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  • 1
    ISSN: 1420-9098
    Keywords: Castes ; reproductive intercastes ; supplementary reproductives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Females ofTechnomyrmex albipes consist of winged queens, intercastes and workers. In established colonies, reproduction is performed by many intercastes (wingless females which have intermediate phenotypes between queen and worker characters). Dissection and morphological examination revealed that intercastes had a spermatheca, but workers did not. Intercastes can be divided into three classes: major intercastes with three ocelli, medium intercastes with one ocellus, and minor intercases without ocelli. Workers have no ocelli. The thoracic structure of intercastes gradually becomes more complex from minors to majors. The body size of intercastes gradually increases from minors to majors, and so does the number of overioles. The body size distributions of minor intercastes and workers overlap considerably, but the distributions of ovariole numbers overlap less. Winged queens had distinctly larger body sizes, more ovarioles and larger spermathecae than intercastes. Most intercastes were inseminated with developed ovaries and appeared to reproduce. The caste system and reproductive division of labour inT. albipes is compared to those of ant species in which permanently wingless females reproduce.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 35 (1988), S. 321-340 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Das Nestplatzwechselverhalten der königinnenlosen japanischen AmeisePristomyrmex pungens (Myrmicinae) wurde an zwei Stellen (A und Y) im Stadtgebiet von Nagoya untersucht. Diese Art legt keine wohlausgebauten unterirdischen Nester an, sondern wechselt statt dessen häufig ihren Nistplatz. Die mittlers Aufenhaltsdauer an einem Nestplatz, betrug 17,4 Tage an Stelle A und 17.7 Tage an Stelle Y. Dies ist kürzer als bei anderen Ameisen, die in klimatisch ähnlichen Gebieten leben. Es gab keine erkennbaren jahreszeitlichen Anderungen in der Häufigkeit des Umziehens während der Aktivitätsphase der Ameisen, jedoch schwankeb die Nestplatzpräferenzen saisonal. Der Nestwechsel folgt keinem zyklischen Rhythmus. Trotz der häufigen Nestwechsel waren die Nester stets gleichmäßig verteilt. Die mittlers Umzugsdistanzen betrugen an Platz A 6,8 m und an Platz Y 3,9 m. Zwei aufei nanderfolgende Umzüge tendierten dazu, in entgegengesetzte Richtungen zu führen. Die Umzugsrichtung wurde nicht durch die Distanz zu einem Nachbarnest beeinflußt. Umzüge fanden in der Regel kleinräumig statt. Die Zeit, die eine Kolonie für den Umzug benötigte, wurde auf 20 Stunden geschätzt. Der Anteil an polydomen Kolonien betrug an Stelle A 13,7 und an Stelle Y 2,3% (fakultative Polydomie). Der Anteil der Zweignester pro Kolonie zeigt im Sommer eine zunehmende Tendenz. Künstliche Entfernung von Pflanzen, auf denen die Ameisen Honigtau von Blattläusen sammleten, löste Nestwechsel aus. Es wird diskutiert, welche adaptive und ökologische Bedeutung der Nestwechsel bei dieser Ameise besitzt.
    Notes: Summary Nest relocation behavior in the Japanese queenless ant,Pristomyrmex pungens (Myrmicinae), was investigated in two study fields (site A and site Y) in Nagoya City. This species did not construct elaborate subterranean nests but frequently relocated its nests instead. Mean nest longevities were 17.4 days in site A and 15.7 days in site Y, shorter than those of other ants living in similar climatic regions. There was no apparent seasonal change in the frequency of nest relocation throughout the ant's active season, but nest site preference changed seasonally. Nest relocations did not follow a cyclical pattern. Despite the frequent nest relocations, nests were always distributed uniformly. Mean nest relocation distances were 6.8 m in site A and 3.9 m in site Y. Two consecutive nest relocations tended to be in opposite directions. The direction of nest movement was not affected by the distance to a neighbouring nest. Nest movements were usually confined within a small area. Time spent by a colony to relocate its nest was estimated as 20 hr. The proportion of polydomous colonies was 13.7e% in site A and 2.3% in site Y (facultative polydomy). Number of nests per colony tended to increase in summer. Artificial removal of weeds on which workers were collecting aphids' elicited nest relocation. Adaptive and ecological significances of the nest relocation of this ant were discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 42 (1995), S. 333-336 
    ISSN: 1420-9098
    Keywords: Parthenogenesis ; worker reproduction ; thelytoky ; Cerapachyinae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Groups of virginCerapachys biroi workers produced females (workers) in the laboratories. This is the first report of thelytoky in Cerapachyinae.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1420-9098
