Effects of the brachyury (T) mutation on mitotic activity in the neural tube.

Mitotic activity in the neural tube was examined in +/+, $\text{T}\text{+}$ and $\text{T}\text{T}$ mouse embryos. The number of mitotic figures per unit area of ependymal layer (area index) was higher in $\text{T}\text{+}$ embryos than in +/+ embryos. In +/+ embryos, area index was higher in the dorsal part of the neural tube than in the ventral part, whereas this pattern is disordered in $\text{T}\text{+}$ embryos. In $\text{T}\text{T}$ embryos, these values fluctuate. The process of nuclear migration accompanying cell division seems to be normal in the neural tube of $\text{T}\text{+}$ and $\text{T}\text{T}$ embryos.     

Developmental analysis of lethal effects of homozygosity for the C25H deletion in the mouse

This report describes the phenotype of the c^25H lethal homozygote. Our studies have shown that embryos homozygous for c^25H fail to implant and to induce a decidual reaction. Embryos arrested at the three- to six-cell stage were considered to be c^25H homozygotes because of their homogeneous stage of arrest and because they were present in the appropriate proportion in preimplantation litters from $\text{c}{}^{\mathrm{ch}}\text{c}{}^{\mathrm{25H}}\text{×}\text{c}{}^{\mathrm{ch}}\text{c}{}^{\mathrm{25H}}$ matings. Mitosis appeared to be disturbed in the arrested embryos.     

Inhibition of DNA synthesis in embryonic mouse retina as a result of gene interaction.

It has been shown by autoradiography using ³H-thymidine that 11-day mouse embryos doubly homozygous for the autosomal recessive genes fidget (gene symbol fi) and ocular retardation (or), have three to five times fewer labelled nuclei in their retina anlages as do normal (genotype +/+ +/+) embryos singly homozygous for fidget (+/+ $\text{fi}\text{fi}$) or ocular retardation (+/+ $\text{or}\text{or}$). In 11-day embryos of +/+ +/+, +/+ $\text{fi}\text{fi}$ and +/+ $\text{or}\text{or}$ genotypes the labelled nuclei are localized mainly in the inner zone of the retina anlage. However, in double homozygotes the indices of labelled nuclei were not significantly different in the inner and outer zones of the retina anlage. The retina anlage of 12-day double homozygote, $\text{fi}\text{fi}\text{or}\text{or}$, has practically no nuclei synthesizing DNA. Consequently, the mutant genes fi and or which prolong the G₁ period of the cell cycle in single homozygotes, act synergetically to stop DNA synthesis in the retina anlage cells of 12-day $\text{fi}\text{fi}\text{or}\text{or}$ embryos.     

The cell cycle and retinal histogenesis fidget mutant mice.

The autoradiographic method using [³H]thymidine has shown that the autosomal recessive mutant gene fidget (gene symbol fi) prolonging the presynthetic period of the cell cycle in the retinal anlage in homozygotes retards the transition of retinal cells to the differentiated state. Some retinal cells of normal embryos (+/+) start their transition to the differentiated state on the 11th day of embryogenesis, while in $\text{fi}\text{fi}$ embryos this process starts only on the 12th day. An active transition of retinal cells to the differentiated state especially in the peripheral zone of the mutant retina takes place 2 days later as compared to normal embryos. The number of differentiating cells in the retina of mutants at the stages of development studied is considerably lower as compared to the norm. The analysis of the cell cycle parameters in 15-day embryos has shown that in the mutants the retina is less mature as compared to +/+ embryos. The sequence of transition of various cell types to the differentiated state in the retina of $\text{fi}\text{fi}$ embryos is the same as in the norm. Gene fidget seems to interfere with proliferative rather than critical (quantal) cell cycles in the developing mouse retina.     

