Isolation and characterisation of a non-polyadenylated mRNA species with an affinity for poly(adenylic acid) from Friend leukaemia cells

Utilizing the technique of poly(A)-Sepharose affinity chromatography, it is possible to isolate a novel class of RNA molecules from polysomes of Friend leukaemia cells. These RNA species display messenger RNA-like behaviour. They are released from polysomes on treatment with EDTA and are able to direct polypeptide synthesis in a cell-free protein synthesising system. They appear to be distinct from the polyadenylated mRNAs, as judged by their lack of a 3'-terminal poly(A) tract, by their different size distribution, by their unusual base composition, by the presence of a possible 'uridylate rich' region towards their 3'-end, by their low sequence homology to polyadenylated mRNAs and by the difference in at least some of their translation products.     

Slow reacting substance of anaphylaxis, SRS-A: Assignment of the stereochemistry

We have recently described the structure elucidation of slow reacting substance of anaphylaxis (SRS-A) from lung and of a slow reacting substance (SRS) from basophilic leukaemia cells as 5-hydroxy-6-cysteinylglycinyl-7,9,11,14-eicosatetraenoic acid. The stereochemistry of this molecule has now been shown to be 5(S)-hydroxy-6(R)-cysteinylglycinyl-7,9-trans-11,14-cis-eicosatetraenoic acid by comparison of the synthetic and natural products and their derivatives using mass spectrometric and HPLC chromatographic techniques. The synthetic and natural compounds are also indistinguishable by their pharmacological properties, their conversion by soybean lipoxygenase, and their UV spectra.     

A technique for isolating pure, viable parenchymal cells and their nuclei from rat mammary gland

Parenchymal cell preparations of high purity and of sufficient yield for biochemical studies were obtained by treatment of rat mammary gland tissue with a curde preparation of collagenase and trypsin in tissue culture medium 199, followed by filtration. The isolated cells, obtained in approximately 2 hr, were of acceptable quality as determined by (a) their appearance in the light microscope, (b) their ability to exclude trypan blue, and (c) their ability to incorporate [³H]lysine into cellular protein in vitro. A method is also described for purifying parenchymal cell nuclei in high yield by ultracentrifugation in dense sucrose. The isolated nuclei were of acceptable quality as judged by (a) their appearance in the light microscope and (b) their RNA, DNA, and protein content.     

The absence of direct relationship between the ability of yeasts to grow at elevated temperatures and their survival after lethal heat shock

The study of the growth of the yeasts Rhodotorula rubra, Saccharomyces cerevisiae, and Debaryomyces vanriji at elevated temperatures and their survival after transient lethal heat shock showed that the ability of these yeasts to grow at supraoptimal temperatures (i.e., their thermoresistance) and their ability to tolerate lethal heat shocks (i.e., their thermotolerance) are determined by different mechanisms. The thermotolerance of the yeasts is suggested to be mainly determined by the division rate of cells before their exposure to heat shock.     

Dog's gaze at its owner increases owner's urinary oxytocin during social interaction

Oxytocin (OT) has been shown to play an important role in social bonding in animals. However, it is unclear whether OT is related to inter-species social bonding. In this study, to examine the possibility that urinary OT concentrations of owners were increased by their “dog's gaze”, perhaps representing social attachment to their owners, we measured urinary OT concentrations of owners before and after interaction with their dogs. Dog owners interacted with their dogs as usual for 30 min (interaction experiment) or were instructed not to look at their dogs directly (control experiment). We observed the behaviors of owners and their dogs during the experiments, and measured OT concentrations by radioimmunoassay in urine samples from the owners collected just before and 20 min after interaction with their dogs. Using a cluster analysis, owners could be divided into two groups: one received a longer duration of gaze from their dogs and reported a higher degree of relationship with their dogs (LG); the other received a shorter duration of gaze and reported a lower degree of relationship (SG). Urinary OT was higher in LG than SG after usual interaction with their dogs, but not in the control experiment. In the interaction experiment, a high correlation was found in LG between the frequency of behavioral exchanges initiated by the dog's gaze and the increase in urinary OT. We conclude that interactions with dogs, especially those initiated by the dog's gaze, can increase the urinary OT concentrations of their owners as a manifestation of attachment behavior.     

