Changes in phosphorus concentrations in a eutrophic lake as a result of macrophyte-kill following herbicide application

Phosphorus (P) concentrations in water and sediment of a highly eutrophic lake were monitored before and after application of diquat to control the macrophyte Potamogeton crispus. Only a relatively small and short-term increase in P concentration in water occurred shortly after plant die-off resulting from herbicide application. Phosphorus concentrations in shallow water sediments decreased during the summer, and those in deep water sediments increased. Although a large increase in P concentration in the water occurred in late summer, it was not attributed to diquat. No major secondary effects of herbicide application were found during this study.     

Three-dimensional models of chick embryo somites obtained by mathematical methods applied to ultrastructural data

Summary A model of a thoracolumbar somite of a chick embryo at the 53rd incubation hour was obtained by mathematical methods, after identification of somite cell types by means of electron microscopy.Each specific district occupied by the cell types was precisely determined.On the basis of these observations, the somite was three-dimensionally reconstructed and the spatial positions of the primitive myotome, dermatome, sclerotome, undifferentiated mesoderm and myocele were precisely identified.     

On the fungitoxicity of some new thiocyanatopyrazole derivatives: Electron microscopical study in trichophyton mentagrophytes

Four thiocyanatopyrazole derivatives were synthesized and their fungistatic activity was demonstrated in vitro against a number of dermatophytic fungi. In Trichophyton mentagrophytes, the most active compound induced an unusual increase of the plasma membrane with production of intra and extracytoplasmic complexes, a deterioration of nuclear and mitochondrial membranes and a formation of autophagic-like vacuoles. Plasmolysis, accompanied by an almost complete disorganization of cytoplasmic structures, seemed to be the final event. A possible mechanism of action of the compounds was discussed.Investigation supported by a grant from Consiglio Nazionale delle Ricerche of Italy (Contract No. 7500536).     

Fluorogenic detection of primary amines in plant histochemistry with fluorescamine: A comparative study on the effects of coagulant and non-coagulant fixatives

Summary The new highly sensitive method of fluorescamine reaction for the topochemical detection of primary amino groups was studied as a substitude of ninhydrin-Schiff's reaction for the localisation of total proteins in plant tissues. The influence of various coagulant and non-coagulatn fixatives on the induction of fluorescamine fluorescence was examined: ethanol, formaldehyde gas and solution, glutaraldehyde, acrolein, osmium tetroxide, Bouin, Rossman, Clarke and Zenker's fluids and FMA were employed. It was found that the use of the fluorogenic method is conditioned by the fixative ability to keep the amino groups disposable and by its capability to reduce the natural autofluorescence of plant material. A detailed account of the fixation methodology demonstrated that non-coagulant acrolein and coagulant mercuric chloride are the most promising fixatives for the use of the fluorescamine reaction in plant histochemistry.     

Glycoalkaloid Profile in Potato Haploids Derived from Solanum tuberosum–S. bulbocastanum Somatic Hybrids

Cultivated and wild potato species synthesize a wide variety of steroidal glycoalkaloids (GA) that may affect either human health or biotic stress resistance. Therefore, GA composition must be a major criterion in the evaluation of breeding products when species genomes are merged and/or manipulated. This work reports the results of GA analysis performed on unique haploid (2n=2x=24) plants obtained from tetraploid (2n=4x=48) Solanum bulbocastanum–S. tuberosum hybrids through in vitro anther culture. Glycoalkaloids were extracted from tubers and analyzed by HPLC. Haploids generally showed the occurrence of parental GA. However, in several cases loss of parental GA and gain of new GA lacking in the parents was observed. It may be hypothesized that new GA profiles of our haploids is the result of either genetic recombination or combinatorial biochemistry events. To highlight differences between haploids and parents, soluble proteins and antioxidant activities were also determined. Both were always higher in haploids compared to their parents. The nature of the newly formed GAs will be further investigated, because they may represent new metabolites that can be used against pest and diseases, or are useful for human health.     

Autophagy inhibition radiosensitizes in vitro,yet reduces radioresponses in vivo due to deficient immunogenic signalling

Clinical oncology heavily relies on the use of radiotherapy, which often leads to merely transient responses that are followed by local or distant relapse. The molecular mechanisms explaining radioresistance are largely elusive. Here, we identified a dual role of autophagy in the response of cancer cells to ionizing radiation. On one hand, we observed that the depletion of essential autophagy-relevant gene products, such as ATG5 and Beclin 1, increased the sensitivity of human or mouse cancer cell lines to irradiation, both in vitro (where autophagy inhibition increased radiation-induced cell death and decreased clonogenic survival) and in vivo, after transplantation of the cell lines into immunodeficient mice (where autophagy inhibition potentiated the tumour growth-inhibitory effect of radiotherapy). On the other hand, when tumour proficient or deficient for autophagy were implanted in immunocompetent mice, it turned out that defective autophagy reduced the efficacy of radiotherapy. Indeed, radiotherapy elicited an anti-cancer immune response that was dependent on autophagy-induced ATP release from stressed or dying tumour cells and was characterized by dense lymphocyte infiltration of the tumour bed. Intratumoural injection of an ecto-ATPase inhibitor restored the immune infiltration of autophagy-deficient tumours post radiotherapy and improved the growth-inhibitory effect of ionizing irradiation. Altogether, our results reveal that beyond its cytoprotective function, autophagy confers immunogenic properties to tumours, hence amplifying the efficacy of radiotherapy in an immunocompetent context. This has far-reaching implications for the development of pharmacological radiosensitizers.     