Cellular aspects of tolerance. VII. Inheritance of the resistance to tolerance induction

The half-lives of elimination ($\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$) of ¹³¹I-RGG from the body of normal A or Balb/c animals was much longer than the $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of SJL mice. At all ages, the $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of normal hybrids (A × SJL, SJL × A, Balb/c × SJL) was similar to or longer than that of the A or Balb/c parents. Thus, in terms of the $\text{T}\text{1}\text{2}$ of normal animals, the SJL responsiveness to ¹³¹I-RGG appeared to be a recessive trait. Tolerance could be induced in newborn animals and, in terms of $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, the degree of unresponsiveness at the age of 6 weeks, was the same in A, Balb/c, A × SJL, and Balb/c × SJL animals but was much shorter in SJL mice. Thus, in neonatally induced tolerance, the duration of tolerance was recessive for the SJL type. The average $\text{T}{}_{\mathrm{<mtext>built1</mtext><mtext>2</mtext>}}$ after tolerance induction in 3-week-old hybrids (A × SJL, SJL × A, Balb/c × SJL) was similar to that of the A or Balb/c parent, but by the 8th and 12th week it approached the average $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of the SJL parent. Comparing 8-week-old hybrids, the average $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was longest in A × SJL hybrids and identical in SJL × A and Balb/c × SJL mice. An examination of $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ distribution in various 8- and 12-week-old crosses and backcrosses revealed a fairly large proportion of individuals with a $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ which was intermediate between SJL and the other parent. There was a tendency for this number to decrease in 12 weeks as compared to 8-week-old mice. In 8-week-old mice, the number of animals with intermediate $\text{T}{}_{\mathrm{<mtext>built1</mtext><mtext>2</mtext>}}$ was smallest when SJL was the maternal animal [(SJL × A); SJL × (A × SJL); SJL × (SJL × A)]. There was no link between $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of tolerant animals and either the immunoglobulin allotype (MuAl/MuA2) or the C5 eniotype (MuB1 positive/MuB1 negative).     

Experimental studies on a mutant gene (e) preventing the differentiation of eye and normal hypothalamus primordia in the axolotl

The phenotype of axolotls (Ambystoma mexicanum) homozygous for the mutant gene e (“eyeless”) is different from normal in that (1) no optic vesicles develop in $\text{e}\text{e}$ embryos, (2) $\text{e}\text{e}$ larvae from posthatching onward are darker than normal white larvae, and (3) fully grown $\text{e}\text{e}$ animals are sterile.Experiments reported here show that eyelessness in $\text{e}\text{e}$ embryos results from a direct effect of the gene on presumptive forebrain ectoderm; not on the mesoderm that induces the ectoderm to form eyes. Homotopic grafts of normal presumptive ectoderm on $\text{e}\text{e}$ blastula hosts differentiated complete eyes, but reciprocally grafted embryos were always eyeless. Similarly, grafts of either $\text{e}\text{e}$ or normal presumptive prechordal mesoderm into normal hosts gave normal eyes, but in the mutant hosts no eyes developed. Thus the e gene affects only the ectodermal component of the inductive system for eye formation.Genetically eyeless (pigmented) cells, when interspersed prior to gastrulation among genetically eyed (albino) cells in the eye preprimordium, are induced to form clones of pigmented retinal epithelium in the albino host eye.The sterility of $\text{e}\text{e}$ larvae appears also to be due to a direct effect of the e gene on the ectodermal (neural plate) primordium of the hypothalamus. Grafts of normal cells which included the hypothalamic, but not the optic or anterior pituitary primordia, always restored fertility to $\text{e}\text{e}$ recipients.The mutant pigmentation phenotype was demonstrated to be a consequence of eyelessness and, therefore, an indirect effect of the gene. The pigment pattern of normal embryos from which both optic vesicles were removed resembles that of the mutants. In addition, implantation of a single full-sized, functional eye was able to restore the normal pigmentation, but not fertility, to $\text{e}\text{e}$ recipients.     

