Correlation of seasonal acclimatization in metabolic enzyme activity with preferred body temperature in the Eastern red spotted newt (Notophthalmus viridescens viridescens)

Eastern red spotted newts, as aquatic adults, are active year round. They are small and easy to handle, and thus lent themselves to a laboratory study of seasonal changes in preferred body temperature and biochemical acclimatization. We collected newts in summer (n=20), late fall (n=10) and winter (n=5). Ten each of the summer and late fall newts were subjected to an aquatic thermal gradient. Summer newts maintained higher cloacal temperatures than late fall newts (26.8+/-0.5 degrees C and 17.2+/-0.4 degrees C, respectively). In addition, the activity of three muscle metabolic enzymes (cytochrome c oxidase (CCO), citrate synthase (CS) and lactate dehydrogenase (LDH)) was studied in all newts collected. Newts compensated for lower late fall and winter temperatures by increasing the activity of CCO during those seasons over that in summer newts at all assay temperatures (8, 16 and 26 degrees C). The activity of CS was greater in winter over summer newts at 8 and 16 degrees C. No seasonal differences in LDH activity were demonstrated. These data in newts indicate that this amphibian modifies some muscle metabolic enzymes in relation to seasonal changes and can modify its behavioral in a way that correlates with those biochemical changes.     

Exposure to solar radiation drives organismal vulnerability to climate: Evidence from an intertidal limpet

Understanding the physiological abilities of organisms to cope with heat stress is critical for predictions of species’ distributions in response to climate change. We investigated physiological responses (respiration and heart beat rate) of the ectotherm limpet Patella vulgata to heat stress events during emersion and the role of seasonal and microclimatic acclimatization for individual thermal tolerance limits. Individuals were collected from 5 microhabitats characterized by different exposure to solar radiation in the high intertidal zone of a semi-exposed rocky shore in winter and summer of 2014. Upper thermal tolerance limits (heat coma temperatures – HCTs, and heart rate Arrhenius break temperatures - ABTs) were determined for individuals from each microhabitat in both seasons under laboratory conditions. While we found a clear seasonal acclimatization, i.e., higher HCTs and ABTs in summer than in winter, we did not find evidence for microhabitat-specific responses that would suggest microclimatic acclimatization. However, operative limpet temperatures derived from in-situ temperature measurements suggest that individuals from sun exposed microhabitats have a much narrower thermal safety margins than those from less exposed surfaces or within crevices. Microhabitat specific thermal safety margins caused by high thermal heterogeneity at small spatial scales and the lack of short term acclimatization will likely shape small scale distribution patterns of intertidal species in response to the predicted increase in the frequency and intensity of heat waves.     

Micropropagation of strawberry tree (<Emphasis Type="Italic">Arbutus unedo</Emphasis> L.) from adult plants

Arbutus unedo L. is a species of strawberry tree, widely represented in the Mediterranean climates of southern Europe. Fruits are used to make jellies and a spirit called “medronheira.” Shoot apices and nodal segments from epicormic and coppiced shoots of adult plants were used for plant propagation. Shoot apices from epicormic shoots, which were developed in a growth chamber, showed higher rates of in vitro establishment. The results also indicated that shoot apices are more effective for plant establishment than nodal segments, with rates of establishment significantly higher after 12 wk of culture. Of the three basal media used in combination with 9.0 μM benzyladenine and 0.087 M sucrose, the FS medium with the micronutrients of the Murashige and Skoog medium gave the highest rates of multiplication, especially when the parameter analyzed was the number of clusters formed. When shoot apices from selected adult plants (AL01–AL06) were tested, the multiplication rate was not significantly different among the plants. However, in the conditions tested, shoots from the clones AL1, AL2, and AL3 showed better development, whereas shoots from AL4, AL5, and AL6 showed an impaired development and could not be rooted. Rooting was achieved in all the conditions tested, even in the absence of auxin. The inclusion of an auxin significantly increased root formation, whereas the addition of charcoal did not improve root formation. Rooted plantlets were acclimatized, and some of them are now in the field for further study.     

Zeatin-induced one-step in vitro cloning affects the vegetative growth of cranberry (<Emphasis Type="Italic">Vaccinium macrocarpon</Emphasis> Ait.) micropropagules over stem cuttings

Shoot proliferation and rooting of three cranberry (Vaccinium macrocarpon Ait.) cultivars Bergman, Pilgrim, and Stevens were obtained in vitro on a modified nutrient medium containing zeatin following a one-step procedure. Bergman and Stevens differed in terms of shoot height, leaf number per shoot, rooting frequency, root number per explant, and root length; this was manifested with various concentrations of zeatin. Shoots proliferated and roots developed best when nodal segments were cultured in the medium supplemented with very low concentration of zeatin (2–4 μM). Such zeatin-induced tissue culture (TC) shoots of Bergman, Pilgrim, and Stevens were rooted ex vitro and compared with those propagated by conventional softwood cuttings (SC) for growth and morphology over four growth seasons. Significant interactions for leaf number per upright were observed among the treatments. The cultivars differed in terms of runner number per plant, upright length, number of leaves per upright, and shoot vigor. The propagation method had an effect on morphology of cranberry plants. The TC plants produced more runners and uprights with more leaves per upright than the conventional cuttings. This increase in vegetative growth of in vitro-derived plants over stem cuttings varied among genotypes. In vitro culture on zeatin-containing nutrient medium apparently induces the juvenile branching characteristics that favored enhanced vegetative growth with more shoots and leaf production.     

