Sexual Reproduction in Bryophytes in Relation to Physical Factors of the Environment
R. N. Chopra, Satish C. Bhatla in Bryophyte Development: Physiology and Biochemistry, 2019
The past 25 years have witnessed considerable interest in the control of reproductive development in bryophytes by temperature, photoperiod, and other physical factors of the environment, with emphasis on the initiation of gametangia. The regular seasonal patterns of development observed in natural populations have prompted speculation concerning the influence of photoperiod and other factors on gametangial induction,24 but experimental evidence is essential before firm conclusions can be drawn. To date, the results of laboratory studies suggest that photoperiodic control of this initial stage in the reproductive process is more prevalent among hepatics and anthocerotes than in mosses.84 In the following account the term photoperiod, or day length, refers to the numbers of hours of light during a 24-h cycle, although by analogy with higher plants the length of the dark period may be a more critical factor.
Sexual Differentiation of a Neuromuscular System
Akira Matsumoto in Sexual Differentiation of the Brain, 2017
The activational effect of androgen on SNB morphology is not limited to experimental hormone manipulations: Forger and Breedlove62 showed that plasticity of SNB motoneurons can be correlated with natural fluctuations in circulating androgens. Outside their breeding season, the reproductive system of the male white-footed mouse regresses. Photoperiods are the most predictable signal of seasonal change and can be used to induce these alterations in reproductive function in the laboratory. Animals kept in short days exhibit gonadal involution and a reduction in seminal vesicle and BC/LA muscle weight in comparison with animals kept in long days. Forger and Breedlove62 found that males kept in short days also have significantly smaller SNB somata, nuclei, and dendrites than do males kept in long days. In keeping with the effect found in rats by Kurz et al.,56 SNB motoneurons in white-footed mice that were castrated and given T replacement for 4 weeks had longer dendrites (22% more) than castrates that received no T replacement. Thus, in this species, the size of SNB dendritic arbor, somata, and nuclei is under androgenic control and is contingent upon naturally fluctuating T levels.
Eating Disorders and Treatment
Emily Crews Splane, Neil E. Rowland, Anaya Mitra in Psychology of Eating, 2019
This model is not only task-related but, because birds are seasonal breeders, will be associated with specific day length (photoperiod) indicative of the season. If animals show physiological and behavioral changes in different seasons, they are said to be photoperiodic. There are other photoperiod-related changes in food intake. Many species eat less in the winter when days are short and lose substantial body weight (e.g., 20%; Iverson & Turner, 1974), and, like the incubating birds, this occurs even in captivity when food is readily available. In the natural environment, food tends to be less abundant during the winter, and expending large amounts of energy in unsuccessful foraging is a poor survival strategy. The physiological suppression of hunger then has an adaptive function. Another example is in rutting deer (Yoccoz et al., 2002): The males lose 10% to 15% of their body weight during rutting season, even though there is plenty of grass around; in contrast, females do not lose weight.
Melatonin-stimulated biosynthesis of anti-microbial ZnONPs by enhancing bio-reductive prospective in callus cultures of Catharanthus roseus var. Alba
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Hafiza Rida Riaz, Syed Salman Hashmi, Tariq Khan, Christophe Hano, Nathalie Giglioli-Guivarc’h, Bilal Haider Abbasi
Melatonin (N-acetyl-5-tryptamine) is a PGR and belongs to the family indole-amines [24,25]. It governs the growth of explants, shoots and roots. It helps in activation of rhizogenesis and delays leaf senescence [26]. Melatonin, having the natural antioxidant capacity, plays an important role during abiotic stress such as heat, salinity, cold, drought, UV-radiation, herbicides and chemical pollutants [27,28]. Melatonin proved to be efficient in inducing defence either local or systematic against photo-oxidative stress [29]. It plays important role in photoperiodism such as flowering [30]. Melatonin has been reported for enhanced Ag-NPs synthesis by improving bio-reductive potential [19]. In the present work, melatonin is investigated for enhanced ZnONPs synthesis and anti-bacterial efficacy by improving phytochemical constituents when applied exogenously in callus cultures of C. roseus. Further, melatonin is compared with other PGRs (NAA, Kin, TDZ and 2,4-D) for its potential to improve the phytochemical status of C. roseus callus cultures.
Hypothalamus but not liver retains daily expression of clock genes during hibernation in terai tree frog (Polypedates teraiensis)
Published in Chronobiology International, 2020
Bijoy Krishna Borah, Zothanmawii Renthlei, Amit Kumar Trivedi
Vertebrate organisms adjust the period of endogenous clock(s) to correspond to annual photoperiod changes to perform seasonal physiological processes like hibernation, migration, and reproduction (Helm et al. 2013; Kumar et al. 2010). These seasonal breeders differ in their physiology during different seasons of the year and is called annual life history states (Trivedi et al. 2014). To respond to the environmental photoperiod cycle, organisms require behavioral and physiological plasticity (Stevenson and Ball 2011). To cope with adverse environmental conditions, organisms have evolved different strategies. Invertebrate organisms (insects) undergo dormancy called diapause (Bradshaw and Lounibos 1977), while some higher animals either migrate (Kumar et al. 2010) or hibernate/aestivate (Williams et al. 2017) during unfavorable environmental conditions. Hibernation is an energy conservation strategy to cope with adverse environmental conditions (Carey et al. 2003; Roots 2006). During hibernation, metabolic rate, heart rate, and oxygen consumption can all be reduced (Storey and Storey 2004). Hibernation physiology has been extensively investigated in mammals (Fedorov et al. 2009; Geiser 2004; Lei et al. 2014; Ruf and Geiser 2015; Storey and Storey 2004; Yan et al. 2006), with emphasis mostly on metabolic genes, which are differentially expressed during hibernation (Srere et al. 1992; Williams et al. 2005).
Differential expression of flowering genes in Arabidopsis thaliana under chronic and acute ionizing radiation
Published in International Journal of Radiation Biology, 2019
Maryna V. Kryvokhyzha, Konstantin V. Krutovsky, Namik M. Rashydov
Early flowering of A. thaliana in response to drought stress, UV-C, and pathogens (for example, Fusarium oxysporum infection) was demonstrated recently (Takeno 2016). We observed that the low dose of 3 cGy irradiation exposure also promotes early flowering in A. thaliana plants. Published studies have also shown that the FT gene could be involved in stress-induced flowering (Takeno 2012). However, we did not observe its increased expression in earlier flowering (King et al. 2008). The photoperiodic CO gene was upregulated and followed by flowering acceleration. Our study has shown that the effects of the 17 cGy chronic and 15 Gy acute irradiations were similar to the UV-B effect (Ali et al. 2015). The short-wavelength UV light can cause photolesions and cyclobutane–pyrimidine dimers in DNA and its structural disintegration (Brem et al. 2017; Chen et al. 2017).
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