Analysis of the nuclear envelope polypeptides by isoelectric focusing and electrophoresis

The more insoluble polypeptides of the avian erythrocyte nuclear envelope have been characterized by a two-dimensional electrophoretic procedure. Most of the polypeptides occur in two classes with isoelectric points of approximately 6.4 and 5.7 respectively. The more acidic class contains two polypeptides, P71 and one which contributes to an electrophoretic band previously identified as P55. The more basic class includes P75, P68, P61 and two or more polypeptides from the P55 band. There are four to six isoelectric point variants of each polypeptide in the more basic class, and the relative stain intensities for the variants are similar for the different polypeptides. These similarities in ionic properties suggest a chemical relationship between the polypeptides. These results are discussed in relation to the in vitro conversion of P75 to polypeptides of the same molecular weight as P68, P61 and P55.     

Osmotic and cryoprotective effects of glycerol-sucrose solutions on day-3 mouse embryos

The relative volume of Day-3 mouse embryos changed as a linear function of the reciprocal of osmolality [corrected] of non-permeating solutes after 10 min exposure to sucrose and glycerol-sucrose solutions at 20 degrees C. The slope of the linear regression line was less in glycerol-sucrose than in sucrose solutions because glycerol permeation caused re-expansion. Before freezing by direct transfer to -180 degrees C the embryos were placed into glycerol-sucrose in 1-step (1-step equilibration) or first into glycerol and then into glycerol-sucrose (2-step equilibration). Using 2-step equilibration the post-thaw survival rate was substantially higher at 3.0 and 4.0 M-glycerol levels and less dependent on changes in the sucrose concentration within the range of 0.125 to 1.0 M than with 1-step equilibration. Under optimal conditions 90-95% of rapidly frozen embryos developed to blastocysts in vitro and 30% into live young in vivo. It is suggested that the cryoprotective role of glycerol is due to its ability to reduce osmotic pressure differences between the extra and intracellular spaces during rapid freezing of embryos.     

Osmotic characteristics of sheep and cattle embryos

Ten minutes of exposure to increasing concentrations of sucrose caused a proportional decrease in the volume of sheep late morulae, their relative volume changed as a linear function of the reciprocal of the osmolality of the medium. Day 6 sheep and Day 7 cattle embryos responded to the addition of permeating cryoprotectants by an initial shrinkage which was followed by gradual reexpansion. After 1.25 min exposure the relative volumes of sheep and cattle embryos respectively were 20 and 25% smaller in glycerol than in ethylene glycol. The volumes of cattle and sheep embryos remained smaller in glycerol than in ethylene glycol up to the final observation at 30 min. The osmotic response of sheep late morulae to 2.0 M propylene glycol was intermediate between their response to 2.0 M glycerol and to 2.0 M ethylene glycol. These results indicate that Day 6 sheep and Day 7 cattle embryos are more permeable to ethylene glycol than to glycerol.     

Value of a control decision rule for leek moth infestations in leek

Fourteen commercial leek fields with first and second generation Leek moth, Acrolepiopsis assectella Z., (LM) injury were sampled during 1986 in The Netherlands. For both generations, plant injury was more prevalent in the perimeter of the field than in interior portions. A sequential sampling program for use in making treatment decisions for LM was developed. An economic analysis of the value of sampling information derived from the sequential sampling program was performed. The parameters used for the analysis were crop yield and value, expected level of LM infestation, potential loss of value due to LM infestation, effectiveness of insecticide application, and cost of sampling. Due mainly to the high value of the crop and low cost of treatment, analysis indicates that there is little difference between a sampling-based management plan and prophylactic application of insecticides in terms of pest control costs. Additionally, such a sampling-based management plan is relatively insensitive to changes in the parameters used in the model. Thus, development of a threshold linked to a sampling procedure will not reduce pest control costs. Use of the sampling-based management plan will also not significantly increase pest control costs and will likely result in reduced insecticide use compared with a prophylactic treatment program.