Cell surface antigens of totipotent mouse teratocarcinoma cells grown in vivo: their relation to embryo, adult, and tumor antigens.

Cell surface antigens on mouse embryonal carcinoma (or teratocarcinoma) cells were investigated by means of a syngeneic antiserum prepared against small-size embryoid bodies from the ascites form of the OTT 6050 transplantable teratoma. These embryoid bodies consist of embryonal carcinoma cells which are usually covered by a yolk-sac-like epithelium. The choice of immunogen was based on the previous demonstration [Mintz, B., and Illmensee, K. (1975) Proc. Nat. Acad. Sci. USA72, 3585–3589] that embryonal carcinoma cells from this specific source are euploid, developmentally totipotent, and completely reversible to normalcy. In indirect immunofluorescence tests, anti-embryoid-body serum reacted with both cell types of the immunogen and with two in vitro lines of embryonal carcinoma cells. Absorption of antiserum with a pure yolk sac carcinoma derived from the epithelial component of the embryoid bodies enabled assessment of reactivity with the embryonal carcinoma component of the immunogen: The absorption revealed that some antigens recognized on the embryonal carcinoma cells were shared by the yolk sac epithelial cells but that some antigens were present only on the embryonal carcinoma cells. The antigens were not shared by sperm, which failed to fluoresce with unabsorbed antiserum and were ineffective when tested as absorbents of antiserum reactivity against embryoid body target cells. Unfertilized eggs also failed to fluoresce. Preimplantation embryos gave immunofluorescence evidence of some antigens shared with embryonal carcinoma cells (and some with yolk sac cells) during cleavage, and in the blastocyst on both inner cell mass and trophoblast. Postimplantation embryos were also antigen-positive (at least through Day 6) in immunofluorescence tests on endoderm as well as ectoderm cells. Absorption of the antiserum with various normal adult tissues showed substantial cross-reactivity, especially with ovary and testis. Other tumors were tested, but only hepatoma cells grown in vitro were reactive, thereby indicating lack of any general tumor recognition in the antiserum. The above results with syngeneic immunizations demonstrate that known totipotent teratocarcinoma cells possess surface molecules which, while not universal on normal cells or tumors, are shared with many other tissues, including developmentally plastic cells of early embryos, developmentally restricted cells of later embryos, and various adult tissues. Immunofluorescence tests of cleavage-stage (Day 2) embryos from matings of $\text{+}\text{t}{}^{12}\text{×}\text{+}\text{t}{}^{12}$ heterozygotes, yielding 40% mutant $\text{t}{}^{12}\text{t}{}^{12}$ homozygotes lethal on Day 3, were uniformly positive on all the embryos, including mutants and normals. Therefore, under these conditions, no evidence was adduced to support the hypothesis that surface components required for normal early development might be coded by the wild-type allele of t¹².     

Ontogeny of the mammalian insulin receptor: Studies of human and rat fetal liver plasma membranes

