Selection in segregating generations of autogamous species. I. Selection response for combined selection

Summary The response to selection is determined by the genetic and nongenetic variance, the selection intensity, and the size of the experiments. If, in pure line breeding, selection starts in segregating generations, the gain depends on the relation of additive to epistatic variance. The gain can be increased if an index is constructed using the information from relatives. From animal breeding this kind of selection is known as combined selection. In this paper the optimal number of families and subfamilies is determined that will maximise the selection response by combined selection for a fixed total size of experiments. The composition of the genetic variance has a imited influence on the optimal size of the progenies. If epistatic variance is important, then the number of F₂ families has to be reduced and the number of F₃ families and F₄ families must be increased. The same is true if the nongenetic variance is increased.     

Studies on the Maturation and Spawning of Milkfish Chanos chanos Forsskal in a Photoperiod-Controlled Room

Progress in propagation of milkfish has been impeded by the shortage of mature broodstock. This study was a first step toward revealing the environmental cues for the maturation of milkfish. Experiments were carried out during 1978-1985 in an indoor tank (5.2 × 4.8 × 13 m) under photoperiod control and in an outdoor tank (63 × 5.4 × 13 m). In two controlled, long-photoperiod regime experiments, 86 and 83% of the fish matured, the highest percentages yet reported. In these experiments, milkfish matured one month earlier than the normal spawning season, two months after the fish were exposed to the long daylight regime. Only 21% of the fish under a natural photoperiod regime in the outdoor tank matured. Results of the current study suggest that a change and increase in photoperiod are necessary for the onset of maturation.     

X-Chromosomal Monosomy (77, XO) in a Doberman Pinscher With Gonadal Dysgenesis

A 6-month-old stunted female Doberman Pinscher was found to have a 77,X0 chromosomal complement. The ovaries were small, consisting primarily of interstitial-type cells and solid epithelial cords. The dam, sire, and a male littermate had normal karyotypes.     

Pathophysiologische und pathomorphologische Veränderungen an Ratten nach chronischer Verabreichung und anschliessender Mobilisierung des gespeicherten DDT im Hunger

Zusammenfassung 48 erwachsene männliche Ratten wurden in drei Gruppen eingeteilt und erhielten während sieben Monaten eine Kost mit 100 bzw. 200 ppm DDT (DDT dem Futter in Substanz beigemischt, nicht in öliger Lösung verabreicht) zur Anreicherung von DDT im Fettgewebe (Kontrollgruppe ohne DDT). Die DDT-Zufuhr wurde dann abgesetzt und jede Gruppe in zwei Untergruppen eingeteilt, von denen jeweils die eine einer 24-tägigen Hungerperiode unterworfen wurde, um den wesentlichen Teil des Körperfetts zu mobilisieren und dadurch das gespeicherte DDT freizusetzen. Die Tiere der anderen Untergruppen wurden ad libitum weitergefüttert. Anschließend wurden alle Tiere zur Objektivierung einer etwaigen Beeinflussung der Funktion des Nervensystems einem Labyrinthversuch und einem Drehstabtest unterworfen. Zum Abschluß des Versuchs wurden die Tiere getötet und Herz, Leber, Niere, Lunge und Gehirn histologisch untersucht.Ergebnisse: Gewichtsentwicklung, Futterverwertung, Überlebenszeit und allgemeines Verhalten der Tiere wurden durch die chronische DDT-Verabreichung und anschließende Mobilisierung im Hunger nicht sicher beeinflußt. Beide psychophysiologischen Tests dagegen deuten auf einen Mobilisierungseffekt hin, der über den Einfluß der chronischen DDT-Gaben hinausgeht. Auch histopathologisch gibt sich ein Mobilisierungseffekt nach Auffütterung mit DDT durch geringgradige Atrophie von Leberzellbalken, durch Haemosiderinablagerungen in den Sinusuferzellen und Leberepithelien und durch Vacuolisierung einzelner Ganglienzellen zu erkennen. Als Folge der chronischen DDT-Verabreichung treten in der Milz Haemosiderinablagerungen in der roten Pulpa auf, die eigenartigerweise bei den Tieren, die eine Hungermobilisierung durchgemacht haben, nicht mehr gesehen werden.Insgesamt lassen die Ergebnisse des Versuchs einen Mobilisierungseffekt, dessen Wirkung wesentlich über den Einfluß einer entsprechenden chronischen DDT-Gabe hinausgeht, der also besondere Beachtung verdienen würde, bei einem Futter mit 100 bzw. 200 ppm DDT auch bei forcierter Hungermobilisierungnicht erkennen.

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Summary Fourty eight male adult rats were devided into 3 groups. During 7 months they were fed with a diet containing 100 and 200 ppm DDT, respectively (control group without DDT) for accumulation of DDT in the body fat. The DDT was mixed into the diet in substance, not solved in oil or other lipids.After seven months the administration of DDT was terminated. Each of the groups was devided into two subgroups. One subgroup received a normal stock-diet ad libitum, the other the same diet in restricted amounts in order to mobilize body fat and subsequently the stored DDT. This mobilizing period was conducted over 24 days. After this time the subgroups with restricted food-intake had lost about 170 g of body weight. The body weight of the ad libitum-subgroup remained nearly constant.To objectivate effects of the mobilisation of DDT on the function of the central nervous system the rats were subjected to labyrinthtests and tests with turning sticks. Moreover the general behaviour of the rats was observed. Finally the animals were decapitated and heart, liver, kidneys, lung, spleen and brain were examined histologically.Results: weight-gain, food efficiency, surviving, and general behaviour remained uneffected by long-time administration of DDT and following mobilisation by inanition. But in both psychophysiological tests an effect of the DDT-mobilisation by inanition could be shown. Later on the DDT-mobilisation seems to cause some slight morphological alterations: Slight atrophia of liver cells, accumulation of hemosiderin in stellata cells of kupffer and in the liver cells, and vacuolizing of ganglion cells. Following the chronic administration of DDT, accumulation of hemosiderin in the red pulp of the spleen occurred. However, peculiarly this effect was not observed in rats after mobilizing of DDT by inanition.Altogether the results of the experiments show that the so called mobilisation-effect of accumulated DDT by inanition after long time administration of 100 and 200 ppm DDT, respectively, is not an important effect, but seems to be harmless under our experimental conditions.