---

Zusammenfassung In den Niederlanden wurde 1986 der durch den Befall der ersten und zweiten Generation der Lauchmotte (Acrolepiosis assectella Z.) verursachte Schaden auf 14 kommerziell genutzten Porreefeldern ermittelt. Für beide Generationen wurde an den Feldrändern ein deutlich höherer Befall als in dem inneren Bereich eines Feldes festgestellt. Zur Bekämpfung der Lauchmotte wurde als Entscheidungsmodell ein sequentielles Probenahmeverfahren entwickelt. Der Informationsgehalt der sequentiellen Befallserhebung wurde einer ökonomischen Bewertung unterzogen. Hierbei wurden folgende Parameter zugrunde gelegt: Erntemenge und Ertrag, erwarteter Befallsgrad sowie hierdurch verursachter möglicher Ertragsverlust, Wirkungsgrad einer Insektizidbehandlung und Kosten der Stichprobennahme. Die Analyse der einzelnen Parameter ergab nur eine geringe Kostendifferenz zwischen einer gezielten Bekämpfung nach sequentieller Probenahme und prophylaktischen Insektizidspritzungen, bedingt durch den hohen Wert der Kultur und die niedrigen Kosten einer Bekämpfung. Darüber hinaus its das Verfahren einer gezielten Lauchmottenbekämpfung gegeüber Veränderungen der obengenannten Parameter relativ unempfindlich. Deshalb wird die Entwicklung eines Schwellenwertes der mit Probenahmeverfahren verbunden ist die Bekämpfungskosten nicht reduzieren. Die anwendung der Probenahmeplans würde Bekämpfungskosten auch nicht erhöhen und würde wahrscheinlich Insecktizidverbrauch reduzieren im Vergleich zu einen prophylaktischen Behandlungsprogramm.

     

Soluble derivatives of the beta amyloid protein precursor of Alzheimer's disease are labeled by antisera to the beta amyloid protein

The amyloid deposited in Alzheimer's disease (AD) is composed primarily of a 39-42 residue polypeptide (beta AP) that is derived from a larger beta amyloid protein precursor (beta APP). In previous studies, we and others identified full-length, membrane-associated forms of the beta APP and showed that these forms are processed into soluble derivatives that lack the carboxyl-terminus of the full-length forms. In this report, we demonstrate that the soluble approximately 125 and approximately 105 kDa forms of the beta APP found in human cerebrospinal fluid are specifically labeled by several different antisera to the beta AP. This finding indicates that both soluble derivatives contain all or part of the beta AP sequence, and it suggests that one or both of these forms may be the immediate precursor of the amyloid deposited in AD.     

Survival of sheep demi-embryos in vivo and in vitro

Sheep embryos (morulae and blastocysts) were bisected either by microscalpel or by microneedle after dissolving the zona pellucida with acidified Tyrode's solution. Fourteen and 11 cryopreserved demi-embryos failed to develop when transferred to recipients or placed in culture, respectively. When fresh demi-embryos were cultured in Dulbecco's phosphate buffered saline (DPBS) plus fetal calf serum (FCS) or Whitten's medium, the survival rate was 26% compared to 68% for whole embryos (P<0.01), and there was a suggestion that the presence of a zona pellucida was beneficial to survival. When two demi-embryos each within a zona pellucida were transferred into each of 10 ewes, six of them lambed to produce a total of eight lambs, including two sets of identical twins. Of 10 ewes receiving two demi-embryos without zonae pellucidae, three lambed to produce a total of four lambs, including one set of identical twins. Of 10 ewes that each received two whole embryos, 10 lambed to produce a total of 16 lambs. There was a suggestion that the zona pellucida might enhance the survival of demi-morulae but not demi-blastocysts.     

Forms and intracellular distribution of alpha-D-mannosidases in murine liver and spleen

1. The intracellular distribution of alpha-D-mannosidase in homogenates of murine liver and spleen was investigated by differential and gradient density centrifugation. 2. In both tissues an enzyme with a neutral pH optimum was found in the cytosol together with an alpha-D-mannosidase with optimal activity between pH 5.5 and 6.0 which was also partially membrane-bound. 3. In liver the acidic alpha-D-mannosidase was obtained almost entirely in a particulate form distributed equally between a heterogeneous low density region and heavy density lysosomes. 4. The lysosomal form of the liver enzyme was purified to electrophoretic homogeneity and shown to be a glycoprotein composed of four identical subunits of molecular weight 65 kDa. 5. Antibody raised against the purified liver alpha-D-mannosidase immunoprecipitated a polypeptide from spleen which had the same molecular size. This acidic enzyme was the predominant type of alpha-D-mannosidase in spleen, but in contrast to liver, it was obtained mainly in a cytosoluble form, the remaining activity being present in the heterogeneous light density compartment. 6. Although both tissues contain the same molecular form of the acidic alpha-D-mannosidase, in murine spleen this enzyme does not appear to be associated with stable heavy density lysosomes.     

