Aging versus Growth

Rj, Goss

doi:10.1353/pbm.1974.0051

Cited by 26 publications

(9 citation statements)

References 20 publications

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“…A similar idea is still prevalent in certain recent litera ture [9,10]. But this concept has been clearly disproven by studies on wild fish populations together with experimental findings in the laboratory.…”

Section: Evidences For Ageing In Fishmentioning

confidence: 93%

Ageing in Fishes

1994

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Fishes show three types of senescence. Lampreys, eels and pacific salmon exhibit rapid senescence and sudden death at first spawning. The guppy, red panchax, medaka, platyfish, Indian murrel and many other teleosts undergo gradual senescence, as observed in most of the vertebrates. A number of fishes (e.g. sturgeons, paddlefish, female plaice, flatfish, rock-fish) show indeterminate growth, the occurrence of senescence in them is supposed to be very slow or negligible. Neuroendo-crine mechanisms are involved in rapid senescence. Most of the evidences in favour of the occurrence of senescence in fishes have been derived from studies in species showing gradual senescence. Age-related increases in mortality rate, accumulation of lipofuscin, lipid peroxidation, collagen cross-linking and decreases in growth rate, reproductive capacity and protein utilisation are clearly marked in such species. Anatomical changes in various organs during ageing also confirm increases in degenerative changes and pathological symptoms. Dietary restriction and lower environmental temperature retard the ageing processes in a few species showing gradual senescence. These results tentatively support the contention of commonality in mechanism of ageing processes in vertebrates. At present, anatomical, cellular, biochemical and genetic evidences in support or against the occurrence of slow senescence or negligible senescence in long-lived fish species are almost nonexistent. Extensive studies on ageing in fishes are needed to explain the multiple mechanisms which are not unexpected considering the number and variety of the existing species.

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Section: Evidences For Ageing In Fishmentioning

confidence: 93%

Ageing in Fishes

1994

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“…Treated fish were 6% longer (P < 0.05) than controls at the end of the experiment (Table 2), but their rate of length gain in relation to whole body weight gain was 12% lower (Figure 2). Gonadal steroids are known to curtail linear growth in mammals by promoting early closure of the cartilaginous growth plate of bone (Hall 1978), but fish do not possess a growth plate (Goss 1974). Bone tissue simply may not be as sensitive to the anabolic effects of MT as other tissues in rainbow trout.…”

Section: Resultsmentioning

confidence: 99%

Influences of Anabolic Hormone Treatment and Dietary Protein: Energy Ratio on Condition and Muscle Deposition of Rainbow Trout

Ostrowski¹,

Garling²

1988

The Progressive Fish-Culturist

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The effects of dietary 17a-methyltestosterone (MT) and protein-to-metabolizable energy (P:M£) ratios on the weight gain of individual body components and their relative contribution to the condition factor (K) were examined for juvenile rainbow trout (Salmo gairdneri). Five semipurified isocaloric diets (390 kcal/100 g dry ingredients) containing 80, 100, 120, 140, and 160 mg protein/kcal ME were prepared with and without 2.0 mg MT/kg of diet and fed to 5-g rainbow trout for 8 weeks. At the end of the experiment, fish were weighed and measured, and then dissected or cooked to obtain individual wet weights of the head, fins, skin, muscle, carcass bone, viscera, and rib section. Steroid treatment increased the weight gain of muscle tissue in direct proportion to the increase in body weight gain. Linear bone growth was enhanced with treatment, but the rate of increase did not keep pace with the rate of weight increase of the rest of the body. This accounted for a lowered percentage bone weight gain and increased K (100-[fish weight, g]/[total length, cm] 3 ) of MT-treated fish. Dietary P:ME ratio had little effect on K of the fish.

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“…There is a decrease in functional units in tissues with age, e.g., the number of alveoli in human lungs may decrease from 300 ϫ 10 6 in young adults to 60 ϫ 10 6 in old age, and the number of nephrons in kidneys decreases from 2 ϫ 10 6 to 1 ϫ 10 6 in the same period (31). This decrease would allow for compensatory hyperplasia in the remaining functional units.…”

Section: Discussionmentioning

confidence: 99%

Coculturing diverse clonal populations prevents the early-stage neoplastic progression that occurs in the separate clones

Chow¹,

Rubin²

2000

Proc. Natl. Acad. Sci. U.S.A.

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Most human cancers are of monoclonal origin and display many genetic alterations. In an effort to determine whether clonal expansion itself could account for the large number of genetic alterations, we compared spontaneous transformation in cloned and uncloned populations of NIH 3T3 cells. We have reported that progressive transformation of these cells, which is driven by the stress of prolonged contact inhibition at confluence, occurs far more frequently in cultures of recent monoclonal origin than in their uncloned progenitors. In the present work we asked how coculturing six clones at early and late stages of progression would affect the dynamics of transformation in repeated rounds of confluence. When coculture started with clones in early stages of transformation, marked by light focus formation, there was a strong inhibition of the progression to the dense focus formation that occurred in separate cultures of the individual clones. In contrast, when coculture started after the individual clones had progressed to dense focus formation, there was selection of transformants from the clone producing the largest and densest foci. Mixing the cells of a single clone with a large excess of uncloned cells from a subline that was refractory to transformation markedly decreased the size of dense foci from clones in transit from light to dense focus formation, but had much less effect on foci from clones with an established capacity for dense focus formation. The major finding of protection against progression by coculturing clones in early stages of transformation suggests that the expansion of a rogue clone in vivo increasingly isolates many of its cells from genetically stabilizing interactions with surrounding clones. Such clonal isolation might account for the increase in mutation rates associated with the dysplasia in colorectal adenomas that signifies the transition between benign and malignant growth.progressive transformation ͉ clonal susceptibility ͉ polyclonal resistance ͉ critical mass ͉ age-dependence of cancer I t generally is accepted that most human cancers are clonal in origin (1-3). Extremely large numbers of genetic changes have been found in these growths. For example, more than 25% of the heterozygous loci in sporadic cases of colorectal cancer exhibit loss of heterozygosity (LOH) (4). More than half of the cases of esophageal adenocarcinoma reveal extensive LOH of polymorphic microsatellite markers along the entire length of a single chromosome (5). A large increase in the frequency of mutations is found in the highly dysplastic lesions that mark the transition in colorectal adenomas to carcinomas (6). This finding suggests that the lesions have to reach a certain minimal size and degree of disorganization to drive the many genetic changes that underlie progression to malignancy. It had been proposed earlier that a critical mass of cells bearing the same or similar mutations was needed to produce the malignant state (7). Quantitation of the critical mass concept closely fit the age-related increa...

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Aging versus Growth

Cited by 26 publications

References 20 publications

Ageing in Fishes

Ageing in Fishes

Influences of Anabolic Hormone Treatment and Dietary Protein: Energy Ratio on Condition and Muscle Deposition of Rainbow Trout

Coculturing diverse clonal populations prevents the early-stage neoplastic progression that occurs in the separate clones

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