"海洋2号"的幕后

庞大的维生系统，为海洋馆人工模拟的海洋生态提供了保障。     

The prokaryote-eukaryote dichotomy: meanings and mythology.

Drawing on documents both published and archival, this paper explains how the prokaryote-eukaryote dichotomy of the 1960s was constructed, the purposes it served, and what it implied in terms of classification and phylogeny. In doing so, I first show how the concept was attributed to Edouard Chatton and the context in which he introduced the terms. Following, I examine the context in which the terms were reintroduced into biology in 1962 by Roger Stanier and C. B. van Niel. I study the discourse over the subsequent decade to understand how the organizational dichotomy took on the form of a natural classification as the kingdom Monera or superkingdom Procaryotae. Stanier and van Niel admitted that, in regard to constructing a natural classification of bacteria, structural characteristics were no more useful than physiological properties. They repeatedly denied that bacterial phylogenetics was possible. I thus examine the great historical irony that the "prokaryote," in both its organizational and phylogenetic senses, was defined (negatively) on the basis of structure. Finally, we see how phylogenetic research based on 16S rRNA led by Carl Woese and his collaborators confronted the prokaryote concept while moving microbiology to the center of evolutionary biology.     

The Language You Cry In: The Story of a Mende Song

The Language You Cry In: The Story of. Mende Song. 1998. 52 minutes, color. video by Alvaro Toepke and Angel Serrano. In English and Mende with English subtitles. For more information contact California Newsreel, 149 Ninth Street/420, San Francisco, CA 94103.     

Pineal antigonadotrophic substances: polypeptides and indoles.

Two categories of compounds, polypeptides and indoles, are discussed in terms of their potential importance as pineal antigonadotrophic substances. One of the polypeptides has been structurally identified as arginine vasotocin. Arginine vasotocin and other peptides of unknown structural identity have been found to be strongly antigonadotrophic in experimental animals. Besides melatonin, the gonad-inhibiting ability of several other pineal indoles including serotonin, 5-hydroxytryptophol, 5-methoxytryptophol and N-acetylserotonin was considered. In addition to its gonad suppressing ability, in three species of rodents melatonin has been shown to negate the antigonadotrophic effects of the pineal gland, i.e., it acts as a counter antigonadotrophic factor. A theory is presented in which the indoles may interact with the polypeptides in the control and/or the synthesis of the latter compounds. A mechanism for the secretion of pineal polypeptides is also considered. It is concluded that it is premature to classify any pineal constituent, be it a polypeptide or an indole, as $\text{the}$ antigonadotrophic factor of the mammalian pineal gland.     

The history and mythology of Endymion nonscriptus

Background: Biological invasions are one of the major causes of biodiversity loss, yet remain rather understudied in tropical environments. The Australian palm tree Archontophoenix cunninghamiana was introduced into Brazil for ornamental purposes, but has become an invasive species in urban and suburban forest patches. The substitution of A. cunninghamiana by the native palm Euterpe edulis has been proposed as a management action.

Aims: We aimed to evaluate the regeneration potential of these two palm species in an Atlantic forest remnant in south-eastern Brazil where both species occur.

Methods: We compared seedling establishment and seed longevity of both species through seed sowing, and also measured the contribution of A. cunninghamiana to the local seed rain and seed bank.

Results: Nearly half of the non-anemochoric diaspores collected from the seed rain belonged to A. cunninghamiana, which represented a high propagule pressure in the community. The distribution of the alien palm seeds in the seed rain correlated with the distribution of nearby young and adult individuals inside the forest. Neither A. cunninghamiana nor E. edulis appeared to have a persistent seed bank in a burial experiment; seedling survival experiments suggested a much better performance for A. cunninghamiana, which had a survival rate of ca. 30% compared with a rate of only 3.5% for E. edulis.

Conclusions: The results suggest a higher regeneration capacity for the alien palm over the native species when co-occurring in a forest fragment. Management actions are thus proposed to reduce a potential biological invasion process.     

Siberian Survival: The Nenets and Their Story.

Siberian Survival: The Nenets and Their Story. Andrei V. Golovnev and Gail Osherenko. Ithaca: Cornell University Press, 1999. 176 pp.     