Insulin binding to human fetal plasma liver membranes was studied in preparations segregated into three pools according to length of gestation: 15–18 weeks (Pool A), 19–25 weeks (Pool B), and 26–31 weeks (Pool C). Receptor numbers, calculated by extrapolation of Scatchard plots to the X axis, increased from 25 × 10¹⁰ sites per 100 μg protein in the youngest group (Pool A) to 46 × 10¹⁰ sites per 100 μg protein in Pool B. No further increase in receptor number was seen in Pool C. The affinity constant for insulin at tracer concentrations, $\text{K}{}_{\mathrm{<mtext>e</mtext>}}$ (“empty site”), was 1.53 × 10⁸M^?1 in Pool A and was only slightly higher than $\text{K}{}_{\mathrm{<mtext>f</mtext>}}$ (“filled site”). $\text{K}{}_{\mathrm{<mtext>e</mtext>}}$ was higher in Pool B, 1.75 × 10⁸M^?1, and in Pool C reached a value of 5.63 × 10⁸M^?1. In Pool C $\text{K}{}_{\mathrm{<mtext>f</mtext>}}$ was 2.3 × 10⁸M^?1. Insulin binding of liver plasma membranes from rat fetuses aged 14, 16, 18, and 21 (term) days and adults was also studied. Maximum binding capacity tended to increase with gestational age and was 130 × 10¹⁰ sites per 100 μg protein at term, which was in excess of that found in adult rats (89–90 × 10¹⁰). In addition, $\text{K}{}_{\mathrm{<mtext>e</mtext>}}$ increased from 0.75 × 10⁸M^?1 at 14 days to 3.02 × 10⁸M^?1 at term, a value higher than that found in pregnant and nonpregnant adults. Dissociation of insulin in the presence of high concentrations of insulin was significantly enhanced in tissues from 18-day and term fetuses and adults, but not in membranes from fetal rats aged 14 and 16 days. These data appear to indicate that site-site interactions are not present in early fetal existence. These changes in insulin binding with increased length of gestation are not ascribable to changes in relative proportions of hematopoietic and parenchymal tissue. Human fetal plasma liver membranes demonstrated elevated insulin binding with increased gestational age, but comparison of fetal and adult liver could not be done. However, newborn human infants have been shown to have a higher capacity for binding insulin to circulating monocytes than adults. Also, human fetuses apparently lack the capability to diminish monocyte receptors in the presence of hyperinsulinemia. These experiments show that an increase in insulin receptor binding capacity and affinity also occurs in the liver of the rat fetus at term as compared to the adult rat. The reasons and mechanisms underlying enhanced capacity for insulin binding by fetal and newborn members of human and rodent species are not known.     

In vitro development of early postimplantation rat embryos

Rat embryos explanted at $\text{7}\text{1}\text{2}$ or $\text{8}\text{1}\text{2}$post coitum were cultured throughout the major stages of organogenesis in a system of rotating bottles containing heat-inactivated, immediately centrifuged (I.C.) serum. About 80% of the $\text{8}\text{1}\text{2}\text{-}\text{day}$ explants and 50% of the $\text{7}\text{1}\text{2}\text{-}\text{day}$ explants developed a blood circulation in the yolk sac; in these embryos, organogenesis and growth rates were similar to those of embryos in vivo. In cultures continued for 4 or 5 days, many of the embryos developed 30–40 somites. There was little difference in the subsequent development of embryos cultured in maternal serum or male serum during the egg-cylinder stage except for a possible decrease in the frequency of normal axial rotation in embryos from the male serum. Development in rotator bottles was much better than in watchglass cultures.     

Development of teratomas from yolk sac of genetically sterile embryos

Yolk sac-derived teratomas are composed of various well-differentiated tissues. These tissues must be derived from multipotent cells. To exclude a germ cell origin for these teratomas we used $\text{Steel}\text{-}\text{Sl}\text{+}$ females copulated with $\text{Sl}\text{+}$ males. The embryos generated from such mating comprise 25% $\text{Sl}\text{Sl}$ sterile embryos, deficient in primordial germ cells, 25% normal embryos (+/+), and 50% heterozygotes ($\text{Sl}\text{+}$). The results indicate that the genotype of the embryos does not influence the development of teratomas. Displaced yolks sacs belonging to genetically sterile embryos developed into teratomas as frequently as those from heterozygotes and from genetically normal embryos.     