Modulation of aldosterone receptors in rat kidney: effects of steroid treatment and potassium diet

The numbers of type I and type II aldosterone receptors in the kidney cytosol of adrenalectomized rats were estimated after animals were treated with various steroids, or fed with high or low potassium diets. Oestradiol and 5 beta-pregnane-3,20 dione, which exhibited no affinity for aldosterone receptors, did not modify the levels of type I or type II receptors. Cortisol, corticosterone, progesterone and spirolactones, which all competed with aldosterone for both types of receptor, reduced the number of type I sites, as does aldosterone itself. Steroid treatment has no appreciable effect on type II receptors. We conclude that type I receptors are modulated by steroids able to bind to aldosterone receptors and that steroid-receptor interaction is an essential step in the receptor modulation process. The effects of potassium on aldosterone receptor modulation were tested in adrenalectomized rats on hypo- or hyperkalaemic diets. No change in receptor levels was observed in the rats on a low potassium diet, but the number of type I receptors increased in animals on a high potassium diet. However, the effects of potassium on receptor modulation were of lesser magnitude than those of aldosterone agonists and antagonists.     

Effects of 50 Hz magnetic fields on mouse spermatogenesis monitored by flow cytometric analysis

Flow cytometry (FCM) was performed to monitor the cellular effects of extremely-low-frequency magnetic field on mouse spermatogenesis. Groups of five male hybrid F1 mice aged 8–10 weeks were exposed to 50 Hz magnetic field. The strength of the magnetic field was 1.7 mT. Exposure times of 2 and 4 h were chosen. FCM measurements were performed 7, 14, 21, 28, 35, and 42 days after treatment. For each experimental point, a sham-treated group was used as a control. The possible effects were studied by analyzing the DNA content distribution of the different cell types involved in spermatogenesis and using the elongated spermatids as the reference population. The relative frequencies of the various testicular cell types were calculated using specific software. In groups exposed for 2 h, no effects were observed. In groups exposed for 4 h, a statistically significant (P < 0.001) decrease in elongated spermatids was observed at 28 days after treatment. This change suggests a possible cytotoxic and/or cytostatic effect on differentiating spermatogonia. However, further studies are being carried out to investigate the effects of longer exposure times. © 1995 Wiley-Liss, Inc.     

Tissue-selective regulation of protein homeostasis and unfolded protein response signalling in sporadic ALS

Amyotrophic lateral sclerosis (ALS) is a disorder that affects motor neurons in motor cortex and spinal cord, and the degeneration of both neuronal populations is a critical feature of the disease. Abnormalities in protein homeostasis (proteostasis) are well established in ALS. However, they have been investigated mostly in spinal cord but less so in motor cortex. Herein, we monitored the unfolded protein (UPR) and heat shock response (HSR), two major proteostasis regulatory pathways, in human post-mortem tissue derived from the motor cortex of sporadic ALS (SALS) and compared them to those occurring in spinal cord. Although the UPR was activated in both tissues, specific expression of select UPR target genes, such as PDIs, was observed in motor cortex of SALS cases strongly correlating with oligodendrocyte markers. Moreover, we found that endoplasmic reticulum-associated degradation (ERAD) and HSR genes, which were activated predominately in spinal cord, correlated with the expression of neuronal markers. Our results indicate that proteostasis is strongly and selectively activated in SALS motor cortex and spinal cord where subsets of these genes are associated with specific cell type. This study expands our understanding of convergent molecular mechanisms occurring in motor cortex and spinal cord and highlights cell type–specific contributions.     

Global emergence of environmental non-O1/O139 Vibrio cholerae infections linked with climate change: a neglected research field?

The bacterium Vibrio cholerae is a natural inhabitant of aquatic ecosystems across the planet. V. cholerae serogroups O1 and O139 are responsible for cholera outbreaks in developing countries accounting for 3–5 million infections worldwide and 28.800–130.000 deaths per year according to the World Health Organization. In contrast, V. cholerae serogroups other than O1 and O139, also designated as V. cholerae non-O1/O139 (NOVC), are not associated with epidemic cholera but can cause other illnesses that may range in severity from mild (e.g. gastroenteritis, otitis, etc.) to life-threatening (e.g. necrotizing fasciitis). Although generally neglected, NOVC-related infections are on the rise and represent one of the most striking examples of emerging human diseases linked to climate change. NOVC strains are also believed to potentially contribute to the emergence of new pathogenic strains including strains with epidemic potential as a direct consequence of genetic exchange mechanisms such as horizontal gene transfer and genetic recombination. Besides general features concerning the biology and ecology of NOVC strains and their associated diseases, this review aims to highlight the most relevant aspects related to the emergence and potential threat posed by NOVC strains under a rapidly changing environmental and climatic scenario.