Morphogenesis of Mouse Mammary Epithelium In Vivo in Response to Biomatrix Prepared from a Stimulatory Fetal Mesenchyme

Insoluble "biomatrix" of mesenchyme is a stimulator of mammary cell differentiation in vitro , but its effect in the morphogenesis is unknown. Fetal salivary mesenchyme induces intense local duct formation when implanted into adult mammary gland. We have therefore tested whether biomatrix prepared from fetal salivary mesenchyme retains this abillity to stimulate duct formation in vivo . Salivary mesenchyme isolated from mouse fetuses at 13.5–14.0 days of gestation, extracted sequentially with water and with 1 M NaCl, then digested with DNAse and RNAse was implanted into mammary glands of female mice and left for periods of 1–35 days. In approximately 40% of recipients, the local epithelium either formed cyst like structures, or else "spikes" of mammary epithelium penetrated the matrix forming a simplified ductwork inside it. Similar responses were elicited by salivary mesenchyme killed by freezing and also by biomatrix prepared from fetal mammary fat pad precursor tissue, mesenchyme of fetal lung, and fetal heart, liver, and brain. However when mesenchyme was either fixed with glutaraldehyde or sonicated and embedded in polymer blocks before implantation, no epithelial response was noted. These observations suggest that the biomatrix provides a passive scaffolding that contributes to morphogenesis of mammary ducts, is insufficient to support normal morphogenesis.     

Timers in Early Development of Sea Urchin Embryos

To elucidate the timing mechanisms in the early development of sea urchin embryos, we measured the times of initiation of the first four cleavages, of ciliary movement, of primary mesenchyme cell ingression, and of gastrulation at four temperatures ranging from 11 to 20°C. The times of cleavage and of initiation of ciliary movement showed similar temperature dependency, indicating that these events may be controlled by a common timer (the first timer). Although batches of eggs often showed variation in the period between fertilization and the first cleavage, their subsequent cleavages were more regular. This indicates that the first timer may not start at fertilization. The ingression of mesenchyme cells and the onset of gastrulation showed similar temperature dependency that was higher than that of other events, suggesting the existence of a second timer. Temperature shift experiments indicate that the second timer starts at the mid-blastula (the 8–9th cleavage) stage when divisions of blastomeres become asynchronous.     

RBEs of Thermal Neutron Capture Therapy and 10B(n,α)7 Li Reaction on Melanoma-Bearing Hamsters

Using Greene's melanoma transplanted into Syrian (golden) hamsters, we determined the relative biological effectiveness (RBE) of thermal neutron capture therapy (TNCT) using ¹⁰B-paraboronophenylalanine (¹⁰B-BPA) in comparison with a 9-MeV electron beam. We also obtained the RBE of the ¹⁰B(n,α)⁷Li reaction by calculation based on summed dose data from TNCT. Throughout this study, the Kyoto University Research Reactor was used as the source for thermal neutrons; the reactor was specially altered to attain a low contamination level both for gamma-rays and fast neutrons. ¹⁰B-BPA was administered 8 hours before thermal neutron irradiation to the hamsters with melanoma. The tumor was then irradiated at 5 MW for 90 minutes. The absorbed dose from this TNCT was calculated by the method of Fairchild and Goodman (Phys. Med. Biol. 1966; 2:15–30). The RBEs of the TNCT and the ¹⁰B(n,α)⁷Li reaction obtained by the tumor growth delay time (TGDT) method were 2.22 and 2.51, respectively, at 10.5 days of TGDT. These RBE values varied with TGDT and the absorbed dose. The RBE value of TNCT had a peak at 7.0 days of TGDT; that of the ¹⁰B(n,α)⁷Li reaction was higher at a low absorbed dose level and lower at a high absorbed dose level.     

Enhanced Melanogenesis Induced by Tyrosinase Gene-Transfer Increases Boron-Uptake and Killing Effect of Boron Neutron Capture Therapy for Amelanotic Melanoma

Specific and powerful cancer killing effect for melanoma by boron neutron capture therapy (BNCT) using DOPA analogue, ¹⁰B-p-boronophenylalanine (¹⁰B-BPA), has been established, but amelanotic melanoma is insufficiently responsive to ¹⁰B-BPA BNCT in comparison with actively melanin-producing melanoma. Although the accumulation mechanism of ¹⁰B-BPA within melanoma was not established, we have recently obtained findings suggesting that melanin monomers, key intermediates for melanin polymer formation, play a critical role in ¹⁰B-BPA accumulation. In addition, there are some kinds of human amelanotic melanomas, such as MEL2A, in which expression of tyrosinase is repressed or lacking though tyrosinase-related protein (TRP)-l and TRP-2 are well expressed. Thus, by using a similarly tyrosinase-lacking mouse amelanotic melanoma cell line, A1059, we constructed TA1059 cells by transfecting human tyrosinase-cDNA into these cells. TA1059 cells acquired higher DOPA-oxidase and DOPAchrome tautomerase activity as well as eumelanin content at even higher levels than those of B16F10 cells. TA1059 cells showed about 2.5 times higher ^p-boronophenylalanine (BPA) uptake than A1059 cells in culture. In animal experiments, by using these cell lines, tumor growth of TA1059 was significantly suppressed by ¹⁰B-BPA BNCT as compared with A1059. These findings indicate that the induction of active melanin biosynthesis by melanogenic gene-transfer effectively improves the treatment of amelanotic melanoma by BNCT.     

