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2513. Activity and dormancy in relation to body water and cold tolerance in a winter-active springtail (Collembola)

Creator:
William and Zettel, Juerg
Type:
article, model:article, and TEXT
Subject:
Collembola, Hypogastruridae, winter activity, summer dormancy, body water balance, osmotically inactive water, cold hardiness, Differential Scanning Calorimetry, and thermal hysteresis
Language:
English
Description:
Ceratophysella sigillata (Collembola, Hypogastruridae) has a life cycle which may extend for >2 years in a temperate climate. It exists in two main morphs, a winter-active morph and a summer-dormant morph in central European forests. The winter-active morph often occurs in large aggregations, wandering on leaf litter and snow surfaces and climbing on tree trunks. The summer-dormant morph is found in the upper soil layers of the forest floor. The cryobiology of the two morphs, sampled from a population near Bern in Switzerland, was examined using Differential Scanning Calorimetry to elucidate the roles of body water and the cold tolerance of individual springtails. Mean (SD) live weights were 62 ± 16 and 17 ± 6 µg for winter and summer individuals, respectively. Winter-active springtails, which were two feeding instars older than summer-dormant individuals, were significantly heavier (by up to 4 times), but contained less water (48% of fresh weight [or 0.9 g g-1 dry weight]) compared with summer-dormant animals (70% of fresh weight [or 2.5 g g-1 dry weight]). Summer-dormant animals had a slightly greater supercooling capacity (mean (SD) -16 ± 6°C) compared with winter-active individuals (-12 ± 3°C), and they also contained significantly larger amounts of both total body water and osmotically inactive (unfrozen) water. In the summer morph, the unfrozen fraction was 26%, compared to 11% in the winter morph. The ratio of osmotically inactive to osmotically active (freezable) water was 1 : 1.7 (summer) and 1 : 3.3 (winter); thus unfrozen water constituted 59% of the total body water during summer compared with only 30% in winter. Small, but significant, levels of thermal hysteresis were detected in the winter-active morph (0.15°C) and in summer-dormant forms (0.05°C), which would not confer protection from freezing. However, the presence of antifreeze proteins may prevent ice crystal growth when feeding on algae with associated ice crystals during winter. It is hypothesised that in summer animals a small decrease in freezable water results in a large increase in haemolymph osmolality, thereby reducing the vapour pressure gradient between the springtail and the surrounding air. A similar decrease in freezable water in winter animals will not have such a large effect. The transfer of free water into the osmotically inactive state is a possible mechanism for increasing drought survival in the summer-dormant morph. The ecophysiological differences between the summer and winter forms of C. sigillata are discussed in relation to its population ecology and survival.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2514. Activity and exploration range of house cats in rural areas of central Poland

Creator:
Goszczyński, Jacek, Krauze, Dagny, and Gryz, Jakub
Type:
article and TEXT
Subject:
density index, transect counts, cats´ impact, and behavioural reaction
Language:
English
Description:
Domestic cats are the most numerous predators in Poland. They are commonly kept at farms but hardly controlled, so penetrate freely wide range of habitats. The work aimed at determining the range of greatest impact of cats by identifying patterns of their activity and area searching, over daily, monthly and annual cycles. The density index, estimated from transect counts, performed along standard routes, proved to be dependent on temperature, precipitation and time of the day. In spring and summer, cats presented a two-peaked activity pattern, while in cold seasons it was more stable throughout the day. In warm months cats were registered at a further distance from the buildings than in colder ones. The animals were much less active when rain was falling. Cats’ responses on noticing an observer showed that the further they were from the edges of settlements the more timid and cautious they became. The results showed that the potential pressure that cats may exert on their prey is the biggest around dawn and dusk and in summer. During a daytime it is confined to the immediate vicinity of build-up areas.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/

2515. Activity levels and predator detection by amphipods infected with an acanthocephalan parasite, Pomphorhynchus laevis

