The viking biological investigations: Review and status

The three experimental approaches incorporated into the Viking biology instrument have yielded results that are most readily explained as nonbiological phenomena. The predominant view among investigators trying to simulate the Mars results is that the surface material of Mars contains strongly oxidizing compounds which would account for many of the more intense reactions seen on Mars. Other mechanisms are also currently being proposed and studied.     

Pollution effects in Visakhapatnam harbour,India: An overview of 23 years of investigations and monitoring

Visakhapatnam Harbour, a semi-enclosed water body on the east coast of India, is subject to a high degree of pollution caused by industrial and urban wastes. Studies carried out during the last twenty years or so at 6 selected stations in the harbour revealed appreciable hydrographic and biotic changes. Over the years, the concentration of nitrites (max. 5 mg/l) and phosphates (9.6 mg/l) has increased. Dissolved oxygen registered all-time-high values (max. 21.6 mg/l) caused by periodic outbursts of phytoplankton, notably,Skeletonema costatum and other species. Benthic conditions have also changed and only certain pollution-tolerant species (e.g.Capitella capitata) inhabited the bottom sediments that contained a heavy load (2.5%) of organic matter. In the harbour, increased pollution led to the disappearence of stenoecious species and their replacement with other forms known for their tolerance to pollution. The paper describes the major changes which have occurred in water quality and organisms in the harbour as a result of pollution increase during the last two decades.     

On the morphology of the fossil hominids of Laguna Beach and Los Angeles

Los Angeles Man and Laguna Woman are two of the oldest, absolutely dated fossil hominids in America. With their 23,600 years B.P. and 17,150 ± 1470 years B.P., respectively, these two individuals are more than 10,000 years older than most of the absolute dated human remains discovered on this continent. They are described here in detail and compared with early representatives of our species from North America and Asia. Moreover, an attempt will be made to classify them typologically.     

Chemical and biological investigations of beta-oligoarginines

In view of the important role arginine plays in living organisms as the free amino acid and, especially, as a residue in peptides and proteins, the homologous beta-homoarginines are central in our investigations of beta-peptides (Fig. 1). The preparation of beta2-homoarginine derivatives suitably protected for solution- or solid-phase peptide syntheses is described with full experimental detail (9 and 12 in Scheme 1). The readily available Fmoc-beta3 hArg(Boc)2-OH is used for manual solid-phase synthesis of beta3-oligoarginines (on Rink amide or Rink amide AM resin) either by single amino acid coupling (Scheme 3) or, much better, by dimer-fragment coupling (Scheme 4). In this way, beta3-oligoarginine amides composed of 4, 6, 7, 8, and 10 residues, both with and without fluorescein labelling, were synthesized (Schemes 2-4), purified by preparative HPLC and identified by high-resolution mass spectrometry. The free amino acids (R)- and (S)-H-beta2 hArg-OH and (S)-H-beta3 hArg-OH were tested for their ability to function as substrates for NO synthase (iNOS); the beta3-oligoarginine amides (5, 6, and 7 residues) were tested for antibacterial (against six pathogens) and hemolytic (against rat and human erythrocytes) activities. All test results were negative: none of the free beta-homoarginines induced NO formation (Fig. 3), and there was no lysis of erythrocytes (concentrations up to 100 microM; Table 1), and no significant antibiotic activity (MIC > or = 64 microg/ml; Table 2). Cell-penetration studies with the fluorescence-labelled, peptidase-resistant beta3-oligoarginine amides were carried out with HeLa cells and human foreskin keratinocytes (HFKs). The results obtained with fluorescence microscopy are: i) the longer-chain beta-oligoarginine amides (8 and 10 residues; Figs. 4-6) enter the cells and end up in the nuclei, especially in the nucleoli, irrespective of temperature (37 degrees and 4 degrees with HFKs) or pretreatment with NaN3 (with HFKs), indicating a non-endocytotic and non-energy-dependent uptake mechanism; ii) the beta-tetraarginine derivative occupies the cell surface but does not enter the cells (with HeLa); iii) the cell-growth rate of the HFKs is not affected by a 1-microM concentration of the fluorescence-labelled beta-octaarginine amide (Fig. 7), i.e., there is no antiproliferative effect. In vivo experiments with mouse skin and the beta-octaarginine derivative show migration of the beta-peptide throughout the epidermis (Fig. 8). As a contribution to understanding the mechanism, we have also studied the behavior of fluorescence-labelled beta-octa- and beta-decaarginine amides (TFA salts) towards giant unilamellar vesicles (GUVs) built of neutral (POPC) or anionic (POPC/POPG mixtures) phospholipids: the beta-oligoarginine amides bind tightly to the surface of anionic GUVs but do not penetrate the lipid bilayer (Fig. 9) as they do with living cells. In contrast, a beta-heptapeptide FL-22, which had been used as a negative control sample for the cell-penetration experiments, entered the GUVs of negative surface charge. Thus, the mechanisms of cell and GUV-model penetration appear to be different. Finally, the possible applications and implications of the 'protein transduction' by beta-oligoarginines are discussed.     

