Nucleotide sequence and expression of an AIDS-associated retrovirus (ARV-2)

The nucleotide sequence of molecular clones of DNA from a retrovirus, ARV-2, associated with the acquired immune deficiency syndrome (AIDS) was determined. Proviral DNA of ARV-2 (9737 base pairs) has long terminal repeat structures (636 base pairs) and long open reading frames encoding gag (506 codons), pol (1003 codons), and env (863 codons) genes. Two additional open reading frames were identified. Significant amino acid homology with several other retroviruses was noted in the predicted product of gag and pol, but ARV-2 was as closely related to murine and avian retroviruses as it was to human T-cell leukemia viruses (HTLV-I and HTLV-II). By means of an SV-40 vector in transfected simian cells, the cloned gag and env genes of ARV-2 were shown to express viral proteins.     

Retrograde signaling by Syt 4 induces presynaptic release and synapse-specific growth

The molecular pathways involved in retrograde signal transduction at synapses and the function of retrograde communication are poorly understood. Here, we demonstrate that postsynaptic calcium 2+ ion (Ca2+) influx through glutamate receptors and subsequent postsynaptic vesicle fusion trigger a robust induction of presynaptic miniature release after high-frequency stimulation at Drosophila neuromuscular junctions. An isoform of the synaptotagmin family, synaptotagmin 4 (Syt 4), serves as a postsynaptic Ca2+ sensor to release retrograde signals that stimulate enhanced presynaptic function through activation of the cyclic adenosine monophosphate (cAMP)-cAMP-dependent protein kinase pathway. Postsynaptic Ca2+ influx also stimulates local synaptic differentiation and growth through Syt 4-mediated retrograde signals in a synapse-specific manner.     

Activated expression of the N-myc gene in human neuroblastomas and related tumors

In neuroblastoma lines in which the N-myc gene is present as a single copy, the expression of N-myc as messenger RNA is increased relative to that in nonneuroblastoma cell lines and tumors. The increase of expression in neuroblastomas with amplified N-myc genes is the result of (i) an increase in the absolute amount of expression of each N-myc gene and (ii) an increase in the copy number of the N-myc gene. A second gene--which is amplified in many of the same lines as N-myc--is expressed to about the same degree in most human cell lines and primary tumors regardless of origin (when normalized to gene copy number). Thus, a change in the regulation of N-myc expression in neuroblastomas and certain other tumors results in greatly increased expression of each N-myc gene copy.     

Dissociation of bradycardia and arterial constriction during diving in the seal Phoca vitulina

Bradycardia associated with diving in the harbor seal has been dissociated from the arterial constrictor response by intracardiac pacing. Development of arterial constriction does not depend upon the development of bradycardia. During pacing, arterial constriction continues in the absence of bradycardia. Increases in heart rate to values greater than 120 beats per minute during a dive produce a progressive decrease in mean aortic pressure, which suggests that one major function of bradycardia is to reduce cardiac output, thus matching left ventricular output to the restricted vascular bed and decreased venous return associated with diving.     

Inheritance of the resistance toMeloidogyne incognita,M. javanica,andM. arenaria in potatoes

The objectives of this research were: 1) to try to determine the inheritance of the resistance toMeloidogyne incognita, M. javanica, andM. arenaria and 2) to study genetic relationships among the three species of root-knot nematodes in potatoes. The source of resistance used wasSolanum sparsipilum. The progenies analyzed in this study may be grouped into a few discrete segregation patterns, three forM. incognita andM. javanica and two forM. arenaria. More than one dominant locus, but not many loci are needed to explain the segregation obtained in the three species. Susceptible clones ofS. sparsipilum possess recessive or epistatic genes which affect the pattern of segregation for resistance, when these clones are crossed to resistant clones. Maternal effects were expressed in reciprocal crosses between susceptible and resistant clones when they were tested for resistance toM. arenaria. Clones in this study which are resistant toM. arenaria are also resistant toM. incognita andM. javanica     

典型微塑料对环丙沙星在多孔介质运移的影响

为探究微塑料对抗生素在多孔介质运移的影响,本文以聚丙烯（Polypropylene,PP）作为典型微塑料,以环丙沙星（Ciprofloxacin,CIP）为典型抗生素污染物,通过CIP的吸附实验和CIP在砂柱中运移实验,研究PP对CIP在多孔介质中的运移分布的影响。结果表明,PP对CIP的吸附能力强于石英砂对CIP的吸附能力,最大Langmuir吸附能力为1.03 mg·g^-1。在砂柱实验中,CIP的流出浓度随PP含量的增加而降低,而流速增大时砂柱流出的CIP浓度峰值的出现时间提前。此外,当进入砂柱的CIP溶液浓度增大时,流出砂柱的CIP总量增大;溶液中增加NaCl、CaCl₂和BaCl₂等电解质提高离子强度,会增强CIP在砂柱中的迁移能力。研究表明,PP能显著影响CIP在多孔介质中运移的行为。     

Screening Mangrove Endophytic Fungi for Antimalarial Natural Products

We conducted a screening campaign to investigate fungi as a source for new antimalarial compounds. A subset of our fungal collection comprising Chinese mangrove endophytes provided over 5000 lipophilic extracts. We developed an accelerated discovery program based on small-scale cultivation for crude extract screening and a high-throughput malaria assay. Criteria for hits were developed and high priority hits were subjected to scale-up cultivation. Extracts from large scale cultivation were fractionated and these fractions subjected to both in vitro malaria and cytotoxicity screening. Criteria for advancing fractions to purification were developed, including the introduction of a selectivity index and by dereplication of known metabolites. From the Chinese mangrove endophytes, four new compounds (14–16, 18) were isolated including a new dimeric tetrahydroxanthone, dicerandrol D (14), which was found to display the most favorable bioactivity profile.     

The use of a T-maze to measure cognitive–motor function in cats (Felis catus)

Few tests have been developed to evaluate the cognitive and motor capabilities of domestic cats, despite the suitability of cats for specific studies of neuroanatomy, infectious diseases, development, aging, and behavior. The present study evaluated a T-maze apparatus as a sensitive and reliable measure of cognition and motor function in cats. Eighteen purpose-bred, specific pathogen-free, male, neutered domestic short-haired cats (Felis catus), 1-2 years of age, were trained and tested to a T-maze protocol using food rewards. The test protocol consisted of positional discrimination training (left arm or right arm) to reach a predetermined criterion, followed by 2 discrimination reversal tests. The 2 reversal tests documented the ability of the subjects to respond to a new reward location by switching arms of the T-maze. Data were collected on side preference, number of correct responses, and latency of the responses by the subjects. Aided by a customized computer program (CanCog Technologies), data were recorded electronically as each cat progressed from the start box to the reward arm. The protocol facilitated rapid training to a high and consistent level of performance during the discrimination training. This learning was associated with a decrease in the latency to traverse the maze to a mean of 4.80 ± 0.87 seconds, indicating strong motivation and consistent performance. When the rewarded side was reversed in the test phase, the cats required more trials to reach the criterion, as expected, but again showed reliable learning. The latency to the reward in the first session of reversal increased 86% from the first to the last trial, indicating that it may provide a useful index of cognitive processing. Latencies subsequently decreased as the new reversal paradigm was learned. This paradigm provides a relatively rapid and reliable test of cognitive–motor performance that can be used in various settings for the evaluation of feline cognitive and motor function.