Local reproductive tract immunity to sperm-specific lactate dehydrogenase-C4

Immunity to sperm-specific lactate dehydrogenase C4 (LDH-C4) results in reduction of fertility in females. Stimulation of a local mucosal immune response to LDH-C4 in the reproductive tract would guarantee the presence of antibodies at the site of fertilization, which should enhance suppression of fertility. After intrauterine immunization with LDH-C4, SJL/J female mice secrete immunoglobulin (Ig)A antibodies specific for LDH-C4 into their uterine fluids. Furthermore, these animals demonstrate a lower pregnancy rate than controls receiving an intrauterine immunization without LDH-C4. Thus, induction of a local immune response is an effective alternative to systemic immunization for administering a contraceptive vaccine.     

Interactions between WHITE Genes Carried by a Large Transposing Element and the ZESTE Allele in DROSOPHILA MELANOGASTER

TE146, a large transposing element of Drosophila melanogaster, carries two copies of the white and roughest genes in tandem. In consequence, z¹ w ^11E4; TE146(Z)/+ flies have a zeste (lemon-yellow) eye color. However, one in 10³ TE146 chromosomes mutates to a red-eyed form. The majority of these "spontaneous red" (SR) derivatives of TE146 have only one copy of the white gene and are, cytologically, two- to three-banded elements, rather than six-banded as their progenitor. The SR forms of TE146 are also unstable and give zeste-colored forms with a frequency of about one in 10⁴. One such "spontaneous zeste" (SZ) derivative carries duplicated white genes as an inverted, rather than a tandem, repeat. The genetic instability of this inverted repeat form of TE146 is different from that of the original tandem repeat form. In particular, the inverted repeat form frequently produces derivatives with internal rearrangements of the TE and gives a much lower frequency of SR forms. In addition, two novel features of the interaction between w⁺ alleles in a zeste background have been found. First, copies of w ⁺ can become insensitive to suppression by zeste even when paired. Second, an inversion breakpoint may disrupt the pairing between two adjacent w⁺ alleles, necessary for their suppression by zeste, without physically separating them.     

Sucrose dilution of glycerol from mouse embryos frozen rapidly in liquid nitrogen vapour

The toxic effects of sucrose and the conditions of in-straw glycerol removal after freezing and thawing were studied using Day-3 mouse embryos. At 20 degrees C, exposure to less than or equal to 1.0 M-sucrose for periods up to 30 min had no adverse effects on freshly collected embryos. At 25 and 36 degrees C, however, greater than or equal to 1.0 M-sucrose significantly reduced the developmental potential (P less than 0.001). In the freezing experiments the embryos were placed in 0.5 ml straws containing 40 microliters freezing medium separated by an air bubble from 440 microliters sucrose solution. The straws were frozen rapidly in the vapour about 1 cm above the surface of liquid nitrogen. The post-thaw viability was substantially better after sucrose dilution at 20 degrees C than at 36 degrees C. Mixing the freezing medium with the sucrose diluent immediately after thawing further improved the rate of survival relative to mixing just before freezing (P less than 0.001). The best survival was obtained when the freezing medium contained 3.0 M-glycerol + 0.25 M-sucrose; it was mixed with the diluent after thawing and the glycerol was removed at 20 degrees C. Under such conditions the sucrose concentration in the diluent had no significant effect on the rate of development (0.5 M, 69%; 1.0 M, 73%; 1.5 M, 64%). The results show that during sucrose dilution the temperature should be strictly controlled and suggest that intracellular and extracellular concentrations of glycerol are important in the cryoprotection of embryos.