scholarly journals Octopamine drives honeybee thermogenesis

2021 ◽  
Author(s):  
Sinan Kaya-Zeeb ◽  
Lorenz Engelmayer ◽  
Jasmin Bayer ◽  
Heike Bähre ◽  
Roland Seifert ◽  
...  
Keyword(s):  
Selective Pressure ◽  
Cold Climates ◽  
Physiological Plasticity ◽  
Worldwide Distribution ◽  
Environment Adaptation ◽  
Octopamine Receptors ◽  
Cold Shivering ◽  
Flight Muscles ◽  
Necessary And Sufficient ◽  
Shivering Thermogenesis

In times of environmental change species have two options to survive: they either relocate to a new habitat or they adapt to the altered environment. Adaptation requires physiological plasticity and provides a selection benefit. In this regard, the Western honeybee (Apis mellifera) protrudes with its thermoregulatory capabilities, which enables a nearly worldwide distribution. Especially in the cold, shivering thermogenesis enables foraging as well as proper brood development and thus survival. In this study, we present octopamine signaling as a neurochemical prerequisite for honeybee thermogenesis: we were able to induce hypothermia by depleting octopamine in the flight muscles. Additionally, we could restore the ability to increase body temperature by administering octopamine. Thus we conclude, that octopamine is necessary and sufficient for thermogenesis. Moreover, we show that these effects are mediated by β octopamine receptors. The significance of our results is highlighted by the fact the respective receptor genes underlie enormous selective pressure due to adaptation to cold climates. Finally, octopamine signaling in the service of thermogenesis might be a key strategy to survive in a changing environment.

Neural Control of Fibrillar Muscles in Bees During Shivering and Flight

1991 ◽  
Vol 159 (1) ◽  
pp. 419-431 ◽  
Author(s):  
HARALD ESCH ◽  
FRANZ GOLLER
Keyword(s):  
Muscle Activity ◽  
Neural Control ◽  
Stretch Activation ◽  
Warm Up ◽  
Modes Of Action ◽  
Flight Muscles ◽  
First Time ◽  
Longitudinal Muscles ◽  
Shivering Thermogenesis ◽  
Muscle Potential

The big indirect flight muscles in the thorax of honeybees and bumblebees show two modes of action: they contract with ‘conventional’ twitches in response to slowly repeated muscle potentials and go into tetanus at higher muscle potential frequencies. They can also contract much faster when quickly stretched (stretch activation). We observed contractions of DV (dorsoventral) and DL (dorsal longitudinal) muscles optically with the help of a tiny mirror glued to the scutellum. We noticed that DL muscles contracted much more than DV muscles during pre-flight warmup. During warm-up, muscle potential frequencies in DL muscles were higher than in DV muscles (DL frequency/DV frequency =1.3), whereas during flight the ratio reversed (DL/DV=0.8). The scutal fissure was completely closed during shivering warm-up, apparently because the DL muscles shortened as much as they could. As a consequence, fast antagonistic stretching was not possible. However, the scutal fissure oscillated between wide open and closed during flight, and antagonists could stretch each other quickly. Flight was started by highly synchronized ‘conventional’ contractions of many muscle elements in DV muscles. Antagonistic stretch-activation during flight led to faster shortening than during shivering warm-up and synchronized all activated muscle elements to produce maximal contractions. The indirect flight muscles of bumblebees were in tetanic contractions during shivering warm-up over the whole range of temperatures between 8 and 36°C. These tetanic contractions probably prevented other researchers from observing mechanical muscle activity. Our results, which for the first time allow us to detect tetanic contractions directly, make it very improbable that non-shivering thermogenesis occurs in bumblebees, as has been proposed previously.

Infection strategies of retroviruses and social grouping of domestic cats

1997 ◽  
Vol 75 (12) ◽  
pp. 1994-2002 ◽  
Author(s):  
Emmanuelle Fromont ◽  
Franck Courchamp ◽  
Dominique Pontier ◽  
Marc Artois
Keyword(s):  
Selective Pressure ◽  
Leukemia Virus ◽  
Host Population ◽  
Feline Leukemia Virus ◽  
Domestic Cats ◽  
Worldwide Distribution ◽  
Transmission Modes ◽  
Social Grouping ◽  
Low Prevalence ◽  
The Impact

It is thought that parasites may exert selective pressure on the social structure of host populations. We compared the impact of feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV), two retroviruses commonly found in domestic cats (Felis catus). Because of low transmissibility and virulence, both infections have a worldwide distribution and low prevalence. Transmission modes differ: FIV is transmitted only through biting, while FeLV transmission occurs by biting, licking, grooming, and sharing food and from mother to fetus. FeLV is also more pathogenic than FIV. We compared FIV and FeLV prevalence and risk factors within five populations of cats. FIV infection occurred almost exclusively among adult male cats fighting to acquire and maintain dominant status. Classes at risk for FeLV infection included sexually intact cats allowed to roam freely. The impact of FeLV on host population growth was greater than that of FIV but varied among populations. Our results show that FIV is favoured by individual aggressiveness and a hierarchical social system, while FeLV is more prevalent among socially active cats. FeLV may constitute a source of selective pressure against numerous amicable contacts, particularly in urban cat populations, where aggression among individuals is reduced.

