Carbon functionalities in amber

High-resolution nuclear magnetic resonance spectra of the carbon nuclei in powdered amber, obtained by using the techniques of magic angle spinning and cross polarization, provide detailed information about the types of carbon functionalities. The entire spectrum of Baltic amber (succinite) is identical for several samples. Baltic amber shows minor differences from Sicilian amber and drastic differences from Burmese, Romanian, and Bohemian ambers.     

An upper eocene frog from the dominican republic and its implication for Caribbean biogeography

A frog of the leptodactylid genus Eleutherodactylus is reported from Eocene amber found in the Dominican Republic. It is the first described amphibian fossil in amber, and the oldest complete lissamphibian fossil from Mesoamerica (Central America and Mexico). Dating of the amber matrix indicates that by the end of the Eocene a diverse fauna was present in the Antilles, much earlier than has generally been proposed. The presence of this and other amber fossils from this same age suggests that Tertiary patterns of landmass movements were significant in determining the present distribution of species.     

A diverse assemblage of Late Cretaceous dinosaur and bird feathers from Canadian amber

The fossil record of early feathers has relied on carbonized compressions that lack fine structural detail. Specimens in amber are preserved in greater detail, but they are rare. Late Cretaceous coal-rich strata from western Canada provide the richest and most diverse Mesozoic feather assemblage yet reported from amber. The fossils include primitive structures closely matching the protofeathers of nonavian dinosaurs, offering new insights into their structure and function. Additional derived morphologies confirm that plumage specialized for flight and underwater diving had evolved in Late Cretaceous birds. Because amber preserves feather structure and pigmentation in unmatched detail, these fossils provide novel insights regarding feather evolution.     

东南亚国家在农产品国际贸易中的黄箱政策——以越南,印尼,马来西亚,菲律宾为例

东南亚国家在经济发展状况,农产品贸易等方面具有很大的相似性.黄箱政策作为许多国家目前使用的国内支持政策,在国际贸易中扮演着十分重要的角色,因此,在世界各国要求削减黄箱政策的呼声日益高涨的情况下,剖析东南亚国家的黄箱政策是十分必要的.本文主要以越南,印尼,马来西亚,菲律宾为例,通过分析比较得出结论.     

琥珀的药学研究

在广泛检索文献的基础上。对琥珀传统药学、成分、药理及其现代临床的研究进行了概述,并探讨了琥珀的药学应用前景。     

Invasion and extinction in the west Indian ant fauna: evidence from the dominican amber

Of 37 genera and well-defined subgenera identified in the amber of the Dominican Republic (late Oligocene or early Miocene), 34 have survived somewhere in the New World tropics to the present, although the species studied thus far are extinct. Of the surviving genera and subgenera, 22 persist on Hispaniola. Fifteen genera and subgenera have colonized the island since amber times, restoring the number of genera and well-defined subgenera now present on Hispaniola to 37. A higher extinction rate has occurred in genera and subgenera that are either highly specialized or possess less colonizing ability, as evidenced by their restriction to the New World.     

Carnivorous fungi from Cretaceous amber

Carnivorous fungi dating back to the age of the dinosaurs have been found fossilized in circa-100-million-year-old amber. The fossil fungi used hyphal rings as trapping devices and are preserved together with their prey, small nematodes. The excellent preservation in amber allowed comparison with extant groups: On the basis of the mode of ring formation and the dimorphic mode of life, the fossils cannot be assigned to any recent carnivorous fungus, providing evidence that different groups occupied this ecological niche in the Cretaceous and that trapping devices were developed independently multiple times in the course of Earth history.     

Ultrastructure of 40-million-year-old insect tissue

Examination of the ultrastructure of preserved tissue in the abdomen of a fossil fly (Mycetophilidae: Diptera) entombed in Baltic amber revealed recognizable cell organelles. Structures that corresponded to muscle fibers, nuclei, ribosomes, lipid droplets, endoplasmic reticulum, and mitochondria were identified with the transmission electron microscope. Preservation was attributed to inert dehydration as well as the presence of compounds in the original sap which functioned as natural fixatives. This evidence of cell organelles in fossilized soft tissues represent an extreme form of mummification since Baltic amber is considered to have formed about 40 million years ago.     

核桃仁加工品(琥珀核桃仁、椒盐核桃仁)抗氧化活性的研究

本文对琥珀核桃仁、椒盐核桃仁以及未加工核桃仁的总酚含量、过氧化值和酸价进行了分析测定,用DPPH法和TBA法对以上3种核桃仁的95%乙醇提取物的抗氧化活性进行了分析比较。结果表明:与未加工的核桃仁相比,琥珀核桃仁和椒盐核桃仁的过氧化值和酸价略有升高;总酚含量分别下降了40%和26%;其95%乙醇提取物对DPPH自由基的清除能力也相应减少了44%和27%;用TBA法分析表明,在亚油酸脂质氧化第6d开始,琥珀核桃仁与椒盐核桃仁95%乙醇的提取物抑制脂质过氧化的作用明显减弱,而未加工核桃仁95%乙醇提取物的抑制作用持续稳定,与0.02%TBHQ相当。     

Lepidoptera in cretaceous amber

The discovery of the head capsule of a lepidopterous larva in Canadian amber of the Cretaceous period is the first fossil evidence of Lepidoptera before the Tertiary period.     

Bacteriophage T5 chromosome fractionation: genetic specificity of a DNA fragment

The bacteriophage T5 DNA fragments retained by a population of blended early complexes, formed under conditions of limited viral DNA transfer to host cells, appear to include only one of six tested cistrons. When complexes harboring wild-type fragments are infected with appropriate amber mutants, recombination occurs but apparently is not needed for productive infection.     