Accelerated growth rates in late‐hatched Rhinoceros Auklet Cerorhinca monocerata chicks depend on food conditions and growth stage: an experimental approach

In some bird species, the survival of chicks hatching later in the season is lower than those hatched earlier due to increased risk of predation and a seasonal decline in feeding conditions. To reduce these risks, it might be advantageous for late‐hatched chicks to grow faster and hence fledge at younger age. In this experimental study, the growth rates of early‐ and late‐hatched Rhinoceros Auklet Cerorhinca monocerata chicks were compared under average and poor food supplies in captivity. Controlling for potentially confounding effects of chick mass at 10 days old, chick age and nest‐chamber temperature, late‐hatched chicks had higher wing growth rate than early‐hatched chicks before attaining the minimum wing length required for fledgling under both average and poor food supplies. After attaining the minimum wing length, however, late‐hatched chicks had a lower fledging mass, indicating a potential cost that could diminish the early advantage of fast wing growth.     

Locking out predators by silk,a new counterattack behaviour in a social spider mite

1. A type of arms race that includes predation, counterattacks and cross‐counterattacks occurs between the phytophagous mite Stigmaeopsis nanjingensis (Ma et Yuan), which lives in self‐woven nests and exhibits cooperative sociality, and its specialised phytoseiid mite predator, Typhlodromus bambusae Ehara. 2. First, the efficiency of the S. nanjingensis (prey) counterattacking T. bambusae (predator) was observed. The prey females frequently locked the immature predators out of their nests using silk web, and the predators subsequently died of starvation. Furthermore, the prey males often killed immature T. bambusae mites after they invaded the nests. 3. This reversal of roles in the predator–prey system was then re‐reversed (returned to a normal state) by the behaviour of T. bambusae females. Immature predators could maintain their predacious natures due to the presence of attending adult females, which are able to cope with the prey counterattack behaviours.     

Studies on red pigments excreted by cells of Chlorella protothecoides during the process of bleaching induced by glucose or acetate II. Mode of formation of the red pigments

In parallel with the studies reported in the preceding paper(I), the modes of production of characteristic red pigmentsby Chlorella protothecoides cells were investigated under variousculture conditions, (i) During the course of "acetate-bleaching"of algal cells, excretion of red pigments in the medium proceededwith simultaneous disappearance of chlorophyll from algal cells.The total amount (weight) of the red pigments excreted intomedium was slightly less than that of the chlorophyll lost.No red pigment was detectable within the bleaching algal cells.Carotenoids were found to increase or remain nearly constantin their quantities per culture during the process of bleaching,(ii) In a later phase of "glucose-bleaching" some red pigmentswere found to be present inside as well as outside the algalcells, and the excreted pigments underwent further changes turningcolourless, (iii) Both the production of red pigments and disappearanceof chlorophyll were suppressed by light and this light effectwas insensitive to CMU. (iv) During the process of "regreening"of "glucose-bleached" algal cells, no production of red pigmentswas observed either in or outside the algal cells. Based on these results we concluded that the red pigments areproduced from chlorophyll during the bleaching process of algalcells induced by an organic carbon source. (Received July 23, 1968; )     

Bioelectric Control of Locomotion in the Ciliates*†

SYNOPSIS. Locomotor behavior in the ciliate protozoa is controlled by the cell membrane through electrophysiological principles already familiar in receptor, nerve, and effector cells of the metazoa. This is illustrated by the avoiding reaction (15). When the membrane of the anterior part of the ciliate receives a mechanical stimulus, as during collision, it permits a local influx of Ca⁺⁺. This constitutes a receptor current which depolarizes the remaining cell membrane by electrotonic spread. Depolarization causes a secondary transient increase in the calcium conductance of the entire cell membrane, and a general influx of Ca⁺⁺ occurs. The resulting increase in concentration of intracellular Ca⁺⁺ activates a reorientation (“reversal”) of the ciliary power stroke, causing the organism to swim backward. Forward locomotion is restored as the resting concentration of intracellular Ca⁺⁺ in the cell cortex is restored by diffusion, active extrusion, or intracellular sequestering. The control and coordination of locomotion in ciliates depend on several factors in addition to the excitable properties of the membrane. These include the sensitivities of the ciliary apparatus to intracellular concentrations of calcium and other regulating substances, the anatomical distribution of sensory receptor properties of the cell membrane, and the cable properties of the cell which permit electrotonic spread of graded potential signals without need of all-or-none conducted signals.     

Studies on nucleic acids in chloroplasts isolated from Chlorella protothecoides

1. 1. Subcellular fractions of Chlorella protothecoides were separatedby fractional centrifugation of the algal cell homogenate inmixtures of cyclohexane and CCl₄. The base composition, meltingprofiles and IRC-50 column chromatographic patterns of DNA preparationsfrom the chloroplast and non-chloroplast fractions were examined.It was shown that the algal chloroplast contains at least oneDNA species which is different from the nuclear DNA.
2. 2. RNApreparations from the subcellular fractions were subjectedtoMAK column chromatography, sucrose density gradient centrifugationand analysis for base composition. It was demonstrated thatthe chloroplast contains ribosomal RNA and soluble RNA. Twocomponents of the chloroplast ribosomal RNA were found to havethe same patterns as those of the E. coli ribosomal RNA in MAKcolumn chromatography and zone centrifugation. The major componentof the chloroplast ribosomal RNA was distinctly different fromthat of the non-chloroplastic (cytoplasmic) ribosomal RNA inall properties examined.

¹This work was partly reported at the Symposium on Mitochondriaand Chloroplasts as Self-duplicating Units sponsored by theBotanical Society of Japan in August, 1966, and at the Symposiumon Biogenesis of Subcellular Particles, the 7th Internatl. Congressof Biochemistry, Tokyo, 1967.