Sleep duration in hornets is influenced by physical and chemical means

Hornet workers (Vespa orientalis, Hymenoptera, Vespinae) were anesthetized by diethyl-ether, and their sleeping period was monitored. Sleep duration in hornets was found to be influenced by preexposure to horizontal rotation or to hypo- and hypergravity, by volatile fractions of their own venom and by the size of their habitat (crowding effect).     

Food partitioning between breeding White-tailed Kites (Elanus leucurus; Aves; Accipitridae) and Barn Owls (Tyto alba; Aves; Tytonidae) in southern Brazil.

I examined the diet of breeding White-tailed Kites (Elanus leucurus; Aves; Accipitridae) and Barn Owls (Tyto alba; Aves; Tytonidae) in an agrarian area of southern Brazil by analyzing regurgitated prey remains. The objective was to evaluate how these raptors, which differ markedly in their hunting activity periods (owls are nocturnal and kites diurnal), share their mammalian food component. 2,087 prey consumed by Barn Owls and 1,276 by White-tailed Kites were identified. They presented a high overlap of food-niches (Piankas index was 0.98). Based on the daily activity period of their main small mammal prey, a lower overlap would be expected. The crepuscular/nocturnal Mus musculus was the main prey for the diet of breeding Barn Owls (81%) and White-tailed Kites (63%). This small exotic rodent provided 63% of the small mammal biomass ingested by owls and 44% by kites. Larger native small mammals were also considered important for the diet of kites, mainly because of their biomass contribution. Although these raptors differ markedly in their hunting activity periods, Barn Owls and White-tailed Kites are very similar predators in southern Brazil, overlapping their diets.     

LeX/ssea-1 is expressed by adult mouse CNS stem cells,identifying them as nonependymal

Adult neural stem cells are rare, and little is known about their unique characteristics, leaving their in vivo identity enigmatic. We show that Lewis X (LeX), a carbohydrate expressed by embryonic pluripotent stem cells, is made by adult mouse subventricular zone (SVZ) stem cells and shed into their environment. Only 4% of acutely isolated SVZ cells are LeX(+); this subpopulation, purified by FACS, contains the SVZ stem cells. Ependymal cells are LeX(-), and purified ependymal cells do not make neurospheres, resolving the controversial claim that these are stem cells. Thus, LeX expression by adult CNS stem cells aids their in vivo identification, allows their enrichment, and raises new questions about the role of this unusual carbohydrate in stem cell biology.     

Prevention of unnecessary pregnancy terminations by counselling women on drug, chemical, and radiation exposure during the first trimester

As part of a new approach to counselling pregnant women concerned about antenatal exposure to drugs, chemicals, or radiation, we measured their tendency to terminate their pregnancy by using a visual analogue scale (VAS). Analysis of 78 cases where women had less than 50% tendency to continue pregnancy before they were advised by us reveals that 61 decided to continue their pregnancy after the consultation (57 normal, healthy infants, four miscarriages) and 17 terminated. Women who continued their pregnancy significantly changed their tendency after we discussed relevant information with them (from 34.3 +/- 2.5% to 84.5 +/- 3.3%, P less than 0.00001), whereas most of those who eventually terminated pregnancy did not change their tendency to continue pregnancy beyond the 50% mark (from 24.8 +/- 5.4% to 45.1 +/- 9.8%) (P greater than 0.1). Only two of the women who terminated their pregnancy were exposed to teratogenic drugs; however, in most other cases, other obvious reasons, unrelated to the exposure in question, were identified by the women as leading reasons for termination. An appropriate intervention in early pregnancy can prevent unnecessary pregnancy terminations by correcting misinformation and thereby decreasing the unrealistically high perception of risk by women exposed to nonteratogens.     

