@phdthesis{Wicker2004,
  author    = {Wicker, Monika},
  title     = {Vergleichende Analyse zwischen Candida albicans und Candida dubliniensis unter besonderer Ber{\"u}cksichtigung des Transkriptionsfaktors Rim101},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-16694},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {C.dubliniensis kann, wie auch die nahe verwandte Spezies C.albicans, als Antwort auf eine Reihe von Umweltfaktoren von der Hefeform in echtes filament{\"o}ses Wachstum {\"u}bergehen. Bei der Regulation des pH-abh{\"a}ngigen Dimorphismus von C.dubliniensis spielt, wie bei verschiedenen anderen Pilzspezies der Zinkfinger-Transkriptionsfaktor Rim101 eine zentrale Rolle. Dieser weist mit 85\% zwar eine im Speziesvergleich geringe Aminos{\"a}ure-identit{\"a}t zu C.albicans-Rim101 auf, zeigt jedoch die gleiche pH-abh{\"a}ngige Expression wie C.albicans-RIM101, ist in C.albicans funktionell aktiv und kann die typischen Defekte einer C.albicans-rim101-Nullmutante komplementieren. C.dubliniensis-Rim101 ist zudem beteiligt an der Regulation des Wachstums bei 45°C und der Kolonief{\"a}rbung auf CHROM agar-Candida, zwei Eigenschaften, in denen sich C.albicans und C.dubliniensis unterscheiden. Ursache f{\"u}r diese speziesspezifische Merkmalsauspr{\"a}gung ist die bei C.dubliniensis deutlich st{\"a}rkere Expression von RIM101. Ein weiterer ph{\"a}notypischer Unterschied zwischen C.albicans und C.dubliniensis betrifft mit der F{\"a}higkeit zu Filamentierung und invasivem Wachstum zwei f{\"u}r C.albicans nachgewiesenermaßen wichtige Virulenzfaktoren. Auf Kochblutagar, nach 24 - 48-st{\"u}ndiger Inkubation bei 37°C und 5\% CO2, bildet C.dubliniensis glatte, weiß-gl{\"a}nzende, scharf begrenzte halbkugelf{\"o}rmige Kolonien, w{\"a}hrend C.albicans-Kolonien eine rauhe, grau erscheinende Oberfl{\"a}che aufweisen und mit Ausl{\"a}ufern in den umgebenden Agar einwachsen. Ausl{\"o}send f{\"u}r die ausgepr{\"a}gte Filamentierung von C.albicans ist das additive Zusammenwirken von erh{\"o}htem CO2-Gehalt, erh{\"o}hter Temperatur und einem noch nicht endg{\"u}ltig identifizierten Bestandteil des Kochblutagars. Mit einer Sensitivit{\"a}t von 95,8\% und einer Spezifit{\"a}t von 100\% eignet sich dieses Verfahren auch als einfacher diagnostischer Test. Auf molekularer Ebene sind Efg1 und Cph1 an der Filamentierungsausl{\"o}sung beteiligt, wobei Efg1 aber eine wesentlich gr{\"o}ßere Bedeutung zukommt. Rim101 scheint keinen Einfluss zu haben.},
  language  = {de}
}
@article{HuangDingRoelfsemaetal.2021,
  author    = {Huang, Shouguang and Ding, Meiqi and Roelfsema, M. Rob G. and Dreyer, Ingo and Scherzer, S{\"o}nke and Al-Rasheid, Khaled A. S and Gao, Shiqiang and Nagel, Georg and Hedrich, Rainer and Konrad, Kai R.},
  title     = {Optogenetic control of the guard cell membrane potential and stomatal movement by the light-gated anion channel GtACR1},
  series = {Science Advances},
  volume    = {7},
  journal   = {Science Advances},
  number    = {28},
  doi       = {10.1126/sciadv.abg4619},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260925},
  year      = {2021},
  abstract  = {Guard cells control the aperture of plant stomata, which are crucial for global fluxes of CO\(_2\) and water. In turn, guard cell anion channels are seen as key players for stomatal closure, but is activation of these channels sufficient to limit plant water loss? To answer this open question, we used an optogenetic approach based on the light-gated anion channelrhodopsin 1 (GtACR1). In tobacco guard cells that express GtACR1, blue- and green-light pulses elicit Cl\(^-\) and NO\(_3\)\(^-\) currents of -1 to -2 nA. The anion currents depolarize the plasma membrane by 60 to 80 mV, which causes opening of voltage-gated K+ channels and the extrusion of K+. As a result, continuous stimulation with green light leads to loss of guard cell turgor and closure of stomata at conditions that provoke stomatal opening in wild type. GtACR1 optogenetics thus provides unequivocal evidence that opening of anion channels is sufficient to close stomata.},
  language  = {en}
}
@phdthesis{Weidenmueller2001,
  author    = {Weidenm{\"u}ller, Anja},
  title     = {From individual behavior to collective structure},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-2448},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2001},
