Comparative studies on the structure of an upland African stream ecosystem

Upland stream systems have been extensively investigated in Europe, North America and Australasia and many of the central ideas concerning their function are based on these systems. One central paradigm, the river continuum concept is ultimately derived from those North American streams whose catchments remain forested with native vegetation. Streams of the tropics may or may not fit the model. They have been little studied. The Amani Nature Reserve in the East Usambara Mountains of north-eastern Tanzania offers an opportunity to bring these naturally forested systems to the attention of the ecological community. This article describes a comparison made between two lengths of the River Dodwe in this area. The work was carried out by a group of postgraduate students from eighteen European and African countries with advice from five staff members, as part of a course organised by the Tropical Biology Association. Rigorous efforts were made to standardise techniques, in a situation where equipment and laboratory facilities were very basic, through a management structure and deliberate allocation of work to specialists in each area.The article offers a summary of invertebrate communities found in the stream and its biomass. Crabs seem to be the key organism in both sections of the streams

Niclosamide Prevents the Formation of Large Ubiquitin-Containing Aggregates Caused by Proteasome Inhibition

Protein aggregation is a hallmark of many neurodegenerative diseases and has been linked to the failure to degrade misfolded and damaged proteins. In the cell, aberrant proteins are degraded by the ubiquitin proteasome system that mainly targets short-lived proteins, or by the lysosomes that mostly clear long-lived and poorly soluble proteins. Both systems are interconnected and, in some instances, autophagy can redirect proteasome substrates to the lysosomes.To better understand the interplay between these two systems, we established a neuroblastoma cell population stably expressing the GFP-ubiquitin fusion protein. We show that inhibition of the proteasome leads to the formation of large ubiquitin-containing inclusions accompanied by lower solubility of the ubiquitin conjugates. Strikingly, the formation of the ubiquitin-containing aggregates does not require ectopic expression of disease-specific proteins. Moreover, formation of these focused inclusions caused by proteasome inhibition requires the lysine 63 (K63) of ubiquitin. We then assessed selected compounds that stimulate autophagy and found that the antihelmintic chemical niclosamide prevents large aggregate formation induced by proteasome inhibition, while the prototypical mTORC1 inhibitor rapamycin had no apparent effect. Niclosamide also precludes the accumulation of poly-ubiquitinated proteins and of p62 upon proteasome inhibition. Moreover, niclosamide induces a change in lysosome distribution in the cell that, in the absence of proteasome activity, may favor the uptake into lysosomes of ubiquitinated proteins before they form large aggregates.Our results indicate that proteasome inhibition provokes the formation of large ubiquitin containing aggregates in tissue culture cells, even in the absence of disease specific proteins. Furthermore our study suggests that the autophagy-inducing compound niclosamide may promote the selective clearance of ubiquitinated proteins in the absence of proteasome activity

MYB suppresses differentiation and apoptosis of human breast cancer cells

Introduction: MYB is highly expressed in estrogen receptor positive (ER + ve) breast tumours and tumour cell lines. We recently demonstrated that MYB is essential for the proliferation of ER + ve breast cancer cells, and have now investigated its role in mammary epithelial differentiation.Methods: MCF-7 breast cancer cells were treated with sodium butyrate, vitamin E succinate or 12-O-tetradecanoylphorbol-13-acetate to induce differentiation as measured by Nile Red staining of lipid droplets and β-casein expression. The non-tumorigenic murine mammary epithelial cell (MEC) line, HC11, was induced to differentiate with lactogenic hormones. MYB levels were manipulated by inducible lentiviral shRNA-mediated knockdown and retroviral overexpression.Results: We found that MYB expression decreases following chemically-induced differentiation of the human breast cancer cell line MCF-7, and hormonally-induced differentiation of a non-tumorigenic murine mammary epithelial cell (MEC) line, HC11. We also found that shRNA-mediated MYB knockdown initiated differentiation of breast cancer cells, and greatly sensitised them to the differentiative and pro-apoptotic effects of differentiation-inducing agents (DIAs). Sensitisation to the pro-apoptotic effects DIAs is mediated by decreased expression of BCL2, which we show here is a direct MYB target in breast cancer cells. Conversely, enforced expression of MYB resulted in the cells remaining in an undifferentiated state, with concomitant suppression of apoptosis, in the presence of DIAs.Conclusions: Taken together, these data imply that MYB function is critical in regulating the balance between proliferation, differentiation, and apoptosis in MECs. Moreover, our findings suggest MYB may be a viable therapeutic target in breast cancer and suggest specific approaches for exploiting this possibility

Small noncoding differentially methylated copy-number variants, including lncRNA genes, cause a lethal lung developmental disorder

An unanticipated and tremendous amount of the noncoding sequence of the human genome is transcribed. Long noncoding RNAs (lncRNAs) constitute a significant fraction of non-protein-coding transcripts; however, their functions remain enigmatic. We demonstrate that deletions of a small noncoding differentially methylated region at 16q24.1, including lncRNA genes, cause a lethal lung developmental disorder, alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV), with parent-of-origin effects. We identify overlapping deletions 250 kb upstream of FOXF1 in nine patients with ACD/MPV that arose de novo specifically on the maternally inherited chromosome and delete lung-specific lncRNA genes. These deletions define a distant cis-regulatory region that harbors, besides lncRNA genes, also a differentially methylated CpG island, binds GLI2 depending on the methylation status of this CpG island, and physically interacts with and up-regulates the FOXF1 promoter. We suggest that lung-transcribed 16q24.1 lncRNAs may contribute to long-range regulation of FOXF1 by GLI2 and other transcription factors. Perturbation of lncRNA-mediated chromatin interactions may, in general, be responsible for position effect phenomena and potentially cause many disorders of human development