The effect of experimentally induced triploidy on the lethal expression of the t12 mutation in mouse embryos

Diploid embryos which are homozygous for the t¹² mutation die at the morula stage. In the current studies, ova from heterozygous ($\text{+}\text{t}{}^{12}$) females were fertilized in vitro with spermatozoa from $\text{+}\text{t}{}^{12}$ males. The fertilized ova were immediately placed into media containing cytochalasin B to prevent second polar body formation, producing +/+/+, +/+/t¹², +/t¹²/t¹², and t¹²/t¹²/t¹² embryos. The subsequent development of these triploid embryos was compared with that of diploid +/+, $\text{+}\text{t}{}^{12}$, and $\text{t}{}^{12}\text{t}{}^{12}$ embryos developing from ova which were also fertilized in vitro with spermatozoa from $\text{+}\text{t}{}^{12}$ males but which were not treated with cytochalasin B immediately following gamete coincubation. The data show that those triploid embryos which possess a wild-type allele and two mutant alleles are phenotypically wild type while those possessing three mutant alleles are not phenotypically distinguishable from their diploid ($\text{t}{}^{12}\text{t}{}^{12}$) counterparts. Like $\text{t}{}^{12}\text{t}{}^{12}$ embryos, t¹²/t¹²/t¹² embryos die at the morula stage, prior to blastocoelic cavity formation.     

Temperature dependence of active K+ transport in cation dimorphic sheep erythrocytes

Arrhenius diagrams of K⁺ pump fluxes measured between 15°C and 41°C were discontinuous in high K⁺ but not in low K⁺ sheep red cells. Exposure of low K⁺ cells to anti-L caused a bimodal temperature response of K⁺ pump flux with a transition temperature, $\text{T}\text{c}$, similar to that found in high K⁺ cells but with comparatively higher activation energies above $\text{T}\text{c}$.     

Comparative studies between microbiological culture and uptake of uridine/uracil to detect mycoplasmal infection of cell cultures.

Controlled, prospective studies were performed to compare detection of cell culture mycoplasmas by ratio of uptake of tritiated uridine (UdR) to tritiated uracil (U) and by microbiological culture. Culture was by standard agar and broth inoculation with aerobic and anaerobic incubation; immunofluorescent staining of indicator cell cultures was used to detect M. hyorhinis. The ratio of uptake of UdR to U ($\text{UdR}\text{U}$) and interpretation of test results were by standard published methods and performed in triplicate. 115 cell cultures were simultaneously assayed by the two techniques. 84 cultures (73.1%) yielded agreement between the 2 methods; 2 cultures (1.7%) yielded conflicting results, and 29 cultures (25.2%) yielded $\text{UdR}\text{U}$ results in the questionable range. Conflicting results consisted of two negative $\text{UdR}\text{U}$ tests in mouse cell cultures infected with M. orale. In separate studies, 3T-6 cultures freshly infected with M. orale yielded negative $\text{UdR}\text{U}$ results 3 days after infection, questionable results after 10 days and a positive $\text{UdR}\text{U}$ 17 days after infection. $\text{UdR}\text{U}$ detected infection in fibroblast, epithelial, and lymphocyte cell cultures. Highest $\text{UdR}\text{U}$ ratios were detected in human skin fibroblasts at early population doubling levels (PDLs), 4064 in one culture at PDL4. $\text{UdR}\text{U}$ was determined for IMR-90, a human diploid fibroblast at 12 different PDLs using the same lot of media. $\text{UdR}\text{U}$ gradually decreased throughout the life of the culture, from 2 125 at PDL6 to 340 at PDL36. Cultures in phase III and others exhibiting poor growth frequently yielded questionable or false-positive $\text{UdR}\text{U}$ results and were not included in tabulations of these results. $\text{UdR}\text{U}$ determined in endothelial cell cultures decreased as population density increased. In a representative experiment performed over a 4-day period, the $\text{UdR}\text{U}$ values were 1 808, 955 and 356 when the number of endothelial cells in culture were 5.3 × 10⁵, 6.6 × 10⁵ and 1.1 × 10⁶, respectively.     

Letter: Packing of microfibrils in collagen

X-ray diffraction data obtained from rat tail tendon can be indexed on a tetragonal unit cell with $\text{a = 2 × 38·47}\text{A}\text{?}$, $\text{c = 4 × 670}\text{A}\text{?}$, space group P4₁ or P4₃, in which all the intermicrofibril contacts are quasi-equivalent.     

