scholarly journals Regeneration niche of the Canarian juniper: the role of adults, shrubs and environmental conditions

2010 ◽  
Vol 67 (7) ◽  
pp. 709-709 ◽  
Author(s):  
Rüdiger Otto ◽  
Bertil O. Krüsi ◽  
Juan D. Delgado ◽  
José María Fernández-Palacios ◽  
Eduardo García-Del-Rey ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Regeneration Niche

scholarly journals Fisiología y ecología del fitocromo: su función en las semillas

2017 ◽  
pp. 71
Author(s):  
Alma Orozco-Segovia
Keyword(s):  
Environmental Conditions ◽  
Rain Forest ◽  
Los Tuxtlas ◽  
Developmental Processes ◽  
Plant Pigment ◽  
The Subject ◽  
Forest Plants

Phytochrome is the plant pigment which participate in several developmental processes regulated by light. In recent years this pigment has been associated with the detection of the environmental conditions but there is still a gap of information concerning the physioecological role of the pigment. In this paper the knowledge of the role of phytochrome on seed photoblastism is analysed based on several recent works done on the subject mainly with pioneer rain forest plants from Los Tuxtlas, Veracruz.

Sensitivity cycling and its ecological role in seeds with physical dormancy

2009 ◽  
Vol 19 (1) ◽  
pp. 3-13 ◽  
Author(s):  
K.M.G. Gehan Jayasuriya ◽  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Life Cycle ◽  
Environmental Conditions ◽  
Common Phenomenon ◽  
Ecological Role ◽  
Dormancy Breaking ◽  
Physical Dormancy ◽  
Physiological Dormancy ◽  
Seed Coats

AbstractCycling of physically dormant (PY) seeds between states insensitive and sensitive to dormancy-breaking factors in the environment has recently been demonstrated inFabaceaeandConvolvulaceae, and it may be a common phenomenon in seeds with water-impermeable seed coats. In contrast to seeds of many species with physiological dormancy (PD), those with PY cannot cycle between dormancy and non-dormancy (ND). In this paper, we evaluate the role of sensitivity cycling in controlling the timing of germination of seeds with PY in nature, and show that sensitivity cycling in seeds with PY serves the same ecological role as dormancy cycling in seeds with PD. Thus, sensitivity cycling in seeds with PY ensures that germination in nature occurs only at (a) time(s) of the year when environmental conditions for growth are, and are likely to remain, suitable long enough for the plant to complete its life cycle or to form a perennating structure. Further, we describe the experimental procedures necessary to determine whether sensitivity cycling is occurring, and discuss briefly the possible relevance of sensitivity cycling to dormancy classification.

Spatial and seasonal variation in dissolved silica benthic fluxes in the shallow zones of the southern Baltic Sea

2021 ◽  
Author(s):  
Zuzanna Borawska ◽  
Beata Szymczycha ◽  
Marc J. Silberberger ◽  
Marta Szczepanek ◽  
Katarzyna Koziorowska-Makuch ◽  
...  
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Environmental Conditions ◽  
Benthic Fauna ◽  
Benthic Fluxes ◽  
Dissolved Silica ◽  
Szczecin Lagoon ◽  
Southern Baltic Sea ◽  
Puck Bay