Phototrophic marine benthic microbiomes: the ecophysiology of these biological entities

Phototrophic biofilms are multispecies, self-sustaining and largely closed microbial ecosystems. They form macroscopic structures such as microbial mats and stromatolites. These sunlight-driven consortia consist of a number of functional groups of microorganisms that recycle the elements internally. Particularly, the sulfur cycle is discussed in more detail as this is fundamental to marine benthic microbial communities and because recently exciting new insights have been obtained. The cycling of elements demands a tight tuning of the various metabolic processes and require cooperation between the different groups of microorganisms. This is likely achieved through cell-to-cell communication and a biological clock. Biofilms may be considered as a macroscopic biological entity with its own physiology. We review the various components of some marine phototrophic biofilms and discuss their roles in the system. The importance of extracellular polymeric substances (EPS) as the matrix for biofilm metabolism and as substrate for biofilm microorganisms is discussed. We particularly assess the importance of extracellular DNA, horizontal gene transfer and viruses for the generation of genetic diversity and innovation, and for rendering resilience to external forcing to these biological entities.     

原生动物在生物监测中的作用与应用

原生动物是水生态系统的重要组成部分,并在其中发挥着重要的生态作用。在水环境质量变化评价与发展趋势预测中,原生动物可作为指示生物来衡量水体的受污染程度。探讨了原生动物在水体监测中的作用及实际应用情况,展望了原生动物在生物监测中的应用前景。     

Na+,K+-ATPase: 40 years of investigations

Nobel Prize of 1997 in chemistry was awarded to three scientists fruitfully working in bioenergetics. J. Walker and P. Boyer were awarded the Prize for studies of structure and mechanism of functioning of the H+-transporting (mitochondrial) adenosine triphosphatase. The decision of the Nobel Committee was not unexpected, since these works were very impressive. Special attention was drawn to the fact that the investigations of Walker, the recognized specialist in protein structure, made possible the experimental confirmation of regularities in the mitochondrial ATPase functioning discovered by P. Boyer. The third member of this triumph of bioenergetics is Jens-Christian Skou who described the Na+,K+-activated ATPase in 1957 and then characterized the enzyme properties in detail. Forty years of his scientific biography were devoted to this enzyme. Along with accumulation of scientific knowledge, that constituted the fundamental contribution to bioenergetics (J.Skou is rightfully considered as one of founders of this branch in the present-day biology), the world-wide known school of scientists was established, and starting from 1974, members of this school organize regular conferences on this enzyme.     

Silibinin phosphodiester glyco-conjugates: Synthesis,redox behaviour and biological investigations

New silibinin phosphodiester glyco-conjugates were synthesized by efficient phosphoramidite chemistry and were fully characterized by 2D-NMR. A wide-ranging study focused on the determination of their pKa and E° values as well as on their radical scavenging activities by different assays (DPPH, ABTS⁺ and HRSA) was conducted. The new glyco-conjugates are more water-soluble than silibinin, and their radical scavenging activities are higher than those of silibinin. The conjugation therefore improves both the water solubilities and antioxidant activities of the flavonolignan moieties. The serum stability was evaluated under physiological conditions, and the glyco-conjugates degraded with half-lives of 40–70 h, making them useful in pro-drug approaches. We started by treating androgen-dependent prostate cancer (PCa) LNCaP cells and then expanded our studies to androgen-independent PCa PC3 and DU145 cells. In most cases, the new derivatives significantly reduced both total and live cell numbers, albeit at different levels. Anti-HIV activities were evaluated and the glucosamine-phosphate silibinin derivative showed higher activity (IC₅₀ = 73 μM) than silibinin.     

