Social and reproductive behavior of three mouthbrooding cardinalfishes,Apogon doederleini,A. niger and A. notatus

Synopsis Social and reproductive behavior of three paternal mouthbrooding cardinalfishes (Apogonidae) were investigated in the shallow marine waters of Shirahama, Japan. The solitary species Apogon doederleini and A. niger bred in transient pairs, in which a male and female associated for only a few hours of each afternoon on less than 5 successive days. The prespawning behavior was the same as the courtship display on days prior to spawning. After spawning, egg-incubating males were usually left alone. The gregarious species Apogon notatus formed territorial lasting pairs, which resided at given sites from dawn to dusk on each day during a period of a month or more. After spawning, the egg-incubating male either continued to stay with his mate in the territory, or left it to enter into an aggregation. In the latter case, the female continued to reside in the territory, pairing with a new male whom she brought from an aggregation. It is suggested that in paternal apogonids the prolonged pair bond and territoriality should have developed only in gregarious species as secondary adaptation for reproductive success: to avoid conspecific interference during spawning.     

cGMP、cAMP及两种cAMP衍生物对大鼠肝细胞核体外转录系统的影响

 本文介绍了以α-鹅膏蕈碱和低浓度KCl为手段建立了RNA聚合酶Ⅰ、RNA聚合酶Ⅱ活性的细胞核转录系统进而研究了cGMP、cAMP、cAMP丁酯及cAMP硫代环磷酰二乙胺对大鼠肝细胞核中RNA聚合酶Ⅰ与Ⅱ活性的影响。结果显示cGMP可以提高RNA聚合酶Ⅰ的活性;cAMP主要提高RNA聚合酶Ⅱ的活极,而cAMP分子结构变化产生的丁酯及硫代环磷酰二乙胺衍生物可增强cAMP的这种作用,为深入研究cAMP的构效关系提供了实验依据。     

The role of expert systems in vegetation science

An area of artificial intelligence known as experts systems (or knowledge-based systems) is being applied in many areas of science, technology and commerce. It is likely that the techniques will have an impact on vegetation science and ecology in general. This paper discusses some of those impacts and concludes that the main effects will be in areas of applied ecology especially where ecological expertise is needed either quickly (e.g. disaster management) or across a wide range of ecological disciplines (e.g. land management decisions). Expert systems will provide ecologists with valuable tools for managing data and interacting with other fields of expertise. The impact of expert systems on ecological theory will depend on the degree to which deep knowledge (i.e. knowledge based on first principles rather than on more empirical rules) is used in formulating knowledge bases.     

The in vitro screening of methylated 4-oxypiperidine compounds for inhibition of protein synthesis in a rabbit reticulocyte cell-free translation system

A variety of methylated 4-oxypiperidine derivatives were tested for their ability to inhibit protein synthesis in vitro. A direct correlation was found between the extent of methylation of these compounds and their inhibitory activity in a rabbit reticulocyte lysate cell-free translation system.Abbreviation IC₅₀ 50% inhibitory concentration     

Experimental study of synchronization phenomena under periodic light irradiation of a nonlinear chemical system

A photosensitive chemical oscillating reaction, i.e., the Briggs-Rauscher (B.R.) reaction, exhibiting a wealth of nonlinear behavior, when performed in a continuous-flow stirred-tank reactor, and subjected to periodic light irradiation, is studied as an experimental example of entrainment phenomena observable in biological systems. The adaptation patterns under periodic light irradiation are elucidated by means of the response of the system to continuous and single-pulse light irradiation. It is shown that self-oscillating states, excitable steady states and bistable systems can exhibit the same types of synchronization patterns when submitted to periodic external forces with appropriate amplitude and time scale conditions.     

A novel, “hidden” penicillin-induced death of staphylococci at high drug concentration,occurring earlier than murosome-mediated killing processes

In log-phase cells of staphylococci, cultivated under high, non-lytic concentrations of penicillin G, there occurred a novel killing process hitherto hidden behind seemingly bacteriostatic effects. Two events are essential for the apprearance of this hidden death: (i) the failure of the dividing cell to deposit enough fibrillar cross-wall material to be welded together, and (ii) a premature ripping up of incomplete cross walls along their splitting system. Hidden death started as early as 10–15 min after drug addition, already during the first division cycle. It was the consequence of a loss of cytoplasmic constituents which erupted through peripheral slit-like openings in the incomplete cross walls. The loss resulted either in more or less empty cells or in cell shrinkage. These destructions could be prevented by raising the external osmotic pressure. In contrast, the conventional non-hidden death occurred only much later and exclusively during the second division cycle and mainly in those dividing cells, whose nascent cross walls of the first division plane had been welded together. These welding processes at nascent cross walls, resulting in tough connecting bridges between presumptive individual cells, were considered as a morphogenetic tool which protects the cells, so that they can resist the otherwise fatal penicillin-induced damages for at least an additional generation time (morphogenetic resistance system). Such welded cells, in the virtual absence of underlying cross-wall material, lost cytoplasm and were killed via ejection through pore-like wall openings or via explosions in the second division plane and after liberation of their murosomes, as it was the case in the presence of low, lytic concentrations of penicillin. Bacteriolysis did not cause any of the hitherto known penicillin-induced killing processes.Dedicated to Prof. Dr. Georg Henneberg on the occasion of his 85th birthday     

