Discontinuous gas exchange (DGE) is the main (23 individuals) breathing mode in resting adult Platynus assimilis. Few of the beetles tested (13 individuals) displayed a pattern of cyclic gas exchange or CGE. The burst of CO2 release in DGE and CGE was always accompanied by abdominal pumping (active ventilation or V). Seven individuals displayed a pattern of continuous respiration, characterized by regular abdominal pumping. Resting metabolic rate (RMR) in continuously breathing beetles was higher than in those using DGE and CGE. After treatment with sub-lethal doses of alpha-cypermethrin DGE ceased. Treated beetles were characterized by continuous pumping and almost regular periods of activity. RMR increased significantly after treatment with a pyrethroid., Irja Kivimägi ... [et al.]., and Obsahuje seznam literatury
Rhythms in abdominal pumping, heartbeats and discontinuous gas exchange cycles (DGCs) of CFV subtype (closed, flutter and ventilation periods) in adults of pine weevil Hylobius abietis were simultaneously recorded using an electrolytic microrespirometer and an infrared (IR) cardiograph or IR actograph (IRA). The cyclic release of carbon dioxide was associated with active ventilation (V phase) provided by vigorous abdominal pumping movements due to contractions of tonic longitudinal and transversal abdominal muscles, which are visible to the naked eye. On the IRA-recordings, the abdominal pumping signals are superimposed on the heartbeat spikes. The relative amplitude of the abdominal pumping signals on these recordings is more than 10 times greater than that of the heart beats. Visual observations showed that the subelytral cavity appeared to be closed during the release of carbon dioxide and open at other times. The flutter (F) of the CFV cycle is characterised by active miniature inspirations or ventilations before the V period. The miniature ventilation movements were imperceptible to the naked eye, but were recorded on the respirometer-actigraph as clear spikes. In addition, movements of the tip of the abdomen, of between 10-20 mm were seen under a stereomicroscope at a magnification of 40×. Some cycles were categorized as (C)FV cycles, when the C period disappears into the end of the V period. Abdominal pumping and miniature inspirations were clearly synchronized with the CFV cycles. Abdominal pumping movements, miniature inspirations or ventilations and heartbeats in adult H. abietis were distinguishable when recordings of the electrolytic microrespirometer-actograph and IRA were made in parallel. These three events were recognized by their different amplitudes and frequencies. It is presumed that abdominal pumping and miniature inspirations in adult H. abietis are obligatory rhythmic movements of different function and origin.
The cardiovascular system is described by parameters including blood flow, blood distribution, blood pressure, heart rate and pulse wave velocity. Dynamic changes and mutual interactions of these parameters are important for understanding the physiological mechanisms in the cardiovascular system. The main objective of this study is to introduce a new technique based on parallel continuous bioimpedance measurements on different parts of the body along with continuous blood pressure, ECG and heart sound measurement during deep and spontaneous breathing to describe interactions of cardiovascular parameters. Our analysis of 30 healthy young adults shows surprisingly strong deep-breathing linkage of blood distribution in the legs, arms, neck and thorax. We also show that pulse wave velocity is affected by deep breathing differently in the abdominal aorta and extremities. Spontaneous breathing does not induce significant changes in cardiovascular parameters., P. Langer, P. Jurák, V. Vondra, J. Halámek, M. Mešťaník, I. Tonhajzerová, I. Viščor, L. Soukup, M. Matejkova, E. Závodná, P. Leinveber., and Obsahuje bibliografii
The physiological parameters mortality, mass, oxygen consumption and amylase activity, and microanatomical features of the digestive tract, mesenchym and reproductive organs were used to characterise starvation in Galumna elimata. The mites were reared in sterilised plastic vials containing moistened zeolite at 25°C and a 12:12 photoperiod. The control group was kept under the same conditions, but pieces of bark covered with the green bark alga, Desmococcus vulgaris (syn. Protococcus viridis), were added as food for the mites. The physiological parameters were recorded after 21 days, and the microanatomical after 21 and 42 days. The guts of the starved mites were empty or filled with mucoid substances, while the guts of control mites contained food boli formed from algal cells. The mortality was significantly higher in starved animals. The mortality after 42 days of starvation was higher in males than females. The fresh mass of starved individuals significantly decreased while the water proportion content of their body tissues increased. Oxygen consumption of the starved mites was lower. Starvation did not influence the activity of amylase. Glycogeneous granulae were characteristically absent, and mucoid substances present in the guts of mites starved for 21 days. The activity of mesenteral and caecal cells, proventricular glands and cells of salivary glands was reduced after 42 days of starvation. The cells of the seminal vesicles were reduced and contained no spermatic cells in males starved for 42 days. Starved females probably resorbed immature oocytes, but had eggs in their oviducts. Starvation induces ovovivipary or larvipary in Galumna elimata.
Circellium bacchus is a flightless telecoprid (ball-rolling) dung beetle, endemic to the afrotropical region, where it is found in a few restricted populations in the eastern Cape of South Africa. Its apterous condition and large size (mass ranges from 6 to 12 g) are considered to be adaptations to a semi-arid habitat. This beetle is active in the sun for long periods, walking between widely scattered dung pats, thus is under selection pressure to reduce water loss.
C. bacchus has eight spiracles on each side of the body. The metathoracic spiracle and six abdominal spiracles open into the subelytral cavity, which is closed. The mesothoracic spiracle is the largest and most exposed, occurring ventrally in the membrane connecting the prothorax and mesothorax.
When at rest a cyclic form of respiration, known as discontinuous gas exchange cycle, is used by C. bacchus, releasing a burst of carbon dioxide approximately once an hour when the spiracles open for about 33 minutes. Flow-through respirometry was used to measure water loss from the thorax (being the head, prothorax and mesothorax) and elytral case (containing the metathorax and abdomen) separately. The total water loss of C. bacchus could be divided up as 65% cuticular water loss from the thorax, 35% cuticular water loss from the elytral case, 4% respiratory water loss from the thorax and no measurable respiratory water loss from the elytral case. 1.51 µg of water is lost for every µl of CO2 emitted during respiration in the thorax. Thus, the main avenue for both respiration and respiratory water loss is via the mesothoracic spiracles, suggesting that the primary function of the subelytral cavity is not to reduce respiratory water loss.