The effects of habitat complexity and hydraulic conditions on the establishment of benthic stream macroalgae

相似文献   

The valve movement response of mussels: a tool in biological monitoring

Biological sensors are becoming more important to monitor the quality of the aquatic environment. In this paper the valve movement response of freshwater (Dreissena polymorpha) and marine (Mytilus edulis) mussels is presented as a tool in monitoring studies. Examples of various methods for data storage and data treatment are presented, elucidating easier operation and lower detection limits. Several applications are mentioned, including an early warning system based on this valve movement response of mussels.     

Physicochemical conditions and benthic macroinvertebrates of a tertiary sewage treatment system

Hydrobiologia - Physicochemical conditions and benthic macroinvertebrates were studied in the Beaumont, Texas sewage treatment plant from August, 1973 to June, 1974. Physicochemical conditions...     

Twenty years of research into medicinal plants: Results and perspectives

Over the years 1981 to 2001 there has been a rapid evolution of research into medicinal plants. The major improvement has been the introduction of simple and predictive bioassays for bioactivity-guided isolation. Radical developments in separation methods have also taken place. Another important addition has been the development of hyphenated techniques involving HPLC: LC/UV, LC/MS, LC/MSⁿ and LC/NMR. These are indispensable nowadays for the early detection and identification of new compounds in crude plant extracts. Hyphenated techniques allow an efficient targeted isolation approach for the discovery of new lead compounds. Other areas of increasing importance include the investigation of toxic constituents of plants and phytomedicines, and the effects of genetic modifications on plant secondary metabolites. This revised version was published online in June 2006 with corrections to the Cover Date.     

The implications of the precautionary principle for biological monitoring

Marine biological monitoring programmes frequently attempt to determine “safe” levels of contamination, based on assumptions about the assimilative capacity of the environment. This paper argues that such assumptions lack scientific rigour, and do not form the basis upon which a precautionary policy can be built. It notes the problems associated with assessing toxicological effects, but centres its attention on the crucial (yet far less discussed) weaknesses in theoretical ecology that make it extremely unlikely that biological monitoring can determine safe levels of contamination that leave ecosystems unaffected. It is argued that many marine biologists, if pressed, would concede these shortcomings but believe that, in the face of the technical difficulties and high costs of pollution prevention, we have no choice but to use such methods. This paper argues, with examples, that pollution prevention, often with considerable economic savings, is becoming a reality for even the most problematic substances. The difficulty is that the development of “clean production” methods lie outside the sphere of interest of those carrying out monitoring, so that measures that attempt to determine safe levels of contamination continue to be advocated. This gulf needs to be bridged so that the continuation of monitoring programmes that are part of dilute and disperse policies become regarded as inappropriate, indeed unethical. The paper concludes that this does not mean the end of marine monitoring. Instead, reliable methods for assessing physical levels of contamination will be required to determine whether the reduction targets set—as part of the introduction of clean production—are being met. Formidable difficulties will remain, requiring a precautious approach. Nevertheless, monitoring will no longer carry the burden of attempting to demonstrate that a particular level of environmental contamination is safe, which is currently destroying its scientific credibility.     

Sluggish methane discharge and biological traits of benthic invertebrates in Lake Baikal

Hydrobiologia - The biological traits of invertebrates inhabiting freshwater methane seeps are poorly understood. We analysed the relationship between invertebrate abundance and environmental...     

The standardization of experimental investigations of biological effects of low frequency electric and magnetic fields

Many investigations show that electric and magnetic fields of low frequency may cause biological effects. However, the results of experiments differ considerably. In this paper, possible reasons for the limited reproducibility are pointed out, i.e., problems of generation, detection and definition of artificial fields. In particular, it is shown mathematically that the usual statements of electric field intensity are strongly misleading. The actual intensity is proportional to the ratio of the object height and the electrode distance as well as to the thinness of the object. Recommendations for the standardization of future investigations are given.