  abstract  = {The social organization of insect colonies has long fascinated naturalists. One of the main features of colony organization is division of labor, whereby each member of the colony specializes in a subset of all tasks required for successful group functioning. The most striking aspect of division of labor is its plasticity: workers switch between tasks in response to external challenges and internal perturbations. The mechanisms underlying flexible division of labor are far from being understood. In order to comprehend how the behavior of individuals gives rise to flexible collective behavior, several questions need to be addressed: We need to know how individuals acquire information about their colony's current demand situation; how they then adjust their behavior according; and which mechanisms integrate dozens or thousands of insect into a higher-order unit. With these questions in mind I have examined two examples of collective and flexible behavior in social bees. First, I addressed the question how a honey bee colony controls its pollen collection. Pollen foraging in honey bees is precisely organized and carefully regulated according to the colony's needs. How this is achieved is unclear. I investigated how foragers acquire information about their colony's pollen need and how they then adjust their behavior. A detailed documentation of pollen foragers in the hive under different pollen need conditions revealed that individual foragers modulate their in-hive working tempo according to the actual pollen need of the colony: Pollen foragers slowed down and stayed in the hive longer when pollen need was low and spent less time in the hive between foraging trips when pollen need of their colony was high. The number of cells inspected before foragers unloaded their pollen load did not change and thus presumably did not serve as cue to pollen need. In contrast, the trophallactic experience of pollen foragers changed with pollen need conditions: trophallactic contacts were shorter when pollen need was high and the number and probability of having short trophallactic contacts increased when pollen need increased. Thus, my results have provided support for the hypothesis that trophallactic experience is one of the various information pathways used by pollen foragers to assess their colony's pollen need. The second example of collective behavior I have examined in this thesis is the control of nest climate in bumble bee colonies, a system differing from pollen collection in honey bees in that information about task need (nest climate parameters) is directly available to all workers. I have shown that an increase in CO2 concentration and temperature level elicits a fanning response whereas an increase in relative humidity does not. The fanning response to temperature and CO2 was graded; the number of fanning bees increased with stimulus intensity. Thus, my study has evidenced flexible colony level control of temperature and CO2. Further, I have shown that the proportion of total work force a colony invests into nest ventilation does not change with colony size. However, the dynamic of the colony response changes: larger colonies show a faster response to perturbations of their colony environment than smaller colonies. Thus, my study has revealed a size-dependent change in the flexible colony behavior underlying homeostasis. I have shown that the colony response to perturbations in nest climate is constituted by workers who differ in responsiveness. Following a brief review of current ideas and models of self-organization and response thresholds in insect colonies, I have presented the first detailed investigation of interindividual variability in the responsiveness of all workers involved in a collective behavior. My study has revealed that bumble bee workers evidence consistent responses to certain stimulus levels and differ in their response thresholds. Some consistently respond to low stimulus intensities, others consistently respond to high stimulus intensities. Workers are stimulus specialists rather than task specialists. Further, I have demonstrated that workers of a colony differ in two other parameters of responsiveness: response probability and fanning activity. Response threshold, response probability and fanning activity are independent parameters of individual behavior. Besides demonstrating and quantifying interindividual variability, my study has provided empirical support for the idea of specialization through reinforcement. Response thresholds of fanning bees decreased over successive trials. I have discussed the importance of interindividual variability for specialization and the collective control of nest climate and present a general discussion of self-organization and selection. This study contributes to our understanding of individual behavior and collective structure in social insects. A fascinating picture of social organization is beginning to emerge. In place of centralized systems of communication and information transmission, insect societies frequently employ mechanisms based upon self-organization. Self-organization promises to be an important and unifying principle in physical, chemical and biological systems.},
  subject      = {Hummeln},
  language  = {en}
}