Cell surface glycosyltransferase activities during normal and mutant (TT) mesenchyme migration

Migrating cells possess surface glycosyltransferase activity toward extracellular substrates, and the appearance of enzyme activity coincides with the onset of cellular migration (Shur, 1977a, Shur, 1977b, Develop. Biol.58, 23–39, 40–55; E. A. Turley and S. Roth, 1979, Cell17, 109–115). In this paper, surface glycosyltransferases were examined during normal and $\text{T}\text{T}$ mutant mesenchyme migration. Of six glycosyltransferases that were assayed, only galactosyltransferase was present at significant levels on the cell surface, despite the presence of a variety of intracellular glycosyltransferases. All controls have been performed to show clearly the enzyme activity was cell surface localized. In both normal and $\text{T}\text{T}$ embryos, surface galactosyltransferase activity was localized, by autoradiography, primarily to migrating mesenchymal cells, and to a lesser degree, to presumptive neural epithelium. During primitive streak formation, putative $\text{T}\text{T}$ embryos were devoid of surface galactosyltransferase activity. However, as development progressed, the $\text{T}\text{T}$ level of activity eventually exceeded wild-type levels by two- to sixfold and was evident in $\text{T}\text{T}$ tissues prior to the onset of microscopic pathology. Other surface enzymes assayed did not show any $\text{T}\text{T}\text{-}\text{dependent}$ increase in activity. The extracellular galactosyl acceptors were not chloroform:methanol soluble, and glycopeptides prepared by exhaustive Pronase digestion were excluded from Sephadex G-50. This large galactosylated glycoconjugate was readily digestable with endo-β-galactosidase, and, therefore, is similar to the poly-N-acetyllactosamine chains previously identified on early embryonic tissues (A. Kapadia, T. Feizi, and M. J. Evans, 1981, Exp. Cell. Res.131, 185–195; T. Muramatsu, G. Gachelin, M. Damonneville, C. Delarbre, and F. Jacob, 1979, Cell18, 183–191; A. Heifetz, W. J. Lennarz, B. Libbus, and Y. -C. Hsu, 1980, Develop. Biol.80, 398–408). These results support an involvement of surface galactosyltransferases in mesenchyme formation and during migration on poly-N-acetyllactosamine substrates.     

Kinetic parameters for the binding of p-nitrophenyl alpha-d-mannopyranoside to concanavalin A.

Binding of the chromogenic ligand p-nitrophenyl α-d-mannopyranoside to concanavalin A was studied in a stopped-flow spectrometer. Formation of the protein-ligand complex could be represented as a simple one-step process. No kinetic evidence could be obtained for a ligand-induced change in the conformation of concanavalin A, although the existence of such a conformational change was not excluded. The entire change in absorbance produced on ligand binding occurred in the monophasic process monitored in the stopped-flow spectrometer. The value of the apparent second-order rate constant (k_a) for complex formation (k_a = 54,000 s^?1m^? at 25 °C, pH 5.0, Γ/2 0.5) was independent of the protein concentration when the protein was in the range of 233–831 μm in combining sites and in excess of the ligand. The apparent first-order rate constant (k_?a) for dissociation of the complex was obtained from the rate constant for the decomposition of the complex upon the addition of excess methyl α-d-mannopyranoside (k_?a = 6.2 s^?1 at 25 °C, pH 5.0, Γ/2 0.5). The ratio $\text{k}{}_{\mathrm{<mtext>a</mtext>}}{}_{\mathrm{<mtext>?</mtext><mtext>a</mtext>}}$ (0.9 × 10₄m^?1) was in reasonable agreement with value of 1.1 ± 0.1 × 10⁴m^?1 determined for the equilibrium constant for complex formation by ultraviolet difference spectrometry. Plots of ln($\text{k}{}_{\mathrm{<mtext>a</mtext>}}\text{T}$) and ln($\text{k}{}_{\mathrm{<mtext>a</mtext>}}\text{T}$) vs $\text{1}\text{T}$ were linear (T is temperature) and were used to evaluate activation parameters. The enthalpies of activation for formation and dissociation of the complex are 9.5 ± 0.3 and 16.8 ± 0.2 kcal/mol, respectively. The unitary entropies of activation for formation and dissociation of the complex are 2.8 ± 1.1 and 1.3 ± 0.7 entropy units, respectively. These entropy changes are much less than those usually associated with substantial changes in the conformation of proteins.     