Comparative studies on the structure of an upland African stream ecosystem

Upland stream systems have been extensively investigated in Europe,North America and Australasia and many of the central ideas concerningtheir function are based on these systems. One central paradigm, the rivercontinuum concept (Vannote et al. 1980) is ultimately derived from thoseNorth American streams whose catchments remain forested with nativevegetation

Bees substitute birds in pollination of ornitogamous climber Campsis radicans [L.] Seem. in Poland

Campsis radicans is an attractive climber with typical ornitogamous flowers, native to North America. In natural conditions this out-crossed plant is pollinated mostly by hummingbirds. In Poland, where C. radicans is cultivated as ornamental, it rarely sets seeds. The questions addressed in the present study were: (1) What animals pollinate its flowers in Poland?, and (2) What is the reason for infrequent fruit set? Field studies conducted in five localities in Poland showed that the principal pollinator is Apis mellifera, and the lack of seeds is usually caused by pollinator limitation or absence of genetically different pollen donor plants

The properties and utilization of proteases of marine fish and invertebrates

The muscles and internal organs of marine animals contain many proteases. These enzymes fulfill different metabolic functions in the living organisms and affect the sensory quality and functional properties of the catch. Their activity depends on the species, life cycle, and the feeding status of the organism. Many proteases of marine origin differ from their counterparts in terrestrial animals in being more active at lower temperature and less resistant to thermal denaturation. Of practical importance in the industry is their role in ripening of salted fish, fish sauces and marinades, modyfying fish protein concentrates, ensilaging of seafood offal, and deskinning of fishery products. The negative effects comprise mainly the early post morten quality degradation of the catch and deterioration of the rheological properties of fish gels. Proteolytic preparations form different marine sources may be used successfully in food processing and as industrial enzymes, e. g. tanning agents

Muscle cathepsins of marine fish and invertebrates

Muscle proteases are located mainly in the lysosomes, in the sarcoplasm, and in the extracellular matrix of the connective tissue surrounding each cell. The lysosomal proteases, cathepsins, have optimum activity in the acidic range, although many of them retain high activity also 1 or 2 pH units away from the optimum value. Among the cathepsins there are endopeptidases and exopeptidases. Most cathepsins hydrolyse several proteins of the myofibrils. The major protease of the lysosomes in fish and squid muscles is cathepsin D, an aspartyl endoproteinase. Although it is present in the muscle fibre itself, its generally rather low activity at low temperature limits its significance in tenderization of refrigerated fish of most species. Cathepsin L, a cysteinyl protease, is involved in autolysis and softening in matured chum salmon. Cathepsin B, a cysteinyl carboxypeptidase, is capable to attack also some myofibrillar proteins. Cathepsin A or carboxypeptidase A, and cathepsin C, a dipeptidyl hydrolase and dipeptidyl transferase, contribute to the hydrolysis of muscle proteins in a concerted action with the other cathepsins

Proteolityczna aktywnosc wnetrznosci i czesciowe oczyszczenie kwasnych proteaz z watrobo-trzustki kalmarow Illex argentinus

The squid hepatopancreas, containing 20-60% lipids, is not suitable on board vessel for producing fodder meal and is often discarded, although it constitutes the major part of the viscera and is a rich source of proteolytic enzymes. The proteolytic activity against hemoglobin at pH 3.0 of the extract of the he pato pan ere a s of frozen stored squid, calculated per mg of protein, is about 20 times higher than that of the extract of the rest of the viscera. Due to incubation of the homogenate at pH 3.0 at 30 and 40°C in 2 days a clear watery phase was formed, well separated from the oily fraction containing floating solid particles of the autolysate. In 2 days about 35 and 50% of the protein was hydrolysed at 20°C and 30-40°C, respectively, to degradation products not precipitated by TCA. The proteolytic activity of the autolyzed homogenate after 2 days at pH 3.0 is about 80 % of that of the original homogenate. Incubation at 40°C at pH 3.0 decreased the activity after 6 days by about 50%. In the autolysate of squid hepatopancreas the proteolytic activity at pH 3.0 in the absence of reducing compounds was almost totally due to aspartic proteases. In the presence of dithiothreitol the activity increased by about 50%, but the increase was only partly due to the presence of thiol proteases.Zbadano aktywność proteolityczną ekstraktów enzymów z wnętrzności mrożonych kalmarów Illex argentinus wobec hemoglobiny przy pH 3 oraz określono wpływ temperatury i czasu inkubacji na stabilność enzymów i autolizę białek homogenatu z wątrobo-trzustki. Proteolityczna aktywność przy pH 3 ekstraktu enzymów z wątrobo-trzustki kalmarów jest w przeliczeniu na 1 mg białek około 20 razy większa niż aktywność ekstraktów z pozostałych wnętrzności. Po dwóch dniach inkubacji homogenatu z wątrobo-trzustki w temperaturze 20°C i 30—40°C hydrolizuje odpowiednio około 35% i 50% białek. Proteolityczna aktywność w zautolizowanym homogenacie obniża się w tych warunkach o około 20%. Aktywność proteolityczna w autolizacie wykazywana przy pH 3 w nieobecności substancji redukujących pochodzi nieomal całkowicie od proteaz asparaginowych. Autoliza białek wątrobo-trzustki kalmarów jest prostą i tanią drogą uzyskiwania częściowo oczyszczonego preparatu enzymów proteolitycznych aktywnych w kwaśnym środowisku. Jednocześnie ułatwia ona oddzielenie lipidów i części stałych od klarownego autolizatu. Autolizat może stanowić półprodukt do otrzymywania preparatu enzymów proteolitycznych o większej czystości