Temporal variation of lysosomal capacities in relation to susceptibility of mussels, Mytilus edulis, to summer mortality

We examined the temporal variation of lysosomal enzyme activities and lysosomal membrane stability in two stocks of blue mussels (Mytilus edulis L., 1758) from the Magdalen Islands which differ in their susceptibility to summer mass-mortality. The activity of lysosomal enzymes reflects the autolytic capacity which could be used during the transfer of reserves between storage and reproductive tissues or for mobilisation of reserves for energy requirements. The peak of lysosomal enzyme activities in mantle tissue in June 1992 probably was related with autolysis of storage cells to support maturation of the developing gametes. A second peak of lysosomal enzyme activity which occurred in mid- August of 1992 and 1993 may help to cover energetic requirements of maintenance metabolism during this period of high temperatures and reduced food quality. Measures of the destabilization of lysosomal membranes in the digestive gland confirmed that mussels showed a significant stress response in mid-August. Mussels from the stock with a higher susceptibility to summer mortality underwent a longer period of stress and accumulated less glycogen between spawning and the stressful period in mid-August than mussels from the more resistant stock. In conclusion, our field observations demonstrate high activities of lysosomes not only in spawning periods but also during stressful periods of high temperatures and reduced food quality. Received: 23 September 1997 / Accepted: 11 June 1998     

Use of beetroot fibers to clean water contaminated with heavy metals,to soften hard water,and to desalinate seawater

In this article we describe the use of beetroot fibers in treating water contaminated with heavy metals, in softening hard water, and in desalinating seawater. The study was carried out with either beetroot fibers or powdered fibers using a laboratory column with a fixed bed. The effectiveness of the method and the effect of the pH on it were monitored by atomic absorption spectrometry, infrared spectroscopy, conductivity measurements, and a volumetric method. The optimum pH range for all the treatment was found to be between 6.0 and 6.6. The heavy metals included in this study were lead, copper, nickel, and zinc. The amount of heavy metals retained by the fibers or the powder was significant in each case. The retention capacity was the strongest for lead and the weakest for nickel. In the case of hard water and seawater studies, our experiments revealed a dramatic decrease in total dissolved solids (TDS), indicating the potential of the method as an aid or an alternative to conventional methods.     

Factors Associated with Alien Plants Transitioning from Casual, to Naturalized, to Invasive

Abstract:  To explain current plant invasions, or predict future ones, more knowledge on which factors increase the probability of alien species becoming naturalized and subsequently invasive is needed. We created a database of the alien plants in seminatural habitats in Ireland that included data on taxonomy, invasive status, invasion history, distribution, and biological and ecological plant characteristics. We used information from this database to determine the importance of these factors in increasing the ability of species to become naturalized and invasive. More specifically, we used two multiple logistic regressions to identify factors that distinguish naturalized from casual alien plant species and invasive from noninvasive, naturalized alien species. Clonal growth, moisture-indicator value, nitrogen-indicator value, native range, and date of first record affected (in order of decreasing importance) the probability of naturalization. Factors that distinguished invasive from noninvasive species were ornamental introduction, hermaphrodite flowers, pollination mode, being invasive elsewhere, onset of flowering season, moisture-indicator value, native range, and date of first record. Incorporation of phylogenetic information had little influence on the results, suggesting that the capacity of alien species to naturalize and become invasive evolved largely independently in several phylogenetic lineages. Whereas some of the variables were important for both transitions, others were only important for naturalization or for invasion. This emphasizes the importance of studying different stages of the invasion process when looking for mechanisms of becoming a successful invasive plant, instead of simply comparing invasive with noninvasive alien species. Our results also suggest that a combination of species traits and other variables is likely to produce the most accurate prediction of invasions.     

Acute exposure to naphthalene reduces oxyregulating capacity of the brown shrimp, Penaeus aztecus, subjected to progressive hypoxia

The brown shrimp, Penaeus aztecus, in the northern Gulf of Mexico is faced with dual stresses of environmental hypoxia, which occurs as a result of oxygen depletion from microbial decomposition of organic materials from algal blooms, and pollution from polycyclic aromatic hydrocarbons (PAHs) from petroleum and gas production on the continental shelf of the northern Gulf of Mexico. This study investigated the effect of naphthalene, a PAH, on oxyregulating capacity of P. aztecus, when shrimps were subjected to progressive hypoxia. It was found that P. aztecus is an oxyregulator with a critical oxygen concentration of 2.53 mg/l at 19–21°C, below which the animal becomes an oxyconformer. Acute exposure to naphthalene at 2.0 mg/l significantly reduced the oxyregulating capacity by 112%. This is the first report on the alteration of an aquatic animal’s oxyregulating capacity by a PAH. Possible mechanism for the impaired oxyregulation in the presence of naphthalene was discussed.     

