A Close Relationship between Increases in Galactosyltransferase Activity and the Accumulation of Galactolipids during Plastid Development in Cucumber Seedlings

Changes in the activity of UDP-galactose:diacylglycerol galactosyltransferase(UDGT), a key enzyme in galactolipid biosynthesis, during germinationwere investigated in cucumber (Cucumis sativus L. cv. Aonagajibai)seedlings. After germination, UDGT activity increased duringgrowth in darkness for 4 days, reaching 10 times the activityin ungerminated seeds. Illumination of 4-day-old dark-grownseedlings strongly stimulated the activity. By contrast, inseedlings grown continuously in darkness, the increase in UDGTactivity ceased after 4 days and the activity remained constantthereafter. A similar increase in the specific activity of UDGTwas observed i n the envelope fraction from seedlings, indicatingthat the increase in the enzymatic activity preceded synthesisof other proteins in the envelope membrane. Coincident withthe change in the enzymatic activity, here was an increase inlevels of monogalactosyl diacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), two major constituents of chloroplastmembrane lipids, in the germinated seedlings. Cycloheximideinhibited the light-mediated increase in the enzymatic activityby illumination of 4-day-old dark-grown seedlings, and, as aconsequence, it inhibited the accumulation of MGDG and DGDG.It was clear, therefore, that protein synthesis was necessaryduring this activation. Addition of a cytokinin, benzyladenine(BA), stimulated the increase in the UDGT activity. The increasein the UDGT activity caused by BA was accompanied by the accumulationof galactolipids, as in the case of the activation by light.These results suggest that activation of the final reactionin the synthesis of MGDG, which is catalyzed by the galactosyl-transferase,contributes to the accumulation of galactolipids during thedevelopment of the chloroplast membrane. (Received December 3, 1994; Accepted July 3, 1995)     

Plasmodium lophurae: Antibody-induced movement and capping of surface membranes of erythrocyte-free malarial parasites

Surface antigens of the avian malarial parasite, Plasmodium lophurae, and its host cell, the duckling erythrocyte, were visualized at the ultrastructural level using rabbit antisera and ferritin-labeled goat anti-rabbit IgG. Rabbit antisera to P. lophurae caused an aggregation of parasite and parasitophorous vacuole surface membrane antigens, a phenomenon known as capping. Capping required living plasmodia and did not occur if parasites had been fixed with glutaraldehyde prior to exposure to antisera. Antisera against duckling erythrocytes did not cross-react with erythrocyte-free malarial parasites, and did not form caps on the surface of the red blood cell. Antiplasmodial sera did not react with normal or malaria-infected red cells. These results suggest that surface membrane proteins of the intracellular plasmodium are capable of lateral movement.     

Effect of hypo-osmotic environmental changes on the expression of gonadotropin-releasing hormone,its receptor,and gonadotropin hormone subunit mRNA in adult chum salmon (Oncorhynchus keta)

Migrating fish such as salmonids are affected by external environmental factors and salinity changes are particularly important, influencing spawning migration. The aim of this study was to test whether changes in salinity would affect the expression of the hypothalamic-pituitary-gonadal (HPG) axis hormones (gonadotropin-releasing hormones (GnRHs) [salmon GnRH and chicken GnRH-II], GnRH receptors [GnRHR1 and GnRHR5], and mRNA of the gonadotropin hormone [GTH] subunits [GTHα, follicle stimulating hormone β, and luteinizing hormone β]) in chum salmon (Oncorhynchus keta). Fish were progressively transferred from seawater (SW) through 50% SW to freshwater (FW), and the relationship between the osmoregulatory hormone prolactin (PRL) and sexual maturation was determined. The expression and activity of HPG hormones and their receptors, and levels of estradiol-17β and PRL increased after fish were transferred to FW, demonstrating that changes in salinity stimulate the HPG axis and PRL production in migrating chum salmon. These findings reveal details about the role of the endocrine system in maintaining homeostasis and stimulating sexual maturation and reproduction in response to salinity changes in this species.     