Bisphosphonates and bone resorption: effects on collagenase and lysosomal enzyme excretion

When added to cultures of parathyroid hormone (PTH)- bones, dichloromethylenebisphosphonate (C12MBP) and 3-amino-1-hydroxypropydilene-1,1-bisphosphonate (AHPrBP) inhibit completely and in a parallel manner the development of resorption lacunae, the loss of calcium by the explants and their PTH-induced excretion of lysosomal hydrolases (β-glucuronidase and N-acetyl-β-glucosaminidase). The loss of collagen (hydroxyproline) by the bones is usually less inhibited than their loss of calcium and their heparin-induced excretion of collagenase is unaffected. To interpret these data, it is proposed that these bisphosphonates act more on the activity of osteoclasts, suppressing simultaneously their excretion of lysosomal enzymes and their erosion of mineralized bone matrix, than on that of other cell types (osteoblasts ?) responsible for collagenase production and the removal of uncalcified collagen.     

Immune responses are required to terminate viremia in equine infectious anemia lentivirus infection.

Six normal and four immunodeficient horses were injected with a cloned variant of equine infectious anemia virus (EIAV). The six normal horses had detectable EIAV in their plasma by 7 days postinjection. During their primary viremic episode, which was accompanied by fever and anemia, maximum titers of EIAV in plasma ranged from 10(3.8) to 10(4.8) 50% tissue culture infective doses per ml. All six normal horses cleared detectable virus from their plasma by 21 to 35 days after injection. Horses with combined immunodeficiency became viremic by 9 days postinjection and also developed anemia. In contrast to normal horses, foals with combined immunodeficiency did not eliminate the virus from their plasma.     

Prototheca stagnora, an encapsulated organism

The type species of Prototheca stagnora, SEC-L-1690 (ATCC 16528) (2) was found to have a large capsule surrounding the cells, in India ink preparations. Cryptococcus neoformans and P. stagnora are very similar organisms in their morphology and they should be differentiated by their reproduction process or by their biochemical and physiological characteristics.     

Pathogen-induced plant proteins

Pathogen-induced plant proteins are classified by their functional characteristics: (a) involvement in plant cell signaling; (b) inhibition of enzymes excreted by the pathogens; (c) stabilization of plant cell walls or ability to trigger apoptosis; (d) enzymatic activity producing lysis of cell walls of pathogenic fungi and bacteria; (e) enzymatic activity in metabolic pathways of phenylpropane and terpene phytoalexins; and (f) ability to affect the pathogens directly, by disturbing the function of their cell membranes or by inactivating their ribosomes. Examples of transgenic plants with increased immunity against pathogens are also provided.     

Cells transformed by Rous sarcoma virus release transforming growth factors

Chicken embryo fibroblasts and hamster BHK cells transformed by Rous sarcoma virus (RSV) release in their culture media growth factors which enhance markedly anchorage-independent colony formation in gelified medium, at the restrictive temperature (41 degrees 5 C), of chicken embryo fibroblasts (CEF) infected by RSV mutants with a ts mutation of the src gene. This action is not observed with uninfected CEF, and, therefore, appears to require some expression of the viral src gene in the target cells. The enhancing factors are proteins related to the family of the transforming growth factors (TGFs) by their molecular weight (about 20 kd), their heat and acid resistance, and their sensitivity to dithiothreitol. They do not compete with 125I EGF for binding on the EGF receptors of the membrane of A431 cells. As chicken embryo fibroblasts are devoid of EGF receptors, their activity is not potentiated by EGF.     

Does Host Value Influence Female Aggressiveness,Contest Outcome and Fitness Gain in Parasitoids?

Intraspecific competition for resources is common in animals and may lead to physical contests. Contest outcomes and aggressiveness can be influenced by the resource holding potential of contestants but also by their perception of the resource value (RV). Competitors may assess resource quality directly (real RV) but may also estimate it according to their physiological status and their experience of the habitat quality (subjective RV). In this article, we studied contests between females of the solitary parasitoid Pachycrepoideus vindemmiae Rondani (Hymenoptera: Pteromalidae) when exploiting simultaneously a host, a Delia radicum L. (Diptera: Anthomyiidae) pupa. We tested the effect of factors modifying host value on the occurrence of agonistic behaviours, contest outcomes and host exploitation. The factors tested were: the quality of the previous habitat experienced by females, female egg load, host parasitism status and the stage reached by the owner female in her behavioural oviposition sequence. Females successfully protected their host against intruders during its exploitation, but not after oviposition, and their aggressiveness did not seem to be influenced by their perception of the RV. The fact that the host is subsequently parasitized by the opponent females appears to mainly depend on the host selectiveness of females.     