Jaws: The Inside Story. The Metabolism of Elasmobranch Fishes

Elasmobranchs are of metabolic interest for several reasons, including their primitive evolutionary position, their osmotic strategy and their low incidence of neoplasia. Some aspects of the metabolism of elasmobranch fishes are unique when compared with those of the other vertebrates. Although many features of their metabolism can be attributed to their primitive evolutionary position (e.g., fewer isoforms of enzymes and other proteins), some unique features appear to be related to the unusual solute system (urea and methylamines) used by elasmobranchs. The solute system exerts widespread effects, which has an impact on the metabolism of lipids, ketone bodies and amino acids and the structure of proteins and membranes. Effects of urea on the transport of lipid may influence aspects of lipid metabolism, reducing extrahepatic lipid catabolism via effects on nonesterified fatty acid transport and enhancing a need for reliance on ketone bodies. Amino acid metabolism of elasmobranchs is also heavily influenced by the need for continuous synthesis of urea with glutamine as the nitrogen donor. These effects, in turn, may play a role in their low incidence of cancer. Specifically, the reduced availability of glutamine (an important nutrient for rapidly growing cells) coupled with the low levels of nonesterified fatty acids in the blood reduces the availability of molecules essential for tumor growth. This metabolic design may thus provide marine elasmobranchs with a “systemic” resistance to cancer.     

Evolution of The Vertebrate Pineal Gland: The Aanat Hypothesis

The defining feature of the pineal gland is the capacity to function as a melatonin factory that operates on a ∼24 h schedule, reflecting the unique synthetic capacities of the pinealocyte. Melatonin synthesis is typically elevated at night and serves to provide the organism with a signal of nighttime. Melatonin levels can be viewed as hands of the clock. Issues relating to the evolutionary events leading up to the immergence of this system have not received significant attention. When did melatonin synthesis appear in the evolutionary line leading to vertebrates? When did a distinct pineal gland first appear? What were the forces driving this evolutionary trend? As more knowledge has grown about the pinealocyte and the relationship it has to retinal photoreceptors, it has become possible to generate a plausible hypothesis to explain how the pineal gland and the melatonin rhythm evolved. At the heart of the hypothesis is the melatonin rhythm enzyme arylalkylamine N-acetyltransferase (AANAT). The advances supporting the hypothesis will be reviewed here and expanded beyond the original foundation; the hypothesis and its implications will be addressed.     

Evolution of The Vertebrate Pineal Gland: The Aanat Hypothesis

The defining feature of the pineal gland is the capacity to function as a melatonin factory that operates on a ～24 h schedule, reflecting the unique synthetic capacities of the pinealocyte. Melatonin synthesis is typically elevated at night and serves to provide the organism with a signal of nighttime. Melatonin levels can be viewed as hands of the clock. Issues relating to the evolutionary events leading up to the immergence of this system have not received significant attention. When did melatonin synthesis appear in the evolutionary line leading to vertebrates? When did a distinct pineal gland first appear? What were the forces driving this evolutionary trend? As more knowledge has grown about the pinealocyte and the relationship it has to retinal photoreceptors, it has become possible to generate a plausible hypothesis to explain how the pineal gland and the melatonin rhythm evolved. At the heart of the hypothesis is the melatonin rhythm enzyme arylalkylamine N‐acetyltransferase (AANAT). The advances supporting the hypothesis will be reviewed here and expanded beyond the original foundation; the hypothesis and its implications will be addressed.     

The mitochondrial genome of Cygnus columbianus, the Whistling Swan.

The nucleotide sequence of the mitochondrial genome of the Whistling Swan, Cygnus columbianus, is reported. Many of the features common to avian mitochondrial genomes are present in C. columbianus and are described here. The gene order is the same as in Gallus gallus. The sequence of this mitochondrial genome allows relationships within the family Anatidae (swans, geese and ducks) to be reconsidered in the light of a large suite of mitochondrial characters. Protein-coding gene sequences of C. columbianus were concatenated to form a supergene, which was analyzed phylogenetically with similar constructs from previously published avian genomes. Relationships within Anatidae and between the Anatidae and the galliform birds were addressed. Three independent phylogenetic methods confirmed traditional classifications and the existence of the Galloanseres clade.