    Keywords: Hypoponera bondroiti ; ergatoid male ; intercaste ; dimorphism ; mating strategy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We studied the reproductive behavior of the ponerine antHypoponera bondroiti from Okinawa, Japan. This species has dimorphic wingless ergatoid males (major and minor), dimorphic reproductive females (alate queens and wingless reproductive intercastes), and workers. Workers have neither ovarioles nor spermatheca. Major ergatoid males are the largest colony members. Two major males fought one another in the nest until one disappeared, leaving the other to occupy the nest chambers where queens emerge and mate. Minor ergatoid males also fought one another, although they seemed to be less pugnacious, resulting in occasional cohabitation of multiple minor males in the same nest chamber. Major males never attacked minor ones, allowing them to coexist in the same nest chamber. Minor males seemed to mimic females. Both major and minor males mated with both alate queens and intercastes within the nest. After mating, some alate queens shed their wings and remained in the nest, while the others left the nest for dispersal in the laboratory. Intercastes remained in the nest.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1420-9098
    Keywords: Ponerinae ; reproduction ; dominance ; aggression ; cannibalism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Queens do not exist inDiacamma sp. from Japan, and a single worker (“gamergate”) mates and monopolizes reproduction in each colony. We isolated small groups of workers without the gamergate, and confirmed that after 7–15 days many workers were able to oviposit (Tab. 1). These egg-laying individuals engage in stereotyped attacks towards each other. In six groups of individually marked workers (Tabs. 3 to 7), the pattern of aggressive interactions always indicated that one worker was dominant. She usually initiated a large number of attacks, but was herself never attacked. This dominant worker (“alpha”) also ate the eggs just laid by others. There was no linear dominance hierarchy, although a second highest-ranking worker could be recognized (she was only attacked by alpha). When these workers were dissected 4–6 weeks after being orphaned, only the alpha worker had active ovaries; other individuals that had been observed to oviposit earlier exhibited resorbed ovaries. Dissection of another 12 orphaned groups, kept together for different periods of time (Tab. 2), confirmed that one dominant worker is able to suppress the ovarian activity of all others in her group. We discuss how these aggressive interactions also function to regulate the production of males in other contexts, even when the gamergate is present. This aggression is separate, however, from another competitive interaction, mutilation of the gemmae, that functions as a control of mating activity in this species.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0428
    Keywords: Type 1 (insulin-dependent) diabetes ; HLA ; auto-antibodies ; islet cell antibody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary HLA phenotypes and haplotypes in relation to organ-specific autoantibody responses were studied in 82 Japanese patients with Type 1 (insulin-dependent) diabetes. HLA-DRw9 antigen and HLA phenotype of DRw9/X (X: not DR4) were increased in patients with organ-specific autoantibodies other than islet cell antibody (CP〈0.02, RR=4.02 and p〈0.05, RR=2.30, respectively); whereas HLA-DR4 antigen and HLA phenotype of DR4/X (X: not DRw9) were increased in those without the autoantibodies (CP〈0.001, RR=3.95 and p〈0.01, RR=2.46, respectively). HLA haplotype of Bw61-DRw9 was increased in patients with the autoantibodies (p〈0.005, RR=4.94), and HLA haplotype of Bw54-DR4 was increased in those without the autoantibodies (p〈0.001, RR=5.52). The relative risk of HLA-DR4/DRw9 was the highest among all HLA-DR phenotypes or genotypes in patients either with or without the autoantibodies. No association was, however, found between the incidence of islet cell antibody and HLA-DR phenotypes. These findings suggest that Type 1 diabetes among Japanese is immunogenetically heterogeneous as is Type 1 diabetes among Caucasians; and the differences in HLA-association of Type 1 diabetes among ethnic groups might give a clue to understanding of a role of HLA-antigens in the development of Type 1 diabetes.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0428
    Keywords: Glucagon ; insulin ; somatostatin ; streptozotocin ; sympathetic nerve ; diabetic rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Changes in glucagon, insulin and somatostatin secretion induced by electrical splanchnic nerve stimulation were examined in rats treated with streptozotocin as neonates and as adults. In order to study the direct neural effects we used the isolated perfused rat pancreas with intact left splanchnic nerve in vitro. In normal rats splanchnic nerve stimulation causes significant decreases in insulin (30–40%) and somatostatin (30–50%) secretion at both 16.7 mmol/l and 1 mmol/l glucose concentrations. In the neonatal streptozotocin-diabetic rats splanchnic nerve stimulation at 16.7 mmol/l glucose decreased insulin secretion (14%) further than in the control rats (30%), however, somatostatin secretion did not decrease to the same extent. Similar results were also observed at the low (1 mmol/l) glucose concentration. On the other hand, percent decreases of insulin and somatostatin secretion induced by splanchnic nerve stimulation in the streptozotocin-diabetic rats were similar to the values observed in the normal control rats. The glucagon secretion in response to splanchnic nerve stimulation at 16.7 mmol/l glucose from pancreatic Alpha cells in both types of induced diabetes is exaggerated, and the degree of exaggeration seems to parallel the severity of the hyperglycaemia. However, the splanchnic nerve stimulation-induced glucagon secretion at 1 mmol/l glucose was impaired in the streptozotocin-diabetic rats, but not in the neonatal streptozotocin-diabetic rats. These data suggest that the sensitivity of diabetic Alpha and Delta cells to sympathetic neural activation are blunted, whereas the sensitivity of Beta cells is enhanced in the diabetic animal model.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 13 (1986), S. 273-280 