Observations of the primordial germ cells in blood samples from the chick embryo

Primoridal germ cells (PGCs) from the circulating blood in 2-day chick embryos were observed by histochemical techniques in smear preparation and by phase contrast microscopy in fresh samples. In the blood smear, PGCs were readily distinguished from blood cells by their large size (15–20 μm in diameter) and by the round and large nuclei (8–10 μm in diameter) occupying eccentrically the greater parts of the cells. Histochemically, they were demonstrated to contain abundant glycogen, a lesser amount of yolk granules (by the PAS reaction), and a large amount of lipid droplets (by the Oil red O and Sudan black B stains) in their cytoplasm. Alkaline phosphatase activity was proved slightly in their cytoplasm by the simultaneous diazo coupling method. In phase contrast microscopy, living PGCs in the blood and from the primitive gonad of 3-day embryos in parts of the examinations were observed to change their shape in somewhat amoeboid fashion, suggesting their capability for locomotion as a possible mechanism of the migration of PGCs in vivo.     

The regulation of genes and genomes by small RNAs

A recent Keystone Symposium on 'MicroRNAs and siRNAs: Biological Functions and Mechanisms' was organized by David Bartel and Shiv Grewal (and was held in conjunction with 'RNAi for Target Validation and as a Therapeutic', organized by Stephen Friend and John Maraganore). The 'MicroRNAs and siRNAs' meeting brought together scientists working on diverse biological aspects of small regulatory RNAs, including microRNAs, small interfering RNAs (siRNAs) and Piwi-interacting RNAs (piRNAs and rasiRNAs). Among the themes discussed were the diversity of small regulatory RNAs and their developmental functions, their biogenesis, the identification of their regulatory targets, their mechanisms of action, and their roles in the elaboration of multicellular complexity.     

Parental Self-Feeding Effects on Parental Care Levels and Time Allocation in Palestine Sunbirds

The trade-off between parents feeding themselves and their young is an important life history problem that can be considered in terms of optimal behavioral strategies. Recent studies on birds have tested how parents allocate the food between themselves and their young. Until now the effect of food consumption by parent birds on their food delivery to their young as well as other parental activities has rarely been studied. I have previously shown that parent Palestine sunbirds (Nectarinia osea) will consume nectar and liquidized arthropods from artificial feeders. However, they will only feed their young with whole arthropods. This provided a unique opportunity to experimentally manipulate the food eaten by parents independent of that fed to their offspring. Here, I hypothesized that parents invest in their current young according to the quality of food that they themselves consume. Breeding pairs with two or three nestlings were provided with feeders containing water (control), sucrose solution (0.75 mol) or liquidized mealworms mixed with sucrose solution (0.75 mol). As food quality in feeders increased (from water up to liquidized mealworms mixed with sucrose solution): 1) Parents (especially females) increased their food delivery of whole arthropod prey to their young. 2) Only males increased their nest guarding effort. Nestling food intake and growth rate increased with increasing food quality of parents and decreasing brood size. These results imply that increasing the nutrient content of foods consumed by parent sunbirds allow them to increase the rate at which other foods are delivered to their young and to increase the time spent on other parental care activities.     

Diacylglycerol kinases as sources of phosphatidic acid

There are ten mammalian diacylglycerol kinases (DGKs) whose primary role is to terminate diacylglycerol (DAG) signaling. However, it is becoming increasingly apparent that DGKs also influence signaling events through their product, phosphatidic acid (PA). They do so in some cases by associating with proteins and then modifying their activity by generating PA. In other cases, DGKs broadly regulate signaling events by virtue of their ability to provide PA for the synthesis of phosphatidylinositols (PtdIns).     

几种植物组织及其原生质体过氧化物酶同工酶的比较研究

对马尾松幼苗子叶和胚轴、甘蔗、小麦、烟草、黄花菜等幼叶及其原生质体的过氧化物酶同工酶(POI)分别作比较研究。观察到凡经纤维素酶处理的各植物组织POI酶带数均多于未经纤维素酶处理的组织的酶带数;除个别例外,后者一般又比无壁原生质体的酶带数多。此种差异随植株生长年龄而增大,表明植物组织内大部分POI主要存于质外体中。