Gas bubbles in fossil amber as possible indicators of the major gas composition of ancient air

Gases trapped in Miocene to Upper Cretaceous amber were released by gently crushing the amber under vacuum and were analyzed by quadrupole mass spectrometry. After discounting the possibility that the major gases N(2), O(2), and CO(2) underwent appreciable diffusion and diagenetic exchange with their surroundings or reaction with the amber, it has been concluded that in primary bubbles (gas released during initial breakage) these gases represent mainly original ancient air modified by the aerobic respiration of microorganisms. Values of N(2)/(CO(2) + O(2)) for each time period give consistent results despite varying O(2)/CO(2) ratios that presumably were due to varying degrees of respiration. This allows calculation of original oxygen concentrations, which, on the basis of these preliminary results, appear to have changed from greater than 30 percent O(2) during one part of the Late Cretaceous (between 75 and 95 million years ago) to 21 percent during the Eocene-Oligocene and for present-day samples, with possibly lower values during the Oligocene-Early Miocene. Variable O(2) levels over time in general confirm theoretical isotope-mass balance calculations and suggest that the atmosphere has evolved over Phanerozoic time.     

Azure mutants: a type of host-dependent mutant of the bacteriophage f2

A new type of host-dependent mutant, azure mutant, of bacteriophage f2 has been isolated. Growth of these mutants was restricted specifically by amber suppressor genes in the host bacteria. Restriction of the formation of infective centers by different bacterial suppressor genes was 98 percent, 90 percent, and 70 percent with Su-3, Su-1, and Su-2 genes, respectively. Restriction, like suppression, was the dominant phenotype. The block in growth of the mutants occurred in an early stage of the infection cycle. Once infection was established, however, an infected cell produced approximately the same number of progeny phage as a cell without the suppressor genes did. It is proposed that the azure codon is the same as the amber codon (uracil, adenine, guanine) and that restriction results from improper termination of protein chains of the phage RNA polymerase. Similar mutants may exist in other systems.     

Comment on "A diverse assemblage of Late Cretaceous dinosaur and bird feathers from Canadian amber"

McKellar et al. (Reports, 16 September 2011, p. 1619) analyzed Late Cretaceous amber specimens from Canada and identified some filaments as dinosaurian protofeathers. We argue that their analysis and data do not provide sufficient evidence to conclude that such filaments are feather-like structures. Further investigation, including destructive sampling, must be carried out for more convincing conclusions.     

Changing the acceptor identity of a transfer RNA by altering nucleotides in a "variable pocket"

The specificity of tRNA(Arg) (arginine transfer RNA) for aminoacylation (its acceptor identity) were first identified by computer analysis and then examined with amber suppressor tRNAs in Escherichia coli. On replacing two nucleotides in tRNA(Phe) (phenylalanine transfer RNA) with the corresponding nucleotides from tRNA(Arg), the acceptor identity of the resulting tRNA was changed to that of tRNA(Arg). The nucleotides used in the identity transformation occupy a "variable pocket" structure on the surface of the tRNA molecule where two single-stranded loop segments interact. The middle nucleotide in the anticodon also probably contributes to the interaction, since an amber suppressor of tRNA(Arg) had an acceptor identity for lysine as well as arginine.     

多肉植物的水培试验

通过十种多肉植物的水培试验,探索不同类型的多肉植物的耐水能力,试验表明景天科伽蓝菜属、仙人掌科丝苇属、昙花属、金琥属均适合水培,光照、温度、养分影响其生根及长势,这为多肉植物水培产业化提供依据。     

The first mesozoic ants

Two worker ants preserved in amber of Upper Cretaceous age have been found in New Jersey. They are the first undisputed remains of social insects of Mesozoic age, extending the existence of social life in insects back to approximately 100 million years. They are also the earliest known fossils that can be assigned with certainty to aculeate Hymenoptera. The species, Sphecomyrma freyi, is considered to represent a new subfamily (Sphecomyrminae), more primitive than any previously known ant group. It forms a near-perfect link between certain nonsocial tiphiid wasps and the most primitive myrmecioid ants.     

Genetic coding: oligonucleotide coding for first six amino acid residues of the coat protein of R17 bacteriophage

Ribonucleic acids from the bacteriophage R17 and from R17 amber mutant AmB2 have been digested with ribonuclease T1. Of the products isolated, only one was different. It codes for the first six amino acid residues of the viral coat protein. The probable base sequence of the wild-type oligonucleotide is CpUpUpCpUpApApCpUpUpUpApCpUpCpApGp.     

Experience in a breeding program to create a flock of sur Karakul sheep of the new Surkhan Darya type

To increase the production of sur karakul fur of the Surkhan Darya intrabreed type, regularities in the inheritance of colors in progeny have been studied. Both with homogeneous and heterogeneous breeding of ewes and stud rams of bronze, amber, and platinum colors, a high heredity of bronze and platinum colors is noted. The color of rams has a greater effect on inheritance of colors.     

Pyrrolysine encoded by UAG in Archaea: charging of a UAG-decoding specialized tRNA

Pyrrolysine is a lysine derivative encoded by the UAG codon in methylamine methyltransferase genes of Methanosarcina barkeri. Near a methyltransferase gene cluster is the pylT gene, which encodes an unusual transfer RNA (tRNA) with a CUA anticodon. The adjacent pylS gene encodes a class II aminoacyl-tRNA synthetase that charges the pylT-derived tRNA with lysine but is not closely related to known lysyl-tRNA synthetases. Homologs of pylS and pylT are found in a Gram-positive bacterium. Charging a tRNA(CUA) with lysine is a likely first step in translating UAG amber codons as pyrrolysine in certain methanogens. Our results indicate that pyrrolysine is the 22nd genetically encoded natural amino acid.