Fast axonal transport in extruded axoplasm from squid giant axon

Development of video-enhanced contrast-differential interference contrast for light microscopy has permitted study of both orthograde and retrograde fast axonal transport of membranous organelles in the squid giant axon. This process was found to continue normally for hours after the axoplasm was extruded from the giant axon and removed from the confines of the axonal plasma membrane. It is now possible to follow the movements of the full range of membranous organelles (30-nanometer vesicles to 5000-nanometer mitochondria) in a preparation that lacks a plasma membrane or other permeability barrier. This observation demonstrates that the plasma membrane is not required for fast axonal transport and suggests that action potentials are not involved in the regulation of fast transport. Furthermore, the absence of a permeability barrier surrounding the axoplasm makes this an important model for biochemical pharmacological, and physical manipulations of membranous organelle transport.     

Aplysia californica: analysis of nuclear DNA in individual nuclei of giant neurons

The nuclei of the giant neurons of the marine mollusk Aplysia californica can contain more than 0.2 microgram of DNA. This is more than 200,000 times as much DNA as the haploid amount found in Aplysia sperm. On the basis of nuclear DNA content, the giant neurons R-2, P-1, and L-6 of adult animals can each be divided into at least two populations. The mean DNA content of these two populations (0.067 and 0.131 microgram of DNA) are approximately related by a factor of 2. This suggests that much and perhaps all of the genome replicates repeatedly (up to 16 times) during the growth and development of these neurons and that each replication is synchronous. The enormous amount of DNA in these cells opens up the possibility of characterizing the DNA and other constituents of chromatin from individual but phenotypically different neurons.     

Homing in the ant Cataglyphis bicolor

Cataglyphis bicolor, an ant widely distributed in North Africa and the Near East, orient to the sun as well as to visual patterns of the environment. These two mechanisms can be separated. Foraging ants (hunters) orient to terrestrial cues as long as possible, and only after these have become ineffective do they switch over to the menotactical sun orientation. In the digging individuals, however, the visual knowledge of locality is significantly inferior to that of the hunters. Diggers vary considerably in size, but hunters belong to the largest size group. In addition, the largest and smallest individuals orient differently toward black and white areas and stripe patterns.     

Homing in the harvester ant Pogonomyrmex badius

During homing, the harvester ant Pogonomyrmex badius orients both to the sun and to chemical cues. Visual patterns are generally the less important. Trails laid from the secretion of Dufour's gland comprise the main chemical homing signal. This orientation mechanism assists foraging workers to return precisely to their own nests even when the nest populations are dense.     

Tournaments and slavery in a desert ant

Many species of ants engage in physical fighting when territorial borders are challenged. In contrast, colonies of the honeypot ant species Myrmecocystus mimicus conduct ritualized tournaments, in which hundreds of ants perform highly stereotyped display fights. Opposing colonies summon their worker forces to the tournament area by means of an alarm-recruitment system. When one colony is considerably stronger than the other, the tournament quickly ends, and the weaker colony is raided and its ants "enslaved." This is the first example of intraspecific slavery recorded in ants.     

Oxygen isotopes and the moon-forming giant impact

We have determined the abundances of 16O, 17O, and 18O in 31 lunar samples from Apollo missions 11, 12, 15, 16, and 17 using a high-precision laser fluorination technique. All oxygen isotope compositions plot within +/-0.016 per mil (2 standard deviations) on a single mass-dependent fractionation line that is identical to the terrestrial fractionation line within uncertainties. This observation is consistent with the Giant Impact model, provided that the proto-Earth and the smaller impactor planet (named Theia) formed from an identical mix of components. The similarity between the proto-Earth and Theia is consistent with formation at about the same heliocentric distance. The three oxygen isotopes (delta17O) provide no evidence that isotopic heterogeneity on the Moon was created by lunar impacts.     

遗传算法和蚁群算法融合求解TSP

文章将遗传算法和蚁群算法融合为一体,在此基础上,分别对遗传算法和蚁群算法中的遗传算法中的交叉长度发生变化、种群更新、蚁群算法信息素保留率和信息素自动更新进行了改进。同时给出一种信息素更新模型,最后通过对TSP的51个城市的仿真计算,表明将遗传算法和蚁群算法融合为一体效果较好。     

Oceili: a celestial compass in the desert ant cataglyphis

In addition to multifaceted lateral compound eyes, most insects possess three frontal eyes called ocelli. Each ocellus has a single lens, as does the vertebrate eye. The ocelli of some flying insects, locusts and dragonflies, have been shown to function as horizon detectors involved in the visual stabilization of course. In a walking insect, the desert ant Cataglyphis, it is now shown that the ocelli can read compass information from the blue sky. When the ant's compound eyes are occluded and both sun and landmarks are obscured, the ocelli, using the pattern of polarized light in the sky as a compass cue, help in guiding the ant back home.     

中国蚂蚁资源研究进展

蚂蚁是地球上分布最广、种类和数量最多的社会性昆虫,也是一类食用和药用资源昆虫.从分类研究文献、区系分布调查、生物学特征、生态学、细胞分子生物学、食用和药用价值以及蚂蚁资源的开发利用与保护等方面论述中国蚂蚁的研究进展.     

Effectiveness of growing the giant filbert in Dagestan

The structure of the cost of preparing the soil and growing the giant filbert under conditions of Dagestan is given. The payback of the cost of creating orchards at wholesale and retail prices, sales proceeds, and profit are shown.     

捕捉和模拟Windows环境中鼠标和键盘操作的方法

提出在Windows系统范围内,且不影响其它进程的前提下,实现捕捉鼠标和键盘操作及其事后模拟过程的方法;并给出了程序的关键片段.     

Interspecific hybridization and caste specificity of protein in fire ant

One natural population of fire ant in Texas was found to be a hybrid between Solenopsis geminata and S. xyloni. Evidence from isozyme studies and breeding experiments is provided to demonstrate interspecific hybridization in ants. In this hybrid population, all worker ants have both parental types of nicotinamide adenine dinucleotide-malate dehydrogenase isozymes, but 95 percent of queens possess only the maternal type.     

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.     

Bose-Einstein condensation of microcavity polaritons in a trap

We have created polaritons in a harmonic potential trap analogous to atoms in optical traps. The trap can be loaded by creating polaritons 50 micrometers from its center that are allowed to drift into the trap. When the density of polaritons exceeds a critical threshold, we observe a number of signatures of Bose-Einstein condensation: spectral and spatial narrowing, a peak at zero momentum in the momentum distribution, first-order coherence, and spontaneous linear polarization of the light emission. The polaritons, which are eigenstates of the light-matter system in a microcavity, remain in the strong coupling regime while going through this dynamical phase transition.     

河南洛阳地区蚂蚁种类和分布调查

蚂蚁是土壤中大型动物的优势类群,种群数量庞大,分布较广。通过调查获得洛阳地区蚂蚁包括5亚科,13属,31种。优势种为铺道蚁、粗面收获蚁、日本弓背蚁,且不同生境、不同地域内的蚂蚁种类和分布都有差异。根据调查资料分析了该地区6种生境中蚂蚁种群的结构及多样性特征,以及人为干扰和生境异质性对蚂蚁群落的影响,结果表明:6种生境中蚂蚁群落种类、组成和多样性等指标均不相同。人为干扰越强的生境,蚂蚁种群多样性指数越低;生境质量和异质性越高,蚂蚁种群多样性指数越高。