Protracted analgesia in young and adult rats maternally exposed to methadone

Summary The analgesic response to the hot-plate test was studied in 21-, 45-, 60-, 120- and 300-day-old rats maternally exposed to methadone (5 mg/kg). An elevation in nociceptive threshold, in the absence of further exposure to methadone, was observed in young and adult rats perinatally subjected to methadone.This research was supported by grant DA 01618.     

A large nucleolar U3 ribonucleoprotein required for 18S ribosomal RNA biogenesis

Although the U3 small nucleolar RNA (snoRNA), a member of the box C/D class of snoRNAs, was identified with the spliceosomal small nuclear RNAs (snRNAs) over 30 years ago, its function and its associated protein components have remained more elusive. The U3 snoRNA is ubiquitous in eukaryotes and is required for nucleolar processing of pre-18S ribosomal RNA in all organisms where it has been tested. Biochemical and genetic analyses suggest that U3 pre-rRNA base-pairing interactions mediate endonucleolytic pre-rRNA cleavages. Here we have purified a large ribonucleoprotein (RNP) complex from Saccharomyces cerevisiae that contains the U3 snoRNA and 28 proteins. Seventeen new proteins (Utp1 17) and Rrp5 were present, as were ten known components. The Utp proteins are nucleolar and specifically associated with the U3 snoRNA. Depletion of the Utp proteins impedes production of the 18S rRNA, indicating that they are part of the active pre-rRNA processing complex. On the basis of its large size (80S; calculated relative molecular mass of at least 2,200,000) and function, this complex may correspond to the terminal knobs present at the 5' ends of nascent pre-rRNAs. We have termed this large RNP the small subunit (SSU) processome.     

Radioimmunoassay of polyacrylamide

Summary Antiserum to polyacrylamide has been produced in rabbits. It can be used in a sensitive radioimmunoassay for quantitation of polyacrylamide at very low concentrations. This novel approach to the analysis of a synthetic, biologically inactive, hydrocarbon polymer has potentially widespread implications, for example, in the downstream measurement of flocculating agents used in water purification treatments.Acknowlegment. We thank L. P. McCarty for coordination of the project, F. A. Blanchard for synthesis of the¹⁴C-PAA, and C. Brown and J. Cuan for technical assistance in the biological studies.     

SMC1beta-deficient female mice provide evidence that cohesins are a missing link in age-related nondisjunction

Mitotic chromosome segregation is facilitated by the cohesin complex, which maintains physical connections between sister chromatids until anaphase. Meiotic cell division is considerably more complex, as cohesion must be released sequentially to facilitate orderly segregation of chromosomes at both meiosis I and meiosis II. This necessitates meiosis-specific cohesin components; recent studies in rodents suggest that these influence chromosome behavior during both cell division and meiotic prophase. To elucidate the role of the meiosis-specific cohesin SMC1beta (encoded by Smc1l2) in oogenesis, we carried out meiotic studies of female SMC1beta-deficient mice. Our results provide the first direct evidence that SMC1beta acts as a chiasma binder in mammals, stabilizing sites of exchange until anaphase. Additionally, our observations support the hypothesis that deficient cohesion is an underlying cause of human age-related aneuploidy.     

Animal behaviour: coalition among male fiddler crabs

Until now, no compelling evidence has emerged from studies of animal territoriality to indicate that a resident will strategically help a neighbour to defend its territory against an intruder. We show here that territory-owning Australian fiddler crabs will judiciously assist other crabs in defending their neighbouring territories. This cooperation supports the prediction that it is sometimes less costly to assist a familiar neighbour than to renegotiate boundaries with a new, and possibly stronger, neighbour.     

油菜不同部位分枝籽粒生产力对氮肥反应的差异

研究了不同氮肥用量对杂交油菜“秦油2号“主序及各分枝生产力的影响.结果表明, 随着氮肥用量的增加,主序产量占单株产量的比例逐渐降低,施氮量过大则又略有回升.主序籽粒约占产量1/4时,单株产量最高;在不同氮肥用量下,上部分枝生产力的变化趋势类似于主序,而中部分枝则与全株一致;在分枝产量构成因素中,氮肥用量对分枝角果数的影响最大;主序及上位分枝中氮素累积量受氮肥用量的影响程度较小,而中下位分枝则较大.