustules, necrosis, and accumulations of neutrophils and macrophages. Isolates of the bacterial strains were identified to be Staphylococcus xylosus by the API STAPH kit and 16S-23S intergenic transcribed spacer-PCR. These results demonstrate the potential of this organism to be an opportunistic pathogen in immunocompromised mice.