<p>Dissolved silica (DSi) is an important macronutrient in the marine environment, necessary for growth of many aquatic organisms. Yet, DSi marine cycle is still not fully recognized, especially in dynamic, coastal zones. Although DSi is mainly transported to the sea by rivers, benthic fluxes of DSi, which originate from dissolution of the siliceous remains in the sediments, can also represent an important source of bioavailable silicon in the ocean. Benthic DSi fluxes are mainly powered by diffusion, but their rates are strongly shaped by the benthic fauna. Still, the role of benthos in these processes is not fully recognized. The main goal of this study was to investigate how various environmental factors and benthic fauna may shape the coastal cycle of Si in coastal environments during different seasons.</p><p>Our study was conducted in the shallow coastal ecosystems of the southern Baltic Sea characterized by contrasting environmental conditions: shallow, brackish and enclosed Szczecin Lagoon (Oder river estuary), dynamic open waters near Łeba with relatively low anthropogenic influence, enclosed Puck Bay and Vistula prodelta. We investigated both shore ecosystems (app. 0.5 m depth) and deeper areas (from 6 up to 60 m depth). DSi concentrations in the bottom waters and environmental characteristics (T, S, O<sub>2</sub>, sediment organic matter) were investigated at 6 stations, during three seasons (winter, spring and autumn) in years 2019-2020 with s/y Oceania (IOPAN) and directly from the shore. Additionally, samples from shore stations were collected during summer. DSi benthic fluxes were determined at each station by performing <em>ex situ</em> incubations of sediment cores (n = 4-5) with natural benthic assemblages. The benthic organisms in studied cores were collected, identified, counted, and weighed.</p><p>The lowest fluxes were measured at sandy stations while highest return fluxes were observed at muddy sites. High variability in DSi benthic fluxes along studied localities was observed, ranging from -1.11 mmol d<sup>-1</sup>m<sup>-2</sup> in summer at shore station in the Puck Bay and up to 6.79 mmol d<sup>-1</sup>m<sup>-2</sup> in Szczecin Lagoon in autumn. We used  Gaussian Generalized Linear Models (GLMs) to estimate the role of environmental conditions, benthic fauna characteristics  and interactions among them in the variability of DSi benthic flux across studied localities. The most important predictors for the fluxes were all pair-wise interactions of temperature, total organic carbon, the C/N molar ratio, and the density of benthic macrofauna. Both interaction terms that included C/N ratio, a measure of organic matter quality (i.e. low C/N ratio indicates higher quality), were associated with increased DSi uptake by the sediment. Further, the interaction term between T and benthic marcofauna density was also linked to negative benthic fluxes of DSi. In contrast, the interaction of T and TOC caused a strong increase in DSi return fluxes.</p>

Towards understanding the neural origins of hibernation

2022 ◽  
Vol 225 (1) ◽  
Author(s):  
Madeleine S. Junkins ◽  
Sviatoslav N. Bagriantsev ◽  
Elena O. Gracheva
Keyword(s):  
Nervous System ◽  
Environmental Conditions ◽  
Calcium Imaging ◽  
Essential Role ◽  
Physiological Responses ◽  
Quiescent State ◽  
Physiological Changes ◽  
In Vivo Calcium Imaging

ABSTRACT Hibernators thrive under harsh environmental conditions instead of initiating canonical behavioral and physiological responses to promote survival. Although the physiological changes that occur during hibernation have been comprehensively researched, the role of the nervous system in this process remains relatively underexplored. In this Review, we adopt the perspective that the nervous system plays an active, essential role in facilitating and supporting hibernation. Accumulating evidence strongly suggests that the hypothalamus enters a quiescent state in which powerful drives to thermoregulate, eat and drink are suppressed. Similarly, cardiovascular and pulmonary reflexes originating in the brainstem are altered to permit the profoundly slow heart and breathing rates observed during torpor. The mechanisms underlying these changes to the hypothalamus and brainstem are not currently known, but several neuromodulatory systems have been implicated in the induction and maintenance of hibernation. The intersection of these findings with modern neuroscience approaches, such as optogenetics and in vivo calcium imaging, has opened several exciting avenues for hibernation research.

EFFECT OF AIR VELOCITY ON INHALATION DOSES DUE TO RADON AND THORON PROGENY IN A TEST CHAMBER

2020 ◽  
Vol 189 (3) ◽  
pp. 401-405
Author(s):  
Rosaline Mishra ◽  
Rama Prajith ◽  
Rajeswari Pradhan Rout ◽  
Jalaluddin Sriamirullah ◽  
Balwinder Kaur Sapra
Keyword(s):  
Physical Properties ◽  
Environmental Conditions ◽  
Test Chamber ◽  
Air Velocity ◽  
Attachment Rate ◽  
Inhalation Dose ◽  
Decay Products ◽  
Calibration Chamber ◽  
Thoron Progeny

Abstract Inhalation doses due to radon and thoron are predominantly due to the inhalation of progeny of Radon and Thoron. The progeny/decay-products of radon and thoron are particulates unlike their parent gas and exhibit different physical properties like attachment to the aerosols and deposition on different surfaces. All these properties in turn depend on the environmental conditions such as air velocity, aerosol concentration, attachment rate, etc. The role of air velocity on deposition on surfaces decides the progeny particles left in the air for inhalation. Therefore, in the present work, we have studied the effect of air velocity on the inhalation dose due to radon and thoron progeny at the centre of a 0.5-m3 calibration chamber as well as on all surfaces. Hence, the studies were carried out at different air velocities, and inhalation doses were measured using deposition-based direct radon and thoron progeny sensors.

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