2-Chlorobenzoic acid and 2,5-dichlorobenzoic acid metabolism by crude extracts of Pseudomonas sp. CPE2 strain

F. FAVA, F. BALDONI AND L. MARCHETTI. 1996. Crude extracts of Pseudomonas sp. CPE2 strain, which is capable of growing on 2-chlorobenzoic acid (2–CBA) and 2,5–dichlorobenzoic acid (2,5–dCBA) in the absence of other carbon sources, were found to be capable of bioconverting 2–CBA and 2,5–dCBA to catechol and 4–chlorocatechol, respectively, by a reaction requiring molecular oxygen and exogenous NADH. Extracts obtained from 2–CBA-grown cells in the presence of 2–CBA and from 2,5–dCBA-grown cells in the presence of 2,5–dCBA were found to have activities similarly influenced by the assay parameters pH, temperature, and by concentration of oxygen, protein, Fe²⁺, FAD and NADH in the assay medium. In addition, the activity of the two crude extracts in the presence of 2–CBA or 2,5–dCBA was described by very similar Michaelis-Menten kinetic parameters. These observations led to the speculation that a unique broad-spectrum chlorobenzoate 1,2–dioxygenase catalyses the 2–CBA and 2,5–dCBA metabolism both in 2–CBA-and 2,5–dCBA-grown CPE2 cells.     

Stress-induced ripening of the non-ripening tomato mutant nor

Tomato ( Lycopersicon esculentum Mill.) plants of the non-ripening mutant nor (3rd backcross to the normal cultivar Rutgers) were grown under water stress induced in two different ways: a) reduction of water supply and b) increase in transpiration rate by adding kinetin to the nutrient solution. Both drought treatments induced fruits of the non-ripening mutant nor to ripen, that is, the parameters characteristic of ripening – red pigment, taste, pectolytic activity, softening, and the evolution rates of CO₂ and ethylene – all increased, although not to the normal level. Such an increase does not normally take place in the nor mutant under control conditions. It is suggested that fruits of the nor mutant can be induced to ripen by any kind of water stress. The induction mechanism is still to be explored.     

Amidation of β-Amyloid Peptide Strongly Reduced the Amyloidogenic Activity Without Alteration of the Neurotoxicity

Abstract: β-Amyloid accumulates in cerebral deposits in Alzheimer's disease, so to test the correlation between the neurotoxic and fibrillogenic capacity of β-amyloid, we synthesized a peptide homologous to fragment 25–35 of β-amyloid (β25–35) and amidated at the C-terminus (β25–35-NH₂). As the amidation strongly reduced the amyloidogenic capacity of β25–35, we compared its neurotoxic activity in the amidated (β25–35-NH₂) and nonamidated forms. The viability of primary cultures from fetal rat hippocampus was reduced in a dose-related manner (10–100 µ M ) similarly by β25–35 and β25–35-NH₂, whereas a scrambled peptide, amidated or nonamidated, did not alter the neuronal viability. The neurotoxic activity of β25–35-NH₂ is mediated by apoptosis as demonstrated by morphological and biochemical investigations. Electron microscopy examination of culture media with β25–35 or β25–35-NH₂ incubated with neuronal cells for 7 days confirmed the high level of fibrillogenic activity of β25–35 and the almost total absence of fibrils in the solution with β25–35-NH₂. Furthermore, staining with thioflavine S was used to identify amyloid fibrils, and only the cultures exposed to β25–35 exhibited intense staining associated with neuronal membranes. These data indicate that the neurotoxic activity of the β-amyloid fragment is independent of the aggregated state of the peptide.     

Reproductive biology and growth of the goatfish, Parupeneus barberinus (Lacepede), in Aqaba, Jordan

Monthly changes in the gonadosomatic index indicate that the main spawning season of Parupeneus barberinus in Aqaba extends from May to August for females and from May to June for males. Males in the 4 years age-group (63–4%) and the 5 years age-group (65–1%) are predominant. The von Bertalanffy growth equation parameters calculated from mean total length data are: L_α= 32–8cm; K=0–225; (t_o=−0–73 for males and L_α= 32–7cm; K=0–206; t_o= −0.82 for females. The length-weight regression coefficients for males (2.85) and females (2.8) are not significantly different and they indicate a negative allometric growth. There is no significant change in condition factor with age.     