Cyclodextrins,from molecules to applications

Cyclodextrins are among the most remarkable macrocyclic molecules with significant theoretical and practical impacts in chemistry and biology. Cyclodextrins belong to the family of cage molecules due to their structure, which is composed of a hydrophobic cavity that can encapsulate other molecules. Indeed, the most characteristic feature of these compounds is their ability to form inclusion complexes with various molecules through host–guest interactions. This is at the origin of many applications. It is well known and widely reported in the literature that cyclodextrins and their derivatives have a wide variety of practical applications including pharmacy, medicine, foods, cosmetics, toiletries, catalysis, chromatography, biotechnology, nanotechnology, and textile industry. Cyclodextrins are also the object of numerous fundamental studies. In this review, we chose to highlight selected works on cyclodextrins published over the last 5 years by different research groups. The main objective is to summarize some of the recent developments related to the applications of cyclodextrins.     

Contributions of paraecologists and parataxonomists to research,conservation, and social development

Citizen science has been gaining momentum in the United States and Europe, where citizens are literate and often interested in science. However, in developing countries, which have a dire need for environmental data, such programs are slow to emerge, despite the large and untapped human resources in close proximity to areas of high biodiversity and poorly known floras and faunas. Thus, we propose that the parataxonomist and paraecologist approach, which originates from citizen‐based science, is well suited to rural areas in developing countries. Being a paraecologist or a parataxonomist is a vocation and entails full‐time employment underpinned by extensive training, whereas citizen science involves the temporary engagement of volunteers. Both approaches have their merits depending on the context and objectives of the research. We examined 4 ongoing paraecologist or parataxonomist programs in Costa Rica, India, Papua New Guinea, and southern Africa and compared their origins, long‐term objectives, implementation strategies, activities, key challenges, achievements, and implications for resident communities. The programs supported ongoing research on biodiversity assessment, monitoring, and management, and participants engaged in non‐academic capacity development in these fields. The programs in Southern Africa related to specific projects, whereas the programs in Costa Rica, India, and Papua New Guinea were designed for the long term, provided sufficient funding was available. The main focus of the paraecologists’ and parataxonomists’ activities ranged from collection and processing of specimens (Costa Rica and Papua New Guinea) or of socioeconomic and natural science data (India and Southern Africa) to communication between scientists and residents (India and Southern Africa). As members of both the local land user and research communities, paraecologists and parataxonomists can greatly improve the flow of biodiversity information to all users, from local stakeholders to international academia.     

Electrocardiogram of a marine fish,Pagrus major,exposed to red tide plankton,Chattonella marina

Examinations of the electrocardiogram of Pagrus major exposed to Chattonella marina, a planktonic organism causing red tide, were made to determine the physiological effects on fish. The heart rate decreased as a result of the extention in the interval between T and P waves. The decrease in heart rate with the extended intervals between T and P waves was also recognized in the condition of decreased dissolved oxygen. Also, the decrease in heart rate of the fish exposed to the red tide occurred while the fish was struggling. This reduction seems to be caused by the strong tension of the vagal nerve. Upon exposure to C. marina at high cell concentration, the heart beat at a very low frequency after 30 min. The very low heart rate is expected to limit seriously the oxygen uptake by the gill, because the cardiac output is probably very low in this situation.     

Pigeon homing in relation to geomagnetic,gravitational, topographical,and meteorological conditions