Creator:
Dezfuli, Bahram S., Maynard, Barbara J., and Wellnitz, Todd A.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Acanthocephala, Pomphorhynchus laevis, parasitized crustacean, Echinogammarus stammeri, and alteration of host activity
Language:
English
Description:
The acanthocephalan parasite Pomphorhynchus laevis (Müller, 1776) uses freshwater amphipods as its intermediate host. In order to complete the life cycle, the infected amphipod must be consumed by a fish, where the acanthocephalan will mature and reproduce. Parasite transmission, and therefore fitness, could be enhanced if infected amphipods fail to detect or avoid predatory fish. We compared the activity levels of infected and non-infected amphipods, Echinogammarus stammeri (Karaman, 1931), in both the presence and absence of odours from its natural, definitive host, the fish Leuciscus cephalus (L.). Throughout the experiment, infected amphipods were more active than were non-infected individuals. The non-infected amphipods reduced their activity after the addition of fish odours, but the infected amphipods failed to show a significant decrease. The failure of infected amphipods to reduce activity levels in the presence of fish odour may reflect a parasite strategy to increase its chances of transmission by making its amphipod host more vulnerable to predation by fish.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2516. Activity of endo-polygalacturonases in mirid bugs (Heteroptera: Miridae) and their inhibition by plant cell wall proteins (PGIPs)

Creator:
Frati, Francesca, Galletti, Roberta, de Lorenzo, Giulia, Salerno, Gianandrea, and Conti, Eric
Type:
article, model:article, and TEXT
Subject:
Miridae, Heteroptera, Curculionidae, Coleoptera, endo-polygalacturonase, PG, polygalacturonase-inhibiting proteins (PGIP), plant cell wall proteins, plant induced plant defence, direct defence, and saliva
Language:
English
Description:
Endo-polygalacturonases (PGs) are hydrolytic enzymes involved in the degradation of pectin, one of the major components of plant cell wall. While PGs from fungi, bacteria and plants have been extensively studied, PGs from insects are much less known, although they are likely to play an important role in insect-plant interactions. Presence of PGs has been reported for both piercing-sucking and chewing insect species, and possibly more commonly in mirid bugs (Heteroptera: Miridae). A screening of some common mirid species and other insects, belonging to different orders and families, was conducted using agarose diffusion assays run at different pHs. All the mirid species tested [Lygus rugulipennis Popp., L. pratensis (L.), Orthops kalmi (L.), Adelphocoris lineolatus (Goeze) and Closterotomus norwegicus (Gmelin)] showed PG activity, mainly at pH 7-8, whereas no activity was recorded for the other insect species, except Sitophilus sp. (Coleoptera: Curculionidae). PG activity in females of L. pratensis was significantly higher than in males, whereas there were no differences between the sexes in the other species. In all these species, PGs were present both in the salivary glands and the gut, with a higher activity in the salivary glands, confirming the role of these enzymes in the feeding behaviour of mirid bugs. Inhibition of mirid PGs by polygalacturonase-inhibiting proteins (PGIPs) from different plant sources was analysed at pH 7. PGIPs are extracellular plant proteins known for their ability to inhibit fungal PGs and restrict fungal colonization. Two PGIPs from Phaseolus vulgaris (PvPGIP3 and PvPGIP4) inhibited PGs of all the mirid bugs tested. This information may be helpful for the development of innovative insect-resistant plant varieties, for use in low-impact IPM.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2517. Activity of Lygus lineolaris (Heteroptera: Miridae) adults monitored around the periphery and inside a commercial vineyard