Testicular main ducts and spermatic ducts in some cyprinid fishes I. Morphology, fine structure and histochemistry

Alburnus alburnus, Leuciscus cephalus and Vimba vimba efferent duct systems of the male gonads consist of testicular main ducts and spermatic ducts. These have similar histological, fine structural and (enzyme–) histochemical characteristics and function in (1) storage and (2) nutrition of spermatozoa, (3) synthesis of steroid glucuronides, (4) secretion of proteins and enzymes (5) formation of an ionic gradient in the seminal fluid and (6) they have auto– and heterophagocytotic activities. Therefore testicular main ducts and spermatic ducts are important in the formation of the seminal fluid.     

Enzyme IIBcellobiose of the phosphoenol-pyruvate-dependent phosphotransferase system of Escherichia coli: backbone assignment and secondary structure determined by three-dimensional NMR spectroscopy.

The assignment of backbone resonances and the secondary structure determination of the Cys 10 Ser mutant of enzyme IIBcellobiose of the Escherichia coli cellobiose-specific phosphoenol-pyruvate-dependent phosphotransferase system are presented. The backbone resonances were assigned using 4 triple resonance experiments, the HNCA and HN(CO)CA experiments, correlating backbone 1H, 15N, and 13C alpha resonances, and the HN(CA)CO and HNCO experiments, correlating backbone 1H,15N and 13CO resonances. Heteronuclear 1H-NOE 1H-15N single quantum coherence (15N-NOESY-HSQC) spectroscopy and heteronuclear 1H total correlation 1H-15N single quantum coherence (15N-TOCSY-HSQC) spectroscopy were used to resolve ambiguities arising from overlapping 13C alpha and 13CO frequencies and to check the assignments from the triple resonance experiments. This procedure, together with a 3-dimensional 1H alpha-13C alpha-13CO experiment (COCAH), yielded the assignment for all observed backbone resonances. The secondary structure was determined using information both from the deviation of observed 1H alpha and 13C alpha chemical shifts from their random coil values and 1H-NOE information from the 15N-NOESY-HSQC. These data show that enzyme IIBcellobiose consists of a 4-stranded parallel beta-sheet and 5 alpha-helices. In the wild-type enzyme IIBcellobiose, the catalytic residue appears to be located at the end of a beta-strand.     

Maximization of recombinant protein yield in the insect cell/baculovirus system by one-time addition of nutrients to high-density batch cultures

Suspension cultures of Sf-9 cells at different stages of growth were infected with a recombinant baculovirus expressing -galactosidase, using a range of multiplicities of infection (MOI) of 0.05 to 50. Following infection, the cells were resuspended either in the medium in which they had been grown or in fresh medium. Specific -galactosidase yields were not markedly affected by either MOI or medium change in cultures infected in early exponential phase (3×10⁶ cells mL^–1). In cultures infected at later growth stages, -galactosidase yields could only be maintained by medium replacement. The possibility that this requirement for medium replacement is due either to the accumulation of an inhibitory byproduct or nutrient limitation was examined. Alanine, a major byproduct of cultured insect cell metabolism, did not significantly reduce recombinant protein yield when added to infected cultures in concentrations of up to 40 mM. Following a factorial design, various nutrient concentrates were added alone or in combination to cultures infected in late exponential phase. Additions that included both yeastolate ultrafiltrate and an amino acid mixture restored specific -galactosidase yields to levels observed at earlier growth stages or in late stages with medium replacement; the addition of these concentrates, by permitting production at higher cell density, led to increases in the volumetric yield of recombinant protein. Together or separately, the concentrates when added to uninfected late exponential phase cultures, lead to a doubling of the maximum total cell protein level normally supported by unamended medium.     

Sexual differentiation of brain and behavior in the zebra finch: Critical periods for effects of early estrogen treatment

In order to determine the critical period(s) during which estrogen alters sexually dimorphic behavior and neuroanatomy in zebra finches (Poephila guttata), nestlings were injected daily 20 μg estradiol benzoate (EB) during posthatching week 1, week 2, week 3, or weeks 1, 2, and 3. At 7 months of age, birds were implanted with testosterone propionate and tested with female partners for singing, dancing, and copulatory mounting. Brains were subsequently processed for morphometry, and the volumes of the song system nuclei HVC, area X, and RA and the soma sizes and densities of neurons in RA were determined. Males given EB during week 1 failed to mount. Females given EB during week 1 were fully masculinized with respect to dancing and RA neuron soma size and density, and were partially masculinized with respect to song nuclei volumes and singing. Treatment beginning after week 1 was ineffective or less effective for all measures. Only for RA neuron measures was treatment for all three weeks more effective than week 1 treatment. Thus the first post-hatching week is the most influential period of those tested for effects of exogenous estrogen on sexual differentiation in this species, and is a period during which both masculinization of females and demasculinization of males is possible. 1994 John Wiley & Sons, Inc.