THE OCCURRENCE AND POSSIBLE SIGNIFICANCE OF HAEMOGLOBIN IN THE CHROMOSOMAL REGIONS OF MATURE ERYTHROCYTE NUCLEI OF THE NEWT TRITURUS CRISTATUS CRISTATUS

Absorption measurements in violet light (λ 4047 A) of thin sections of mature newt erythrocytes have indicated the presence of a haem compound, probably haemoglobin, within the chromosomal regions of the nucleus. The amount is about 45 per cent of that in the cytoplasm. The possible significance of this nuclear haemoglobin in determining nuclear structure is discussed in terms of the electrostatic interaction of haemoglobin and nucleohistone.     

LARVAL GROWTH AND THE INDUCTION OF METAMORPHOSIS OF A TROPICAL SPONGE-EATING NUDIBRANCH

The Hawaiian dorid nudibranch Hypselodoris infucata (Rppell& Leuckart, 1828) was reared to metamorphosis in the laboratory.Egg diameter averaged 88 µm and veligers hatched, afterabout 5 days at 25°C, with a coiled shell averaging 149µm in length. Larvae fed on phytoplankton grew to a maximumshell length of 306 µm in about 15 days. Larval growthwas affected by both quality and quantity of the algal diet.Some larvae were competent to metamorphose 16 days post-hatchingat 26°C, and competence could be retained for at least oneweek. Metamorphosis is complete within 24 hours of exposureto an inducer. At least three species of sponge, Halichondriacoerulea, Sig-modocia sp., and Tedania macrodactyla, in additionto the nudibranch's adult prey species, Dysidea sp., inducedmetamorphosis of competent larvae. Primary films grown on glassslides also induced metamorphosis in some larvae, as did 20µM excess potassium ions in seawater. These data suggestthat nonspecific induction of metamorphosis occurs in this specieseven though the adult nudibranchs are highly prey specific.This implies that in the field, H. infucata find Dysidea sp.after settlement and metamorphosis Present address: Dept of Genetics and Development, College ofPhysicians and Surgeons of Columbia Univeisity, 701 West 168thStreet, NewYork, 10032, USA (Received 22 June 1987; accepted 3 March 1988)     

THE DELAY IN OVULATION PRODUCED BY pp'-DDT AND ITS POSSIBLE SIGNIFICANCE IN THE FIELD

A significant correlation between pp'-DDT intake by the female Bengalese Finch Lonchuro striata and delay in ovulation is reported. Linked with earlier work showing that pp'-DDT can cause inhibition of the testicular growth and secondary sexual characters of cockerels, it is deduced that in this context the site of action of the pp'-DDT is probably the pituitary or hypothalamus. Inhibition of the secretion of the pituitary hormones could explain the reported recent increase in egg breakages by predatory birds. It is also probable that organochlorine pesticides are responsible for the late breeding of several species of birds reported in the early nineteen-sixties. This could affect a population in that large sublethal doses which double the time for egg laying could cause a double-brooded bird to be out of phase with the food supply for the late broods.     

THE OXIDATION-REDUCTION POTENTIAL OF THE LUCIFERIN-OXYLUCIFERIN SYSTEM

The oxidation-reduction potential of the Cypridina luciferin-oxyluciferin system determined by a method of "bracketing" lies somewhere between that of anthraquinone 2-6-di Na sulfonate (E_o ^'' at pH of 7.7 = –.22) which reduces luciferin, and quinhydrone (E_o ^'' at pH of 7.7 = +.24), which oxidizes luciferin. Systems having an E_o ^'' value between –.22 and +.24 volt neither reduce oxyluciferin nor oxidize luciferin. If the luciferin-oxyluciferin system were truly reversible considerable reduction and oxidation should occur between –.22 and +.24. The system appears to be an irreversible one, with both "apparent oxidation" and "apparent reduction potentials" in Conant''s sense. Hydrosulfites, sulfides, CrCl₂, TiCl₃, and nascent hydrogen reduce oxyluciferin readily in absence of oxygen but without luminescence. Luminescence only appears in water solution if luciferin is oxidized by dissolved oxygen in presence of luciferase. Rapid oxidation of luciferin by oxygen without luciferase or oxidation by K₃Fe(CN)₆ in presence of luciferase but without oxygen never gives luminescence.     

大鼠肝癌发生过程中转化生长因子-β1的表达及意义

为了进一步探讨转化生长因子-β1在肝癌发生中的作用和意义。本采用免疫组织化学ABC法,对二乙基亚硝胺（DEN）诱发大鼠肝癌发生过程中转化生长因子-β1（Transforming growth factor-β1,TGF-β1）表达情况进行了观察。结果显示;在正常大鼠肝脏,TGF-β1的表达只局限于血窦内皮细胞或枯否细胞,汇管区血管内皮细胞及胆管上皮细胞,肝细胞呈TGF-β1阴性表达,诱癌早期（4-8周）,大鼠肝小叶内除血窦内皮细胞或枯否细胞呈TGF-β1阳性表达外,可见少量散在分布的肝细胞呈TGF-β1阳性表达,阳性肝细胞胞质内可见棕褐色阳性反应颗粒,随着肝癌发展,TGF-β1阳性肝细胞逐渐增多,至诱癌晚期（18周）,癌结节内的大多数肝癌细胞呈TGF-β1阳性表达。本研究显示TGF-β1与肝癌的发生和发展密切相关。至诱癌晚期（18周）,癌结节内的大多数肝癌细胞呈TGF-β1阳性表达,本研究显示TGF-β1与肝癌的发生和发展密切相关。     

ON THE CONTROL OF THE RESPONSE TO SHADING IN THE BRANCHI? OF CHROMODORIS

The branchial plumes of Chromodoris respond, by contraction, to a decrease in light intensity. This response is obliterated by high temperatures (above 32°) and by direct sunlight, and is possible only within a limited range of alkalinity of the sea water. A concealing retraction of the whole gill-crown is reflexly determined by the self-contraction of the individual plumes under "optimal" conditions of light, temperature, and alkalinity. This protective response of the branchiæ is superimposed upon their simple system of fundamental activities (protrusion, retraction) apparently concerned with regulating the respiratory exchange of the nudibranch.     

PNEUMATIZATION OF THE CRANIUM OF THE ZEBRA FINCH TAENIOPYGIA CASTANOTIS

The process of cranial pneumatization in the Zebra Finch Taeniopygia castanotis is substantially similar to that described in the House Sparrow Passer domesticus , but is completed somewhat earlier. Full pneumatization of the cranium is usually attained between 138 and 153 days from hatching, though in some birds it may be retarded. A series of diagrams, representing 41 stages in the process, enables the ages of young birds to be established.