    ISSN: 1432-1017
    Keywords: Bacteriorhodopsin ; blue membrane ; purple membrane films ; electric field-induced states ; electric dichroism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Electric field-induced absorption changes of bacteriorhodopsin were studied with different samples of purple membranes which were prepared as randomly oriented and electrically oriented films of purple as well as cation-depleted blue bacteriorhodopsin. The absorption changes were proportional to the square of the field strength up to ≈300 kV/cm. The electric field from the intracellular side to the extracellular side of the purple bacteriorhodopsin induces a spectrum change, resulting in a spectrum similar to that of the cation-depleted blue bacteriorhodopsin. When the field was removed, the purple state was regenerated. The blue state was mainly affected by an electric field in the opposite direction, suggesting a reversible interaction with the Schiff's base bond of the retinal. Since the field-induced reaction of bacteriorhodopsin was observed in the presence of a concomitant steady ion flux, it is assumed that the generation of a local diffusion potential may play an important role in these spectral reactions. Although the fragments were fixed in the dried film, electric dichroism was observed. The dichroic contribution of the total absorbance change was about 15%. The angular displacement of the retinal transition moment was calculated to be 1.5° toward the membrane normal.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 15 (1987), S. 231-236 
    ISSN: 1432-1017
    Keywords: Bacteriorhodopsin ; blue membrane ; purple membrane ; electric dichroism ; cation binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Blue bacteriorhodopsin was prepared by electrodialysis, cation-exchange chromatography and acidification. The electrooptical properties of these preparations compared to those of the native purple bacteriorhodopsin suggest that the blue bacteriorhodopsin has a smaller induced dipole moment than the native purple bacteriorhodopsin and that bound cations in the native bacteriorhodopsin stabilize the protein conformation in the membrane. Purple bacteriorhodopsin was regenerated by addition of potassium, magnesium or ferric ions to blue bacteriorhodopsin. Both spectrscopically and electrooptically the potassium- and ferric-regenerated samples are different from the native purple state. Although the magnesium-regenerated sample is spectroscopically similar to the native purple bacteriorhodopsin, the electrooptical properties are rather similar to those of the cation-depleted blue sample, suggesting that it is very difficult to re-stabilize protein structures once cations are depleted.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 15 (1988), S. 329-337 
    ISSN: 1432-1017
    Keywords: Bacteriorhodopsin ; blue membrane ; purple membrane films ; electric-field-induced states ; dielectric dispersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Electric field induced conformational changes of bacteriorhodopsin were studied in six types of dried film (randomly and electrically oriented membranes of purple as well as cation-depleted blue bacteriorhodopsin) by measuring the frequency dependence of the optical absorbance change and the dielectric dispersion and absorption. For the purple bacteriorhodopsin the optical absorbance change induced by alternating rectangular electric fields of ±300 kV/cm altered the sign twice in the frequency range from 0.001 Hz to 100 kHz (around 0.03 Hz and 100 kHz), indicating that the electric field induced conformational change in these samples consists of, at least, three steps. Similarly, it was found for the blue bacteriorhodopsin that at least two steps are involved. In accord with optical measurements, the dielectric behaviour due to alternating sinusoidal electric fields of±6kV/cm in the frequency range from 10 Hz to 10 MHz showed two broad dispersion/absorption regions, one below 1 kHz and the other around 10–100 kHz. This suggests that the conformational change of bacteriorhodopsin is also reflected by its dielectrical properties and that it is partially induced at 6 kV/cm. Including previous results obtained by analysis of the action of DC fields on purple membrane films, a model for a field-induced cyclic reaction for purple as well as blue bacteriorhodopsin is proposed. In addition it was found that there are electrical interactions among purple membrane fragments in dried films.
    Type of Medium: Electronic Resource
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