Compensatory growth and development of tail loss in Pelophylax nigromaculatus Tadpoles

2020 ◽  
Vol 40 (6) ◽  
Author(s):  
樊晓丽,林植华 FAN Xiaoli
1966 ◽  
Vol 17 (3) ◽  
pp. 375 ◽  
Author(s):  
ID Wardrop

The effect of the plane of nutrition in the first 13 weeks of post-natal life of cattle on their subsequent growth rate, body shape, and carcass composition up to 12 months of age was studied. No compensatory growth to 12 months of age was observed in calves reared to 13 weeks on low planes of nutrition. There were no significant differences between Friesian and Hereford x Friesian calves, or between males and females in empty body weight or weight gains. Treatment up to 13 weeks of age had no effect on heart girth, round, head length and width, and cannon bone length, but the remaining body measurements were reduced by low planes of nutrition during this period. Differences in carcass composition were largely a reflection of the differences in empty body weight. The carcasses of the males were heavier than those of the females and the females contained a higher proportion of fat. Carcass composition, as estimated by shin dissection, indicated that Friesian calves contained more muscle than the Hereford x Friesians, and the males more muscle than the females.


1965 ◽  
Vol 7 (2) ◽  
pp. 165-171 ◽  
Author(s):  
J. E. Duckworth

SUMMARYThe growth and carcass data were determined for pigs reared on two creep rations to different weights, and subsequently fattened with and without an antibiotic.Pigs weaned at a ‘standard’ weight of 43·8 lb. at 56 days of age grew more quickly over the range 120 to 210 lb. live-weight than pigs weighing 51·0 lb. at weaning. Both groups were fed according to a fixed scale related to live-weight. Heavy weaners growing slowly in the later stages had slightly thicker backfat measurements, indicating that they were at a more advanced stage of physiological development than the light weaners.The presence of antibiotic in the fattening ration caused no significant difference in growth rate or carcass measurements, but there were significant interactions between weaning weight and presence or absence of antibiotic in the fattening ration for length of carcass, and between sex and presence or absence of antibiotic for the traits of age at 70 lb. live-weight, carcass length and depth of mid-backfat.Weaning weight and rate of gain from 70 to 120 lb. live-weight were significantly and positively related to carcass length.It is concluded that further studies of the growth curve of the pig are required to determine the scope and importance of compensatory growth, and the interaction of growth rates in the different phases of the pig's life and their relationships to carcass traits.


Author(s):  
Randy Moore

Cell and tissue interactions are a basic aspect of eukaryotic growth and development. While cell-to-cell interactions involving recognition and incompatibility have been studied extensively in animals, there is no known antigen-antibody reaction in plants and the recognition mechanisms operating in plant grafts have been virtually neglected.An ultrastructural study of the Sedum telephoides/Solanum pennellii graft was undertaken to define possible mechanisms of plant graft incompatibility. Grafts were surgically dissected from greenhouse grown plants at various times over 1-4 weeks and prepared for EM employing variations in the standard fixation and embedding procedure. Stock and scion adhere within 6 days after grafting. Following progressive cell senescence in both Sedum and Solanum, the graft interface appears as a band of 8-11 crushed cells after 2 weeks (Fig. 1, I). Trapped between the buckled cell walls are densely staining cytoplasmic remnants and residual starch grains, an initial product of wound reactions in plants.


Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.


Author(s):  
G. M. Hutchins ◽  
J. S. Gardner

Cytokinins are plant hormones that play a large and incompletely understood role in the life-cycle of plants. The goal of this study was to determine what roles cytokinins play in the morphological development of wheat. To achieve any real success in altering the development and growth of wheat, the cytokinins must be applied directly to the apical meristem, or spike of the plant. It is in this region that the plant cells are actively undergoing mitosis. Kinetin and Zeatin were the two cytokinins chosen for this experiment. Kinetin is an artificial hormone that was originally extracted from old or heated DNA. Kinetin is easily made from the reaction of adenine and furfuryl alcohol. Zeatin is a naturally occurring hormone found in corn, wheat, and many other plants.Chinese Spring Wheat (Triticum aestivum L.) was used for this experiment. Prior to planting, the seeds were germinated in a moist environment for 72 hours.


2015 ◽  
Vol 58 ◽  
pp. 61-70 ◽  
Author(s):  
Paul B. Larsen

Ethylene is the simplest unsaturated hydrocarbon, yet it has profound effects on plant growth and development, including many agriculturally important phenomena. Analysis of the mechanisms underlying ethylene biosynthesis and signalling have resulted in the elucidation of multistep mechanisms which at first glance appear simple, but in fact represent several levels of control to tightly regulate the level of production and response. Ethylene biosynthesis represents a two-step process that is regulated at both the transcriptional and post-translational levels, thus enabling plants to control the amount of ethylene produced with regard to promotion of responses such as climacteric flower senescence and fruit ripening. Ethylene production subsequently results in activation of the ethylene response, as ethylene accumulation will trigger the ethylene signalling pathway to activate ethylene-dependent transcription for promotion of the response and for resetting the pathway. A more detailed knowledge of the mechanisms underlying biosynthesis and the ethylene response will ultimately enable new approaches to be developed for control of the initiation and progression of ethylene-dependent developmental processes, many of which are of horticultural significance.


2016 ◽  
Vol 1 (11) ◽  
pp. 81-85
Author(s):  
Melanie Hudson

The Clinical Fellowship Experience is described by the American Speech-Hearing-Language Association (ASHA) as the transition period from constant supervision to independent practitioner. It is typically the first paid professional experience for the new graduate, and may be in a setting with which the new clinician has little or even no significant practical experience. The mentor of a clinical fellow (CF) plays an important role in supporting the growth and development of this new professional in areas that extend beyond application of clinical skills and knowledge. This article discusses how the mentor may provide this support within a framework that facilitates the path to clinical independence.


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