Impairment of Mobility in Endodermal Cells by FAK Deficiency

Focal adhesion kinase (FAK) is a novel nonreceptor protein tyrosine kinase that localizes in focal adhesions. It is expressed in a variety of cell types, and we reported earlier that its deficiency causes a decrease of mobility in mesodermal cells with enhanced formation of focal adhesions. With embryoid bodies generated from embryonic stem cells, we also observed a decrease of mobility in FAK-deficient endodermal cells with enhanced focal adhesion formation.     

Immune Response to Toxoplasma gondii

Peripheral blood leukocytes (PBL) from patients with toxoplasmosis were shown to be highly responsive to in vitro stimulation with Toxoplasma gondii extract as measured by incorporation of [³H]methylated thymidine. Analysis of Toxoplasma-specific proliferative cells in PBL by using monoclonal antibodies specific for human T cell subsets revealed that the Toxoplasma-specific proliferation response of PBL from the patients was mediated by Leu 1, Leu 3a positive cells, that is, helper/inducer T cells. Tests for the Toxoplasma-specific proliferation response may provide a readily available method for the diagnosis of congenital toxoplasmosis, especially during the newborn period.     

Developmental changes in the calcium currents in embryonic chick ventricular myocytes

Summary Using the patch-clamp technique, we recorded whole-cell calcium current from isolated cardiac myocytes dissociated from the apical ventricles of 7-day and 14-day chick embryos. In 70% of 14-day cells after 24 hr in culture, two component currents could be separated from totalI _Ca activated from a holding potential (V _h) of –80 mV. L-type current (I _L) was activated by depolarizing steps fromV _h –30 or –40 mV. The difference current (I _T) was obtained by subtractingI _L, fromI _Ca.I _T could also be distinguished pharmacologically fromI _L in these cells.I _T was selectively blocked by 40–160 m Ni²⁺, whereasI _L was suppressed by 1 m D600 or 2 m nifedipine. The Ni²⁺-resistant and D600-resistant currents had activation thresholds and peak voltages that were near those ofI _T andI _L defined by voltage threshold, and resembled those in adult mammalian heart. In 7-day cells,I _T andI _L could be distinguished by voltage threshold in 45% (S cells), while an additional 45% of 7-day cells were nonseparable (NS) by activation voltage threshold. Nonetheless, in mostNS cells,I _Ca was partly blocked by Ni²⁺ and by D600 given separately, and the effects were additive when these agents were given together. Differences among the cells in the ability to separateI _T andI _L by voltage threshold resulted largely from differences in the position of the steady-state inactivation and activation curves along the voltage axis. In all cells at both ages in which the steady-state inactivation relation was determined with a double-pulse protocol, the half-inactivation potential (V _1/2) of the Ni²⁺-resistant currentI _L averaged –18 mV. In contrast,V _1/2 of the Ni²⁺-sensitiveI _T was –60 mV in 14-day cells, –52 mV in 7-dayS cells, and –43 mV in 7-day NS cells. The half-activation potential was near –2 mV forI _L at both ages, but that ofI _T was –38 mV in 14-day and –29 mV in 7-day cells. Maximal current density was highly variable from cell to cell, but showed no systematic differences between 7-day and 14-day cells. These results indicate that the main developmental change that occurs in the components ofI _Ca is a negative shift with, embryonic age in the activation and inactivation relationships ofI _T along the voltage axis.     

Ultrastructure of the endolymphatic sac in the mouse.

The ultrastructure of the endolymphatic sac (ES) in the mouse was examined by light and electron microscopy. This organ was divided into three parts: proximal, intermediate and distal. In the proximal portion of the ES, the epithelium consisted of thin squamous cells. The epithelial cells had acquired basolateral processes, numerous small vesicles and well-developed Golgi apparatus. In the intermediate portion, the epithelium consisted of columnar or cuboidal cells. The epithelial cells could be classified into two types: type I and type II. The type I cells had abundant microvilli, pinocytotic vesicles, vacuoles, multivesicular bodies, lysosomes and mitochondria. The type II cells had fewer numbers of these organelles. A few free-floating cells could be observed in the lumen of this intermediate portion, most of which were macrophages. In the distal portion, the epithelium consisted of squamous or cuboidal cells. The epithelial cells had a few cytoplasmic organelles. In the ultrastructural study, each portion of the mouse ES was found to have a very distinct morphological feature. It was suggested that each of these three portions has a different function.     

Induction of a novel long-chain acyl-CoA hydrolase in rat liver by administration of peroxisome proliferators

The activity of long-chain acyl-CoA hydrolase in rat liver was increased by the administration of peroxisome proliferators, such as ethyl p-chlorophenoxyisobutyrate, di(2-ethylhexyl)phthalate or acetylsalicylic acid. The induced activity was mainly confined in the soluble fluid after the subcellular fractionation. The enzyme was purified nearly to homogeneity from livers of rats treated with di(2-ethylhexyl)phthalate. The specific activity of the final preparation was 247 mumol palmitoyl-CoA hydrolyzed min-1 mg protein-1. The molecular weight of the native enzyme was estimated to be 150 000 by gel filtration and that of the subunits was 41 000 by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The activity of the enzyme was not increased but inhibited by bovine serum albumin or Triton X-100. The molecular and catalytic properties of the enzyme suggest that the induced enzyme was different from mitochondrial and microsomal long-chain acyl-CoA hydrolyses in liver.     