Evaluation of the water environments in deoxygenated sickle cells by longitudinal and transverse water proton relaxation rates

The longitudinal and transverse water proton relaxation rates of oxygenated and deoxygenated erythrocytes from both normal adults and individuals with sickle cell disease were measured as a function of temperature at two different frequencies. The simplest model which fits all of the data consists of three different environments for water molecules. The majority of the water (98%) has a correlation time indistinguishable from bulk water (3 × 10^?11 sec). Secondly, there is a small amount of water (1.3–1.5%) present which has a correlation time of 2–4 × 10 ^?9 sec and is apparently independent of the erythrocyte sample studied. Presumably this water is the hydration sphere around the hemoglobin molecules and its correlation time is significantly slower than bulk water. The third environment contains approximately 0.2% of the water present and has a correlation time≥ 10^?7 sec. This third environment is considered tightly bound to the hemoglobin because the water proton correlation time is very similar to the expected rotational correlation time for the hemoglobin molecules. The value of the transverse relaxation rate, f_b(T_2b)^?1, for the tightly bound water fraction decreases in oxy ($\text{S}\text{S}$), deoxy ($\text{A}\text{A}$), and oxy ($\text{A}\text{A}$) erythrocyte samples as the temperature is increased as expected for a rotational correlation time process. In dramatic contrast,f_b (T_2b)^?1 increases almost linearly as the temperature is increased over the whole 4 ° to 37 °C temperature range in samples of deoxy ($\text{S}\text{S}$) erythrocytes. The observation suggests a continual increase in the formation of deoxyhemoglobulin S polymers rather than a sudden transition from a homogeneous solution of deoxyhemoglobin S molecules to a solid gel.     

Trypanosoma lewisi: alterations in membrane function in the rat.

DEAE-cellulose-purified Trypanosoma lewisi from 4-day (dividing trypanosomes) and 7-day (non-dividing trypanosomes) infections in rats were compared for initial uptake of glucose, leucine, and potassium. Glucose entered the parasitic cells by mediated (saturable) processes, whereas leucine and K⁺ entered by mediated processes and diffusion. Glucose entry was significantly elevated in 4-day cells (V_max 4.00 ± 1.02 nmoles/ 1 × 10⁸ cells/min) with respect to 7-day cells (V_max 1.83 ± 0.62 nmoles 1 × 10⁸ cells/min). Likewise, the affinity of the glucose carrier was significantly greater in 4-day cells (K_m = 0.30 ± 0.02 mM) than in 7-day cells (K_m = 0.59 ± 0.11 mM). When leucine and K⁺ transport were compared in 4- and 7-day populations, significant elevations in the rate of entry (V_max) of both substrates were observed for 4-day cells; K_m values for leucine and K⁺ were not altered by the stage of infection. For leucine, the V_max and K_m for 4-day cells were 2.40 ± 0.50 nmoles/1 × 10⁸ cells/30 sec and 78 ± 7 μM, respectively; corresponding values in 7-day cells were 1.06 ± 0.02 nmoles/1 × 10⁸ cells/30 sec and 66 ± 11 μM. For K⁺, the V_max and K_m for 4-day cells were 15.97 ± 0.38 nmoles/1 × 10⁸ cells/min and 1.2 mM, respectively; corresponding values in 7-day cells were 4.76 ± 1.82 nmoles/1 × 10⁸ cells/min and 1.05 mM. The observed increase in the rate of K⁺ entry into 4-day cells was attributable to enhanced influx; no significant difference in the rate of K⁺ efflux was noted when 4- and 7-day cells were compared ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of K⁺ leak for 4- and 7-day cells were 68.1 ± 9.3 and 67.9 ± 15.2 min, respectively). Potassium influx was ouabain insensitive. Membrane function in 7-day cells was not uniformly inhibited. No significant difference in the activity of the membrane-bound enzyme, 5′-nucleotidase, was observed when 4- and 7-day cells were compared.     