Creator:
Fleury, Diminique, Mauffette, Yves, Methot, Steve , and Vincent, Charles
Type:
article, model:article, and TEXT
Subject:
Miridae, Lygus lineolaris, tarnished plant bug, population, phenological stage of grapevine, vineyards and plant-insect relationship, and inside vs. periphery abundance
Language:
English
Description:
The tarnished plant bug, Lygus lineolaris (Heteroptera: Miridae), is a highly polyphagous pest that feeds on a broad range of economically important crops in North America. Flying L. lineolaris adults can move from crop to crop rapidly and easily. Little is known about the movement of L. lineolaris in or near vineyards. From May to October 2002 and 2003, 39 white sticky traps were positioned inside and at the periphery of a vineyard to study the movements of tarnished plant bug adults. Tarnished plant bug captures were most numerous from the end of July to mid August, with captures of ca. 3000 individuals in one week. During the vegetative season, most individuals were captured flying in and around the vineyard at a height of between 40 and 60 cm. The frequency with which the weeds were mown affected the numbers of adults captured. At the periphery of the vineyard, tarnished plant bug was more abundant near perennial vegetation, which tends to be stable (an apple orchard, a spruce wood), than in the vineyard where agronomic activities changed the availability of food. The tarnished plant bug adults did not hibernate in the vineyard. It is suggested that appropriate weed management will reduce the abundance of tarnished plant bugs in vineyards as it would deprive them of a number of suitable hosts for feeding and oviposition.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2518. Activity of paraoxonase 1 and lipid profile in healthy children

Creator:
Katarína Sumegová, Nagyová, Z., Waczulíková, I., Žitňanová, I., and Zdeňka Ďuračková
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, biochemie, lipoproteiny, ateroskleróza, biochemistry, lipoproteins, atherosclerosis, vysokodenzitní lipoprotein, lipidové peroxidy, paraoxonáza 1, HDL (high-density lipoprotein), lipid peroxides, paraoxonase 1, TEAC (trolox equivalent antioxidant capacity), 14, and 612
Language:
English
Description:
Paraoxonase 1 (PON1) seems to have a relevant role in detoxifying processes and in atherosclerosis. The aim of this study was to determine PON1 activity, the total antioxidant capacity, as well as entire lipid profile in children for screening of possible risk of atherosclerosis development. Serum PON1 arylesterase/paraoxonase activities were determined spectrophotometrically. The total antioxidant capacity of the serum was measured by TEAC method. Parameters of lipid profile were analyzed by routine laboratory methods. It has been shown that PON1 arylesterase/ paraoxonase activities were very similar to values found in adults. In children, no significant correlation between PON1 arylesterase activity and HDL was observed. PON1 paraoxonase activity correlated only with atherogenic index. PON1 arylesterase activity was significantly higher in girls than in boys. The antioxidant capacity was inversely related to the body mass index. In this study, PON1 activity was determined in healthy children aged 11 to 12 years and we found a similarity in PON1 activities of children and adults. Moreover, the results of our study support the hypothesis that higher body weight of children may contribute to a greater risk for development of atherosclerosis in which oxidative stress plays a role., K. Sumegová, Z. Nagyová, I. Waczulíková, I. Žitňanová, Z. Ďuračková., and Obsahuje bibliografii a bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2520. Activity of the laryngeal abductor and adductor muscles during cough, expiration and aspiration reflexes in cats

Creator:
Ivan Poliaček, Stránsky, A., Ján Jakuš, Helena Baráni, Zoltán Tomori, and Erika Halašová
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, kašel, kočky, cough, cats, laryngeal muscles, expiration and aspiration reflexes, electromyogram, 14, and 612
Language:
English
Description:
We studied the temporal relationships and the patterns of electromyographic activities of the posterior cricoarytenoid and thyreoarytenoid muscles (laryngeal abductor and adductor), the diaphragm and abdominal muscles in anesthetized cats during mechanically induced tracheobronchial and laryngopharyngeal coughs, expiration and aspiration reflexes. The posterior cricoarytenoid muscle activity reached the maxima just before the peak of diaphragmatic activity in both types of cough and aspiration reflexes and slightly before the top of abdominal muscle activity in coughs and the expiration reflex. Thus, this muscle contributes to the inspiratory phase of coughs and aspiration reflex and also to the expulsive phase of coughs and the expiration reflex. The thyreoarytenoid muscle presented strong discharges in the compressive phase of coughs and expiration reflex (during the rising part of the abdominal muscle activity) and in the subsequent laryngoconstriction (following the diaphragmal and/or abdominal muscle activity) in all four reflexes. This muscle was also slightly activated at the beginning of the aspiration reflex. The existence of four phases of the cough reflex is also discussed., I. Poliaček, A. Stránsky, J. Jakuš, H. Baráni, Z. Tomori, E. Halašová., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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