Cytological changes and DNA and protein synthesis in parthenogenetically activated sea urchin eggs

Summary The present study deals with cytological observations, DNA and protein synthesis in artificially activated sea urchin eggs. The eggs were activated by means of Loeb's double treatment with butyric acid and hypertonic sea water. Most of the eggs ofHemicentrotus pulcherrimus divided when the chromosomes duplicated after formation of the first monaster and other eggs divided at a later cell cycle. In the eggs ofTemnopleurus toreumaticus, however, haploid division at the first cell cycle was observed predominantly.Activated eggs that were treated for 25 min with hypertonic sea water showed a marked uptake of³H-thymidine during the two periods of 30–40 min and 90–100 min after the double treatment. These periodic changes in the³H-thymidine uptake paralleled morphological changes within the nucleus. However, these periods of increased uptake were not observed in the eggs treated with hypertonic sea water for 60 min. During exposure to hypertonic sea water, the³H-thymidine-uptake by eggs activated with butyric acid decreased gradually. When the uptake of¹⁴C-valine by eggs was measured, a very low level was seen in unfertilized eggs. The level of uptake increased strikingly when the eggs were activated with butyric acid but was suppressed by the hypertonic treatment. However, removal of the eggs to sea water allowed the uptake to return to the former high level. This pattern suggests that the hypertonic treatment has an inhibitory effect on the synthesis of protein (or enzymes) which obstruct cleavage induction.     

Light-dependent development of thermoluminescence, delayed emission and fluorescence variation in dark-grown spruce leaves

Thermoluminescence profiles of spruce leaves grown under various light or dark conditions were measured after excitation at a low temperature (−70 to −20 °C) by 1-min illumination with red light, and the following results were obtained. Mature spruce leaves showed five thermoluminescence bands at −30, −5, +20, +40 (or +35) and +70 °C (denoted as Z_v, A, B₁, B₂ and C bands, respectively), but dark-grown spruce leaves with a similar chlorophyll content showed only two bands, at −30 and +70 °C (the Z_v and C bands) and were devoid of the three other bands (the A, B₁ and B₂ bands). On exposure of the dark-grown leaves to continuous red light, the A, B₁ and B₂ bands were rapidly developed, and the development was accompanied by enhancement of delayed emission, fluorescence variation and the Hill activity (photoreduction of 2,6-dichlorophenolindophenol with water as electron donor). It was demonstrated that the dark-grown spruce leaves are devoid of the water-splitting system in Photosystem II, and that the latent water-splitting activity is rapidly photoactivated by exposure of the leaves to continuous red light. These results on the gymnosperm spruce leaves, in which greening proceeds in complete darkness, being independent of the development of the water-splitting system in light, were discussed in relation to previous observations on angiosperm leaves, in which both greening and the activity generation proceed in the light.     

Multiple-flash development of thermoluminescence bands in dark-grown spruce leaves

Spruce leaves greened in darkness were devoid of three of the five thermoluminescence bands found for mature leaves. These bands were developed rapidly by exposure of the dark-grown leaves to continuous light. The development of these bands was studied by illumination with repetitive flashes at varied intervals. Flashes at intervals of 1 s were the most effective in inducing these bands. Those at shorter or longer intervals were less effective. It was deduced from these data that the development of these bands is a multiquantum process which involves at least two photo-events with a dark reaction between them.     

Population abundance gradient of Inurois punctigera along altitude

A winter geometrid moth, Inurois punctigera, shows sympatric and genetically isolated seasonal populations (i.e. early‐ and late‐winter populations) in the cold regions of Japan, whereas it shows only mid‐winter populations in the warm regions. Variation in adult flight phenology on a large geographic scale along latitudinal environmental gradients has been described, but the phenological variation on a more local scale along altitudinal environmental gradients has not yet been characterized. In the present study, we assessed the flight phenology at high‐ and low‐elevation areas in Mt. Rokko, Hyogo, Japan. First, we revealed that flight period was not disrupted in mid‐winter, even at high‐elevation areas (>660 m) but the population abundance was much lower in high‐elevation areas than in low‐elevation areas. Then, in the following two seasons, we investigated I. punctigera abundance, winter harshness (i.e. winter temperature) and their host plant abundance in nine closely located stations in Mt. Rokko. A generalized linear mixed model analysis indicated a greater effect of winter temperature on I. punctigera abundance compared to available food resources, suggesting that differences in winter harshness among elevation shapes the gradient of I. punctigera abundance along altitude. Our findings suggest that harsh conditions during winter function as selective agents on mid‐winter types of I. punctigera, and this could be involved in the divergence between sympatric early‐ and late‐winter populations of I. punctigera.