45 research outputs found
The effect of different photoperiods on growth and smoltification in Atlantic salmon (Salmo salar)
Photoperiod has been implicated as an effective mediator of
growth and smelting in Atlantic salmon (Salmo salar). To investigate
this 0+ parr of Atlantic salmon were treated with three
different photoperiods: 24Light:0Dark; 16L:8D; 8L:16D; held static
during the experimental period.
This preliminary report shows that growth was greatest under
the continous light regime, followed by the 8L:16D photoperiod
and the 8L:l6D regime.
Several bloodparametres were measured as indicators of stress.
These indicators showed no large differences between photoperiods.
Thus, extended periods of light does not seem to stress
the fish, on the contrary, manipulating photoperiods is an
effective means of increasing growth and controlling smelting in
Atlantic salmon
The effect of different photoperiods on growth and smoltification in Atlantic salmon (Salmo salar)
Photoperiod has been implicated as an effective mediator of
growth and smelting in Atlantic salmon (Salmo salar). To investigate
this 0+ parr of Atlantic salmon were treated with three
different photoperiods: 24Light:0Dark; 16L:8D; 8L:16D; held static
during the experimental period.
This preliminary report shows that growth was greatest under
the continous light regime, followed by the 8L:16D photoperiod
and the 8L:l6D regime.
Several bloodparametres were measured as indicators of stress.
These indicators showed no large differences between photoperiods.
Thus, extended periods of light does not seem to stress
the fish, on the contrary, manipulating photoperiods is an
effective means of increasing growth and controlling smelting in
Atlantic salmon
ANALISIS KEMAMPUAN BERFIKIR ALJABAR DI KELAS VII SMP NEGERI 1 KRANGKENG KABUPATEN INDRAMAYU (Studi Survei di Kelas VII Tahun Akademik 2012/2013)
Setiati Rahayu, 2013. Analisis Kemampuan Berfikir Aljabar di Kelas VII di SMP
Negeri 1 Krangkeng Kab. Indramayu (Studi Survei di Kelas VII Tahun
Akademik 2012/2013)
Untuk mengukur kemampuan berfikir aljabar seorang siswa diperlukan
beberapa indikator. Terdapat beberapa indikator untuk memahami aljabar
diantaranya memahami pengertian koefisien variabel suku sejenis, kemampuan
melakuakan operasi hitung, kemampuan mengggunakan simbol matematika,
kemampuan menggunakan bahasa sehari-hari, kemampuan menyederhanakan
operasi aljabar, kemampuan menyatakan berbagai hubungan, kemampuan
menggunakan diagram alur dan memahami konsep aljabar invers.
Tujuan dalam penelitian ini untuk menganalisis kemampuan berfikir
aljabar di kelas VII yang ditinjau dari operasi aljabar, penggunaan aljabar,
masalah aljabar, dan pemahaman konsep aljabar saat menjawab soal-soal aljabar.
Kemampuan siswa dalam memahami aljabar merupakan suatu kondisi yang
terdapat dalam sekolah SMP tersebut.
Aljabar adalah suatu cabang ilmu matematika yang menggunakan tandatanda
dan huruf-huruf yang mewakili angka-angka. Banyaknya indikator yang
menjadi indikator kemampuan aljabar, maka akan ada beberapa indikator yang
akan menjadi komponen utama dalam kemampuan aljabar. Untuk mengetahui
kemampuan siswa dalam memahami aljabar, tidak perlu semua indikator pada\ud
materi aljabar diujikan dalam tes. Mengetahui sangat pentingnya komponen utama
dalam materi aljabar untuk mengukur kemampuan berfikir aljabar seorang siswa
maka peneliti mencoba menganalisis kemampuan berfikir aljabar siswa kelas VII
di SMPN 1 Krangkeng.
Teknik pengumpulan data yang digunakan dalam penelitian ini adalah tes.
Populasi dalam penelitian ini adalah Kelas VII yang berjumlah (160 siswa).
Sampel diambil dari kelas VIIB cluster random sampling. Untuk uji coba
dilakukan di kelas VIIA yang berjumlah 32.
Dari hasil penelitian diperoleh hasil sebagai berikut: 1) Aljabar di SMP N
1 Krangkeng cukup baik hal ini ditunjukan dengan nilai rata-rata 75. 2) Indikator
kemampuan berfikir aljabar secara mekanisme dan indikator Kemampuan terbesar
yang dicapai oleh siswa kelas VII SMP Negeri 1 Krangkeng tahun ajaran
2012/2013 dalam memahami aljabar adalah pada pengertian koefisien, variabel,
konstanta, faktor, suku sejenis adalah sebesar 89.58% dan kemampuan yang
kurang dikuasai oleh siswa kelas VII SMP Negeri 1 Krangkeng tahun ajaran
2012/2013 dalam memahami aljabar adalah memahami invers adalah sebesar
85.94%. 3) Dari delapan indicator kemampuan berfikir aljabar ada tiga komponen
yang dominan yaitu menggunakan diagram alur, pengertian koefisien variable
konstanta, faktor suku sejenis, dan menyederhanakan operasi aljaba
Seawater adaptability of two strains of arctic char (Salvelinus alpinus) reared under different light regimes
Groups of Arctic char (Salvelinus alpinus) were reared under
three experimental light regimes. Two different strains of char
were used, one non-migratory from south Norway, the other anadromous
from northern Norway. All groups received a continous
background illumination. One of the experimental light regimes
consisted only of this background illumination. The remaining
two treatments consisted of an additional simulated natural photoperiod,
using either yellow light or daylight. Growth rate was
monitored during the experiment. A Seawater Challenge Test
(SWCT) was run for 24 hours to evaluate the ability of the two
strains of char to tolerate and survive in seawater.