Summary Experienced homing pigeons were released at sites unfamiliar to them and with magnetic and gravity anomalies as well as in areas with rather normal fields throughout the FRG (41 releases when sunny, 14 when overcast; Figs. 1–3). The second-order release data were subjected to both univariate and multivariate statistical analysis (stepwise regression, factor analysis). The magnetic field strength and its gradients within the 1-km circle around the release site were determined from aeromagnetic maps of the anomalies of magnetic total intensity. Analogous variables were derived from gravity anomaly maps. It was tested whether the pigeons fly along that gradient to minimize the difference between the magnetic or gravity field at the release site and the loft at maximum rate. Further independent variables described magnetic K index, day-to-day variations of the magnetic components, topography, meteorological conditions, the number of the releases the pigeons had done, and the distance.Over magnetic anomalies widely varying in strength (departing – 250 nT to 300 nT from normal 600 m above ground), extent, and distance from loft, the pigeons vanished with less deviation from the homeward direction and faster than they did in areas with less irregular fields under sunny conditions; this is in contrast to other studies on magnetic anomalies, except one. At sites of gravity anomalies (15–49 mgal), the pigeons were significantly less homeward oriented and homed slower than at less anomalous sites (–9 to 14 mgal).Variables related to gravity were best predictors in 8 and and second predictors in 3 out of 15 regression analyses of the navigational parameters for the releases under sun. Six times the (absolute) amount of the gravity difference between the release site and the loft was selected first (Figs. 7B, C, 8B, C). The results suggest gravity to be involved in navigation as the pigeons' distance measure. Homeward directedness declined with increasing amount of the gravity gradient in the first 12 releases under sunny skies as well as when overcast (Fig. 8A). A preferred compass direction towards north-northeast was determined, being closest to the grand mean vector of the ascending gravity gradient (Fig. 6). The analyses failed to show directional preferences as assumed by the hypotheses tested. Temperature and degree of cloud cover provided some information for predicting mean vector lengths and mean vanishing times, respectively. The surface wind component in the homeward direction was correlated with median homing performances.     

Integrating Paleobiology,Archeology, and History to Inform Biological Conservation

The search for novel approaches to establishing ecological baselines (reference conditions) is constrained by the fact that most ecological studies span the past few decades, at most, and investigate ecosystems that have been substantially altered by human activities for decades, centuries, or more. Paleobiology, archeology, and history provide historical ecological context for biological conservation, remediation, and restoration. We argue that linking historical ecology explicitly with conservation can help unify related disciplines of conservation paleobiology, conservation archeobiology, and environmental history. Differences in the spatial and temporal resolution and extent (scale) of prehistoric, historic, and modern ecological data remain obstacles to integrating historical ecology and conservation biology, but the prolonged temporal extents of historical ecological data can help establish more complete baselines for restoration, document a historical range of ecological variability, and assist in determining desired future conditions. We used the eastern oyster (Crassostrea virginica) fishery of the Chesapeake Bay (U.S.A.) to demonstrate the utility of historical ecological data for elucidating oyster conservation and the need for an approach to conservation that transcends disciplinary boundaries. Historical ecological studies from the Chesapeake have documented dramatic declines (as much as 99%) in oyster abundance since the early to mid‐1800s, changes in oyster size in response to different nutrient levels from the sixteenth to nineteenth centuries, and substantial reductions in oyster accretion rates (from 10 mm/year to effectively 0 mm/year) from the Late Holocene to modern times. Better integration of different historical ecological data sets and increased collaboration between paleobiologists, geologists, archeologists, environmental historians, and ecologists to create standardized research designs and methodologies will help unify prehistoric, historic, and modern time perspectives on biological conservation. Integración de Paleobiología, Arqueología e Historia para Informar a la Biología de la Conservación     

大熊猫迁居碧峰峡新生境的适应能力研究

2003年10月至2005年10月,对21只圈养于四川卧龙和3只圈养于蜂桶寨自然保护区的大熊猫迁居到雅安碧峰峡全新生境,并以散放养方式保护的大熊猫种群的适应能力进行了研究.环境年平均气温为13.9℃±7.5℃,夏季(6～8月)较炎热(22.3℃±3.8℃),冬季(12～2月)较寒冷(4.8℃±3.9℃);动物对竹子取食秋季最少(5.9kg±1.3kg),冬季最多(8.1kg±2.0kg),5月为次高峰期(8.0kg±1.5kg),喜食竹类为刺竹→苦竹→水竹;动物平均日活动时间6.5h,活动节律和时间与卧龙比较有极显著的改变(P<0.01,N=24);动物对环境、食物等的改变有较强的适应能力,约需3～6mo;但完全适应自然气候等因素的改变则需1a;疾病的发生频率依次为:消化道疾病、皮肤病、蛔虫感染、呼吸道疾病、脑血管疾病等;除气候湿热、土壤粘结、日照偏少、风雨雷电较多等自然因素外,动物在生理、行为、采食、排泄、抗病力及生长发育等各方面基本正常.图4表2参22