Status of the harbour porpoise in Greenland

In Greenlandic waters the harbour porpoise (Phocoena phocoena) has been observed around the southern part of Greenland from Ammassalik on the east coast to Avanersuaq in northwest Greenland. The main distribution lies between Sisimiut and Paamiut in central west Greenland. Catch statistics from 1900 to 1993 indicate an annual average take of 668 harbour porpoises, ranging from 27 to 1531 animals. A decline in the reported catch has been recorded since 1980. Harbour porpoises are mainly caught between April and November, with a peak during June to October. Five fish species, crustaceans and squids have been found in stomach contents of harbour porpoises in Greenlandic waters. There are no indications that environmental issues such as organochlorines, heavy metals, oil or noise have constituted any threat to harbour porpoises in Greenland. No reports of ice entrapments of harbour porpoises have yet been made in Greenland, as is the case for white whales and narwhals on the west coast of Greenland. Disease patterns of harbour porpoise have not been studied in Greenland and incidents of mass mortality have never been recorded. Killer whales are sparse along the west Greenland coast and are not believed to constitute a threat to the harbour porpoise population. In Greenland no estimates on stock size are available, and a monitoring programme is needed if the impact of the catch is to be evaluated. Received: 10 February 1997 / Accepted: 26 September 1997     

Biodegradation and appearance of plastic treated solid wood

The biodegradation of plastics and wood with different susceptibility to fungal attack have in this study been compared in order to show the biodegradability in relation to the properties of plastic and solid wood. Wood blocks of Scots pine and English Oak were treated with biodegradable aliphatic polyester, polycaprolactone, and a non-biodegradable aromatic thermoplastic, polystyrene. The plastics were applied to the wood samples dissolved in an organic solvent and thereafter the treated wood samples were exposed to brown rot decay (Postia placenta) in an agar plate test for 8 weeks. The polycaprolactone treatments did not result in wood protection, whereas polystyrene treatments provided a protection from fungal attack. Both plastics are transparent and after treatment the solid wood blocks retained their natural wood appearance with a somewhat darker shinier surface.

Scientific relevance

Usually commercial wood-plastic composites are made using wood derived lignocellulose-fibers melt-blended in a screw extruder with a plastic matrix, and then the resulting material is mainly a plastic (in terms of properties and appearance) which contain some lignocellulose. We have instead used solid wood to which we have added transparent plastics, which preserve the unique and precious esthetic value of natural wood. This study describes the biodegradation of two (a more and a less resistant) wood species in combination with a biodegradable and a non-biodegradable plastic. The purpose was to study any synergetic effect in the biodegradation property between solid wood and plastic since there is a socio-environmental desire to use biodegradable plastics of renewable raw material for e.g. composite material. We show that both the wood and the plastic influence the biodegradation, for example by using an easily degraded European wood specie in combination with a biodegradable plastic (polycarolactone) no protection of the wood is obtained, whereas a relative small amount recalcitrant plastic (polystyrene) can somewhat protect both Scots pine and Oak wood without significantly compromising their appearance.     

Simulating uterine contraction by using an electro-chemo-mechanical model

Contractions of uterine smooth muscle cells consist of a chain of physiological processes. These contractions provide the required force to expel the fetus from the uterus. The inclusion of these physiological processes is, therefore, imperative when studying uterine contractions. In this study, an electro-chemo-mechanical model to replicate the excitation, activation, and contraction of uterine smooth muscle cells is developed. The presented modeling strategy enables efficient integration of knowledge about physiological processes at the cellular level to the organ level. The model is implemented in a three-dimensional finite element setting to simulate uterus contraction during labor in response to electrical discharges generated by pacemaker cells and propagated within the myometrium via gap junctions. Important clinical factors, such as uterine electrical activity and intrauterine pressure, are predicted using this simulation. The predictions are in agreement with clinically measured data reported in the literature. A parameter study is also carried out to investigate the impact of physiologically related parameters on the uterine contractility.     

Studies on Galalpha3-binding proteins: comparison of the glycosphingolipid binding specificities of Marasmius oreades lectin and Euonymus europaeus lectin

The carbohydrate binding preferences of the Galalpha3Galbeta4 GlcNAc-binding lectins from Marasmius oreades and Euonymus europaeus were examined by binding to glycosphingolipids on thin-layer chromatograms and in microtiter wells. The M. oreades lectin bound to Galalpha3-terminated glycosphingolipids with a preference for type 2 chains. The B6 type 2 glycosphingolipid (Galalpha3[Fucalpha2]Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer) was preferred over the B5 glycosphingolipid (Galalpha3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer), suggesting that the alpha2-linked Fuc is accommodated in the carbohydrate binding site, providing additional interactions. The lectin from E. europaeus had broader binding specificity. The B6 type 2 glycosphingolipid was the best ligand also for this lectin, but binding to the B6 type 1 glycosphingolipid (Galalpha3[Fucalpha2]Galbeta3GlcNAcbeta3Galbeta4Glcbeta1Cer) was also obtained. Furthermore, the H5 type 2 glycosphingolipid (Fucalpha2Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer), devoid of a terminal alpha3-linked Gal, was preferred over the the B5 glycosphingolipid, demonstrating a significant contribution to the binding affinity by the alpha2-linked Fuc. The more tolerant nature of the lectin from E. europaeus was also demonstrated by the binding of this lectin, but not the M. oreades lectin, to the x2 glycosphingolipid (GalNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer) and GlcNAcbeta3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer. The A6 type 2 glycosphingolipid (GalNAcalpha3[Fucalpha2]Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer) and GalNAcalpha3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1-Cer were not recognized by the lectins despite the interaction with B6 type 2 glycosphingolipid and the B5 glycosphingolipid. These observations are explained by the absolute requirement of a free hydroxyl in the 2-position of Galalpha3 and that the E. europaea lectin can accommodate a GlcNAc acetamido moiety close to this position by reorienting the terminal sugar, whereas the M. oreades lectin cannot.     