There were no significant differences in growth rate in either
strain between the experimental light regimes. Condition factor
increased during the experimental period for fish of both
strains and all light regimes. Both strains tolerated the SWCT
without mortalities. Size seems to be the most important factor
for seawater adaptability of Arctic char. There were no signs of
a smoltification process as seen in Atlantic salmon (Salmo salar)
High fish density delays wound healing in Atlantic salmon (Salmo salar)
In this study, we look closer at how high fish densities influence wound repair mechanisms in post-smolt Atlantic salmon. The fish were wounded with a 5 mm skin punch biopsy needle and stocked at two different densities, a high fish density (100 kg/m3) treatment and a low fish density treatment (20 kg/m3) serving as the control. The healing wounds were followed for 57 days with samples taken 1, 3, 7, 14, 36, 43 and 57 days post wounding. The transcriptomic analysis suggests that high fish density enhance inflammation and represses cell proliferation, tissue secretion and collagen synthesis in the healing wounds. The histological analysis further showed delayed epidermal and dermal repair in the high fish density treatment compared to control. The overall wound contraction was also altered by the treatment. In conclusion, high fish density enhances immune responses and delay tissue repair, which ultimately results in delayed wound healing.High fish density delays wound healing in Atlantic salmon (Salmo salar)publishedVersio
Daily endocrine profiles in parr and smolt Atlantic salmon.
To elucidate possible mechanisms behind the endocrine control of parr-smolt transformation, the daily plasma profiles in thyroid hormones (TH; free thyroxine (FT(4)), total thyroxine (TT(4)), and total 3,5,3'-triiodothyronine (TT(3))), growth hormone (GH) and cortisol were studied in Atlantic salmon parr and smolts under simulated-natural winter (8 L:16D) and spring (16.5 L:7.5D) photoperiods, respectively. Overall, TT(4), TT(3) and GH levels were higher in smolts than in parr, whereas FT(4) levels fluctuated within the same range in parr and smolts. Significant diurnal changes in plasma TH were present in parr. Both FT(4) and TT(4) levels increased during the photophase and decreased during the scotophase, while TT(3) levels followed an inverse pattern. Growth hormone showed no significant changes in parr. Changes in FT(4), TT(4), GH, and cortisol, but not TT(3), levels, were observed in smolts with peak levels during both the photophase and scotophase for FT(4), TT(4) and GH. Plasma cortisol was not assayed in parr but in smolts the peaks were associated with dusk and dawn. In addition to the general increases in TH, GH and cortisol, the distinct endocrine differences in nighttime levels between parr in the winter and smolts in the spring suggest different interactions between TH, GH, cortisol and melatonin at these different time points. These spring scotophase endocrine profiles may represent synergistic hormone interactions that promote smolt development, similar to the synergistic endocrine interactions shown to accelerate anuran metamorphosis. The variations in these diurnal rhythms between parr and smolts may represent part of the endocrine mechanism for the translation of seasonal information during salmon smoltification
Free plasma thyroxine levels in coho salmon, Oncorhynchus kisutch, during parr-smolt transformation : Comparison with total thyroxine, total triiodothyronine, and growth hormone levels
Free plasma thyroxine (FT4) levels were measured in coho salmon, Oncorhynchus kisutch, during parr-smolt transformation (smoltification) using an equilibrium dialysis system followed by a radioimmunoassay. The FT4 data were correlated to total plasma thyroxine (TT4), triiodothyronine (TT3), and growth hormone (GH). Plasma samples were taken weekly from early April to late May, when the salmon where released from the hatchery. Free thyroxine and GH levels increased gradually through smoltification. TT4 levels increased significantly in mid-April and in mid-May. TT3 levels increased in April and remained elevated until late-May after which they declined to the lowest levels. During the first increase in TT4 levels, FT4 levels remained low and TT3 levels did not increase until FT4 levels increased in late-April. In addition, after TT4 levels decreased in late May, FT4 levels remained elevated. These data show that there are differences between the plasma FT4 and TT4 profiles during smoltification. Nevertheless, regression analysis indicates that FT4 levels are highly correlated to the increases in the levels of GH (r=0.73) and TT4 (r=0.70). In addition, GH is less correlated to TT4 and TT3 (r = 0.24 and r = -0.46, respectively) compared with FT4 (r = 0.73), suggesting a close relationship between the increases of FT4 and GH. In addition, these data suggest that this method of measuring free plasma thyroxine may provide a new tool for studying the timing of thyroid hormone action and regulation during parr-smolt transformation in salmonids
High fish density delays wound healing in Atlantic salmon (Salmo salar)
In this study, we look closer at how high fish densities influence wound repair mechanisms in post-smolt Atlantic salmon. The fish were wounded with a 5 mm skin punch biopsy needle and stocked at two different densities, a high fish density (100 kg/m3) treatment and a low fish density treatment (20 kg/m3) serving as the control. The healing wounds were followed for 57 days with samples taken 1, 3, 7, 14, 36, 43 and 57 days post wounding. The transcriptomic analysis suggests that high fish density enhance inflammation and represses cell proliferation, tissue secretion and collagen synthesis in the healing wounds. The histological analysis further showed delayed epidermal and dermal repair in the high fish density treatment compared to control. The overall wound contraction was also altered by the treatment. In conclusion, high fish density enhances immune responses and delay tissue repair, which ultimately results in delayed wound healing