Thermoelectric (seebeck) effect of the cuticle of social wasps

The thermoelectric (Seebeck) coefficient ($\text{S =}\text{ΔV}\text{ΔT}$) in various cuticular areas of the Oriental hornet (Vespa orientalis) fluctuates from 0·3 to 2·4 mV deg^?1 within a temperature range of 27–36°C and when the temperature difference between the two measuring electrodes (ΔT) is 0·6–8·0°C. The values measured on the brown-colored cuticle suggest an n-type conduction, while those measured on the yellow-colored cuticle point to a p-type conduction. It is suggested hornets use this phenomenon for temperature detection.     

Fertility of ram semen after storage at 5°C

In five experiments, fertilization, early (18–19-day) pregnancy, and lambing were examined after insemination with semen stored at 5°C in tris-fructose-egg yolk diluent.After deposition into uterine horns by surgical insemination of semen stored for 0 (control), 2, 4, 6, 8, 9 or 10 days, fertilized eggs were recovered in $\text{32}\text{34}\text{,}\text{16}\text{16}\text{,}\text{21}\text{22}\text{,}\text{15}\text{20}$, $\text{9}\text{17}\text{,}\text{2}\text{18}$ and $\text{1}\text{15}$ ewes; the 18–19-day pregnancy rates determined by progesterone assay were $\text{32}\text{48}\text{,}\text{15}\text{28}\text{,}\text{11}\text{20}\text{,}\text{12}\text{20}\text{,}\text{9}\text{20}$, $\text{2}\text{20}$ and $\text{1}\text{21}$ for the respective storage periods. There was a linear decrease in fertilization rates beyond 4 days of storage and in early pregnancy rates after 6 days of storage (P<0.001). The decline with time of storage in the fertilization rate was not associated with an increase in early embryonic loss. Surgical insemination with semen stored for 0, 4, 6, 8, 9 and 10 days resulted in 53, 35, 40, 25, 5, and 0% lambing.Single cervical (normal) insemination of a total of 281 ewes with 0, 1, 2 or 3-day-old semen, using within each semen treatment 90 × 10⁶ and 180 × 10⁶ spermatozoa, yielded mean lambing rates of 60.0, 34.3, 33.8, and 17.1%; and after using 150 × 10⁶ and 300 × 10⁶ spermatozoa in a total of 393 ewes the mean lambing rates for the above semen treatments were 69.0, 46.4, 36.1, and 24.2% (linear, P < 0.001). In both tests the lambing results were better after insemination of the higher number of spermatozoa, but the slope of decline in fertility with age of semen was not affected by the sperm dose.When single and double cervical inseminations were performed in a total of 411 ewes, with 150 × 10⁶ and 300 × 10⁶ spermatozoa per inseminate, the lambing rates for semen stored for 0, 1, 2 and 3 days were 57.7, 30.4, 26.8, and 4.7% after single insemination, and 66.7, 56.8, 46.4, and 41.5% after double inseminations. The sperm dose within method of insemination and semen treatment had no effect. The lambing rate was better after double than single insemination (P<0.001), but the slope of decline in fertility with age of semen was not significantly affected by number of inseminations.In the final experiment, involving 408 ewes, 300 μg of prostaglandin F₂α added to the inseminate did not improve the fertility of fresh semen or semen stored for 1 day.