Non-Zygotic Embryogenesis in Hardwood Species

Hardwood species are valuable biological resources that have an important role in the economy and ecology of ecosystems worldwide. Non-zygotic or somatic embryogenesis (SE) is a powerful tool in plant biotechnology as it is a form of clonal propagation, amenable to cryopreservation of valuable germplasm and genetic transformation including gene editing. The SE process involves five steps and includes somatic embryo induction, proliferation, maturation, plantlet conversion, and subsequent plant acclimatization. This review aims to provide a general overview of these steps in different SE systems developed for hardwood species. Factors that influence the induction stage such as the age of the donor plant, genotype and culture media are discussed. The role of different explant types, i.e. zygotic embryos and non-zygotic tissues, such as roots, flower tissues, nodes, internodes, leaves or shoot apices, in SE induction are especially emphasized. Histological studies of the origin of somatic embryos and the sequence of events leading to their development from initial explants are assessed. Maintenance of embryogenic capacity carried out by subculture of embryogenic inocula on semisolid or liquid media through cell suspension cultures or by temporary immersion systems is described. At present, the main concerns associated with the application of SE for large-scale propagation of elite hardwoods are related to the embryo maturation, germination, and plantlet conversion steps, and these are highlighted in this review. Finally, molecular aspects associated with somatic embryo induction and development are also described. Attempts to overcome the hurdles identified in the embryogenic process, and future lines of research are proposed.     

鱼类适应环境温度的代谢补偿及其线粒体水平的调节机制

由于水体环境所处的纬度及水体的深度、盐度、流动状态的不同,其温度状态在地球上的空间分布格局千变万化,水生生动物在进化过程中形成了一系列适应不同环境温度的生理生态学机制,尤其是进化出可生存于极端温度条件下的多个物种,扩大了动物的分布范围,     

GENETIC,ACCLIMATIZATION, AND ONTOGENETIC EFFECTS ON HABITAT SELECTION BEHAVIOR IN DAPHNIA PULICARIA

Daphnia pulicaria from three different populations were observed to express within-population variation in habitat-choice behavior in field assays. Individuals from different habitats (i.e., lake depths) were isolated and cultured as clonal lines under standard conditions. Habitat choices by clonal descendants were then estimated in the field, using replicate experimental columns. There was significant heritable and ontogenetic variation in habitat choice, but the heritable effect was small relative to the phenotypic variation of the original isolates. In a second set of experiments, D. pulicaria that were acclimatized to different habitats showed a strong tendency to choose the habitat to which they had been acclimatized. These data suggest that a given genotype can use a wide range of habitats, given appropriate acclimatization. Although genetic variation is significant, we hypothesize that natural selection on correlated ecological traits is more likely to maintain patterns of genotypic segregation among habitats in Daphnia.     

Photosynthetic competence of plantlets grown in vitro. An automated system for measurement of photosynthesis in vitro

An aseptic gas exchange and hydroponic system (AGEHS) has been developed in an attempt for characterization of physiological requirements for photoautotrophic growth in vitro and alleviation of the needs for ex vitro acclimatization. The AGEHS monitors and controls several parameters relevant to plant growth. Shootlets of Chrysanthemum × morifolium Ramat. cv. Envy were treated with flow of air or CO₂-enriched air under controlled relative humidity, elevated photosynthetic photon flux density (PPFD) and hydroponic irrigation. After 15 days of treatment, plantlets gained more than 3 times as much dry weight as those from a conventional culture tube treatment. This study shows that it is possible to favour photoautotrophic growth when elevated PPFD, enhanced air-exchange and hydroponic medium flow are provided concurrently. This enhancement is achievable through careful increments of light quanta, balanced with increments of humidified air flow and/or CO₂ content in air which seem to be necessary to avoid potential photoinhibition and premature water exhaustion from gelled media.     

Genetic,acclimatizational and anthropometric factors in hand cooling among North and South Chinese

The left hands of unacclimatized North Chinese (N = 16) and South Chinese (N = 13) were exposed to 5°C water for 30 minutes followed by a 10 minute recovery period. Significant differences independent of body composition were found between the two samples on mean 30 minute temperature during immersion, time and temperature of the onset of initial CIVD (cold-induced vasodilation) at 0.01, 0.05 and 0.10 levels respectively. The result suggests the presence of a genetic component in the cold responses of Continental Asian populations and the possibility of the presence of a clinal distribution of cold response in Asia.     

Influence of mycorrhization on physiological parameters of micropropagated Castanea sativa Mill. plants

 Mycorrhizal micropropagated Castanea sativa plants were studied in terms of growth and physiological parameters following in vitro mycorrhization with Pisolithus tinctorius. Mycorrhization enhanced growth of micropropagated chestnut plants, increased their protein content and photosynthetic rates, decreased the respiratory rates and CO₂ compensation point. RuBisCO activity was not significantly different in mycorrhizal and control plants, although there was an increase in the amount of RuBisCO in the former. Mycorrhization increased plant biomass and improved plants physiological status, thus enhancing the acclimatization process. Accepted: 21 May 1997