Interactions between climatic and production factors on returns of female pigs to service during summer in Japanese commercial breeding herds

The objectives of this study were to determine the associations between climatic factors and production factors for returns to service of female pigs during summer and to quantify the associations between these factors and occurrences of returns to service. The factors that were assessed were as follows: maximum temperature (HT), relative humidity, age of gilts at first mating, parity, weaning-to-first-mating interval (WMI), and lactation length. The study analyzed records of 18,307 gilts in 99 herds and 78,135 parity records of 56,322 sows in 103 herds; all the females were first-serviced between June and September, 2007 to 2009. Average daily HT and relative humidity for 15 days post-service of a female were obtained from 21 local weather stations and coordinated with the performance data of the respective local herds. The returns to service were categorized into three groups: regular returns (RRs: 18–24 days), irregular returns (IRs: 25–38 days), and late returns to service (LRs: 39 days or later). Two-level mixed-effects models were applied to the data by using a herd at level 2 and an individual record at level 1. In mated gilts, the occurrences (%) of RRs, IRs, and LRs were 4.8%, 1.8%, and 5.3%, respectively. In mated sows, the respective occurrences were 3.3%, 1.8%, and 4.2%. Mean values (ranges) of HT and relative humidity were 28.4 °C (13.6 °C–39.8 °C) and 73.4% (35.0%–98.0%), respectively. In gilts, as HT increased from 25 °C to 30 °C, the occurrence of RR increased from 3.7% to 4.4% (P < 0.05). However, there was no association between the occurrence of RR and either relative humidity (P = 0.17) or age at first mating (P = 0.23). In addition, there were no associations between the occurrences of either gilt IR or LR and HT (P ≥ 0.05), relative humidity (P ≥ 0.46), or age at first mating (P ≥ 0.32). In sows, greater occurrences of RRs, IRs, and LRs were associated with higher HT, lower parity, and a WMI of 7 days or longer (P < 0.05), but they were not associated with relative humidity (P ≥ 0.62) or lactation length (P ≥ 0.13). The occurrence of RRs in sows of all WMI groups increased 1.22 (1.04⁵) times for each 5 °C increase in HT. For sows with WMI 0 to 6 days, each 5 °C rise in HT increased the occurrence of IRs and LRs by 1.36 (1.06⁵) and 1.27 (1.05⁵) times, respectively. However, there was no association between increased HT and occurrences of IRs or LRs for sows with WMI 7 days or longer (P ≥ 0.38). Therefore, in order to prevent returns to service, it is recommended that producers apply cooling management for females during the post-service periods in summer.     

An NAD(P)H Model Reaction: Reduction of α-Keto Esters by the Hantzsch Ester Accelerated by Zinc Complex in the Reformatsky Mixture

Aiming to get useful steroidal alkaloids by tissue culture of Solanum laciniatum Ait., indefinitely growing callus tissue was prepared from the mother plant. Some nutritional requirements for the growth of the callus tissue were studied. By examining steroidal compounds in callus culture, cholesterol, stigmasterol, β-sitosterol, lanosterol, squalene, diosgenin and a new steroidal alkaloid were found to be formed in the callus culture. The new steroidal alkaloid was found to be solasodine derivative containing rhamnose and other unidentified sugars.     

A New Natural Quinone, 2-Methyl-3-II,III,VIII,IX-octahydromultiprenyl9-1,4-naphthoquinone Isolated from Streptomyces albus

Purification of the precipitates obtained from the juice oil of Citrus hassaku by chromatography afforded 7-geranyloxycoumarin (aurapten) and two compounds (mp 43~45°C and 122~124°C), whose structures were determined to be epoxyaurapten and marmin on the basis of spectral evidence. These compounds were isolated from Citrus hassaku for the first time. The spasmolytic activity was tested of aurapten, epoxyaurapten, marmin and their related compounds, which were synthesized from aurapten and marmin, on the small intestine removed from a male guinea pig. Epoxyaurapten exhibited the highest activity among them against the small intestine’s contraction induced by BaCl₂.     

Purification,Properties and Recognition Sequence of Site-specific Restriction Endonuclease from Acetobacter liquefaciens AJ 2881

A type II restriction endonuclease, designated as AliAJI, was purified from cells of Acetobacter liquefaciens AJ 2881 by combined column chromatography on heparin-Sepharose CL-6B, DEAE-Sepharose CL-6B and blue Sepharose CL-6B. The purified enzyme was homogeneous on polyacrylamide gel disc electrophoresis, and the enzyme preparation was free from other nuclease activities, as judged by constancy of lambda DNA-digest electrophoretic patterns after prolonged incubation for 24 hr. The enzyme was optimally active at 37°C at pH 7.5, required neither sodium chloride nor ammonium sulfate, both of which rather inhibited enzyme activity at high concentration (100 and 75 mM, respectively), and cleaved lambda, φX174 RF, SV40, pBR322, M13 mp7 RF and Ad2 DNAs at 18, 1,2, 1, 1 and 25 or more sites, respectively. The recognition sequence of the enzyme on DNA molecules was determined to be 5′-C-T-G-C-A-G-3′, and the enzyme was found to cut between A and G in the sequence, being an isoschizomer of the endonuclease of Providencia stuartii 164 (PstI).