Alpha-lactalbumin unfolding is not sufficient to cause apoptosis, but is required for the conversion to HAMLET (human alpha-lactalbumin made lethal to tumor cells)

HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a complex of human alpha-lactalbumin and oleic acid (C18:1:9 cis) that kills tumor cells by an apoptosis-like mechanism. Previous studies have shown that a conformational change is required to form HAMLET from alpha-lactalbumin, and that a partially unfolded conformation is maintained in the HAMLET complex. This study examined if unfolding of alpha-lactalbumin is sufficient to induce cell death. We used the bovine alpha-lactalbumin Ca(2+) site mutant D87A, which is unable to bind Ca(2+), and thus remains partially unfolded regardless of solvent conditions. The D87A mutant protein was found to be inactive in the apoptosis assay, but could readily be converted to a HAMLET-like complex in the presence of oleic acid. BAMLET (bovine alpha-lactalbumin made lethal to tumor cells) and D87A-BAMLET complexes were both able to kill tumor cells. This activity was independent of the Ca(2+)site, as HAMLET maintained a high affinity for Ca(2+) but D87A-BAMLET was active with no Ca(2+) bound. We conclude that partial unfolding of alpha-lactalbumin is necessary but not sufficient to trigger cell death, and that the activity of HAMLET is defined both by the protein and the lipid cofactor. Furthermore, a functional Ca(2+)-binding site is not required for conversion of alpha-lactalbumin to the active complex or to cause cell death. This suggests that the lipid cofactor stabilizes the altered fold without interfering with the Ca(2+)site.     

Clinical relevance of serum angiogenic activity in patients with transitional cell carcinoma of the bladder

Angiogenesis is essential for tumor growth and progression and is mediated by positive and negative regulators of vessel growth. Since angiogenic mediators found in patient serum have been postulated to reflect the angiogenic potential of a malignant tumor, we investigated the angiogenic activity in the serum of patients with transitional cell carcinoma (TCC). The data were correlated to tumor characteristics and the clinical course of the patients. Eighty-one patients with transitional cell carcinoma and 53 control persons were included in the study. Preoperative serum samples were collected and both vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were quantified by ELISA. Additionally, the serum evoked proliferative activity on human umbilical vein endothelial cells (HUVEC) was evaluated. Data were compared to the clinical course of the patients. Serum of tumor patients significantly enhanced the proliferative capacity of HUVEC, compared to cells grown in standard culture medium (p = 0.0032), but not when compared to serum from control persons. Serum from patients with superficial TCC and well differentiated tumors induced a significantly higher angiogenic response (ANG(hi)) than serum from patients with poorly differentiated and invasive carcinomas (ANG(lo); p = 0.037). VEGF level of ANG(hi) serum was 384.22 +/- 247.76 pg/ml (n = 37) which significantly differed from mean VEGF level detected in ANG(lo) serum (247.72 +/- 211.93 pg/ml, n = 42; p = 0.019). Similarly, mean bFGF levels were 9.58 +/- 5.91 pg/ml in ANG(hi) serum versus 5.74 +/- 3.52 pg/ml) in ANG(lo) serum (p = 0.0043). A negative correlation was established between VEGF/bFGF serum concentration and patient prognosis. The experiments demonstrate a positive correlation between VEGF and bFGF serum level and endothelial proliferation in vitro. The inverse relationship between angiogenic activity and tumor stage might disclose information about angiogenesis and tumor progression in TCC.     

Modulation of physiological performance by temperature and salinity in the sugar kelp Saccharina latissima

The sugar kelp Saccharina latissima experiences a wide range of environmental conditions along its geographical and vertical distribution range. Temperature and salinity are two critical drivers influencing growth, photosynthesis and biochemical composition. Moreover, interactive effects might modify the results described for single effects. In shallow water coastal systems, exposure to rising temperatures and low salinity are expected as consequence of global warming, increased precipitation and coastal run‐off. To understand the acclimation mechanisms of S. latissima to changes in temperature and salinity and their interactions, we performed a mechanistic laboratory experiment in which juvenile sporophytes from Brittany, France were exposed to a combination of three temperatures (0, 8 and 15°C) and two salinity levels (20 and 30 psu (practical salinity units)). After a temperature acclimation of 7 days, sporophytes were exposed to low salinity (20 psu) for a period of 11 days. Growth, and maximal quantum yield of photosystem II (Fv/Fm), pigments, mannitol content and C:N ratio were measured over time. We report for the first time in S. latissima a fivefold increase in the osmolyte mannitol in response to low temperature (0°C) compared to 8 and 15°C that may have ecological and economic implications. Low temperatures significantly affected all parameters, mostly in a negative way. Chlorophyll a, the accessory pigment pool, growth and Fv/Fm were significantly lower at 0°C, while the de‐epoxidation state of the xanthophyll cycle was increased at both 0 and 8°C compared to 15°C. Mannitol content and growth decreased with decreased salinity; in contrast, pigment content and Fv/Fm were to a large extent irresponsive to salinity. In comparison to S. latissima originating from an Arctic population, despite some reported differences, this study reveals a remarkably similar impact of temperature and salinity variation, reflecting the large degree of adaptability in this species.