The Role of Cyclic AMP in the Octopaminergic Modulation of Flight Muscle in the Locust

1991 ◽  
Vol 161 (1) ◽  
pp. 423-438
Author(s):  
MATTHEW D. WHIM ◽  
PETER D. EVANS
Keyword(s):  
Cyclic Amp ◽  
Flight Muscle ◽  
Schistocerca Gregaria ◽  
Phosphodiesterase Inhibitors ◽  
Motor Units ◽  
Blocking Agent ◽  
Receptor Activation ◽  
Octopamine Receptors ◽  
Flight Muscles

The role of cyclic AMP in the octopaminergic modulation of the dorsal longitudinal flight muscles of the locust Schistocerca gregaria has been investigated. Several techniques have been used to elevate cyclic AMP levels in this tissue by mechanisms that bypass the receptor activation stage. These include the use of phosphodiesterase inhibitors to block the metabolism of cyclic nucleotides, the use of forskolin, the diterpene activator of adenylate cyclase, and the direct application of permeable and phosphodiesterase-resistant analogues of cyclic AMP. All these approaches can be shown to mimic the modulatory effects of octopamine on the flight muscle. Surprisingly, the phosphodiesterase inhibitors used were not able to potentiate the actions of octopamine on this preparation. Octopamine increases cyclic AMP levels in a similar fashion in all five motor units of this muscle, an effect that is selectively blocked by phentolamine, an α-adrenergic blocking agent that blocks octopamine receptors in other preparations. In addition, stimulation of the dorsal unpaired median neurone to the dorsal longitudinal flight muscles (DUMDL) results in a frequency-dependent increase in cyclic AMP levels in the muscle that is also blocked by phentolamine. The data presented suggest that the octopamine-mediated modulation of neurally evoked tension in this muscle is brought about by a mechanism that involves an increase in cyclic AMP levels in the tissue.

scholarly journals Temperature drives the evolution and global distribution of avian eggshell colour

2019 ◽  
Author(s):  
Phillip A. Wisocki ◽  
Patrick Kennelly ◽  
Indira Rojas Rivera ◽  
Phillip Cassey ◽  
Daniel Hanley
Keyword(s):  
Global Climate Change ◽  
Phylogenetic Diversity ◽  
Selective Pressure ◽  
Global Climate ◽  
Cold Climates ◽  
Trade Off ◽  
Thermal Limits ◽  
Show Evidence ◽  
Eggshell Colour ◽  
Require Data

The survival of a bird’s egg depends upon their ability to maintain within strict thermal limits. Avian eggshell colours have long been considered a phenotype that can help them stay within these thermal limits, with dark eggs absorbing heat more rapidly than bright eggs. Although long disputed, evidence suggests that darker eggs do increase in temperature more rapidly than lighter eggs, explaining why dark eggs are often considered as a cost to trade-off against crypsis. Although studies have considered whether eggshell colours can confer an adaptive benefit, no study has demonstrated evidence that eggshell colours have actually adapted for this function. This would require data spanning a wide phylogenetic diversity of birds and a global spatial scale. Here we show evidence that darker and browner eggs have indeed evolved in cold climes, and that the thermoregulatory advantage for avian eggs is a stronger selective pressure in cold climates. Temperature alone predicted more than 80% of the global variation in eggshell colour and luminance. These patterns were directly related to avian nesting strategy, such that all relationships were stronger when eggs were exposed to incident solar radiation. Our data provide strong evidence that sunlight and nesting strategies are important selection pressures driving egg pigment evolution through their role in thermoregulation. Moreover, our study advances understanding of how traits have adapted to local temperatures, which is essential if we are to understand how organisms will be impacted by global climate change.

The extinction time of a general birth and death process with catastrophes

1986 ◽  
Vol 23 (04) ◽  
pp. 851-858 ◽  
Author(s):  
P. J. Brockwell
Keyword(s):  
Laplace Transform ◽  
Size Distribution ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Death Process ◽  
Extinction Time ◽  
Birth And Death Process ◽  
Different Types ◽  
The Laplace Transform ◽  
Necessary And Sufficient

The Laplace transform of the extinction time is determined for a general birth and death process with arbitrary catastrophe rate and catastrophe size distribution. It is assumed only that the birth rates satisfyλ0= 0,λj> 0 for eachj> 0, and. Necessary and sufficient conditions for certain extinction of the population are derived. The results are applied to the linear birth and death process (λj=jλ, µj=jμ) with catastrophes of several different types.

A rapid method for the direct identification of paramyxovirus in canine CSF by ultracentrifugation and negative staining as a rule out for distemper

1990 ◽  
Vol 48 (3) ◽  
pp. 594-595
Author(s):  
W.L. Steffens ◽  
M.B. Ard ◽  
C.E. Greene ◽  
A. Jaggy
Keyword(s):  
Subacute Sclerosing Panencephalitis ◽  
Clinical Signs ◽  
Viral Disease ◽  
Etiologic Agent ◽  
Mucosal Inflammation ◽  
Worldwide Distribution ◽  
Negative Stain ◽  
Viral Particles ◽  
Systemic Manifestations ◽  
Rule Out

Canine distemper is a multisystemic contagious viral disease having a worldwide distribution, a high mortality rate, and significant central neurologic system (CNS) complications. In its systemic manifestations, it is often presumptively diagnosed on the basis of clinical signs and history. Few definitive antemortem diagnostic tests exist, and most are limited to the detection of viral antigen by immunofluorescence techniques on tissues or cytologic specimens or high immunoglobulin levels in CSF (cerebrospinal fluid). Diagnosis of CNS distemper is often unreliable due to the relatively low cell count in CSF (<50 cells/μl) and the binding of blocking immunoglobulins in CSF to cell surfaces. A more reliable and definitive test might be possible utilizing direct morphologic detection of the etiologic agent. Distemper is the canine equivalent of human measles, in that both involve a closely related member of the Paramyxoviridae, both produce mucosal inflammation, and may produce CNS complications. In humans, diagnosis of measles-induced subacute sclerosing panencephalitis is through negative stain identification of whole or incomplete viral particles in patient CSF.

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