Seasonal changes in some blood chemistry parameters and in relative liver and gonad weights of pike (Esox lucius L.) from the River Danube

Samples from a natural population of pike (Esox lucius L.) from the River Danube were used in a 12-month study to determine seasonal variations in biochemical parameters of pike blood sera, hepatosomatic index (HSI) and gonadosomatic index (GSI). The ranges of enzyme activities for sample means were: aspartate aminotransferase (ASAT) 252.0–583.8 U 1⁻¹, alanine aminotransferase (ALAT) 4.9–11 -2 U1 and alkaline phosphatase (AP) 39.5–91.8 U1⁻¹. The ranges of other parameters analysed in serum were total protein 27.7–40.1 g 1 ¹, urea 0.57–l.52 mmol 1 ¹ and creatinine 21.2–118.6 μmol 1 ¹. The range of sample means for HSI and GSI were 1.28–4.16 and 0.07–20.2 respectively. Temperature ranged from 4.5 to 23.5°C. The activity of serum AP was positively correlated to water temperature in males only, while urea and creatinine showed a positive correlation to water temperature in individuals of both sexes. GSI was correlated significantly with HSI in females. Total protein reached the lowest values during the spawning period, while creatinine levels depended on both the sex and season.     

Relationship between iron chlorosis and alkalinity in Zea mays

Mengel, K. and Geurtzen, G. 1988. Relationship between iron chlorosis and alkalinity in Zea mays . - Physiol. Plant. 72: 460–465.
Maize ( Zea mays L. cv. Anjou 21) grown in nutrient solution with Fe-EDTA and with nitrate as the sole nitrogen source showed typical Fe-chlorosis symptoms after a growth period of 14–21 days. Alkalinity in roots, stems and leaves of the chlorotic plants was high. Transferring the chlorotic plants from the nitrate-containing nutrient solution to a solution of (NH₄)₂SO₄ resulted in a regreening of leaves within 2–3 days which was associated with a decrease in solution pH, a decrease in alkalinity of plant parts, a translocation of Fe from roots to tops and a release of Fe into the outer solution. Similar effects were obtained when Fe chlorotic plants were transferred to a dilute HO solution with pH 3.5.
Spraying chlorotic leaves with indoleacetic acid or with fusicoccin led also to a regreening of leaves without having a major effect on leaf alkalinity.
Interpretation of the experimental results is based on the assumption that nitrate as sole N source leads to a high pH level in the apoplast resulting in the precipitation of Fe compounds, probably Fe oxide hydrate. Ammonium nutrition has the reverse effect since it lowers the apoplast pH and this can result in the dissolution of Fe compounds. Application of indoleacetic acid as well as fusicoccin supposedly stimulates the proton pumps in the plasmalemma of the leaf tissue. The resulting decrease in apoplast leaf pH in the microenvironment also leads to a dissolution of Fe compounds in the apoplast and thus promotes the uptake of Fe by the symplasm.     

Increased adult mortality and reduced breeding success with age in a population of common guillemot Uria aalge using marked birds of unknown age

Although there is general consensus about the existence of senescence in vertebrates, empirical evidence of senescence in demographic parameters in wild populations is limited. Data on breeding success and survival of breeding common guillemots Uria aalge were collected over 20 years on the Isle of May (Scotland) using a pool of individuals marked as adults. Because the years of hatching of individuals were not known, we used the time (years) elapsed since first capture (TFC) as a measure of age. The use of this proxy did not create any bias in estimating senescence in the case of a linear decline, nor did it greatly decrease the power of a test for senescence. Breeding success declined significantly from 0.81 (95% CI: 0.77–0.84) to 0.62 (0.54–0.68) over the study period. It also varied in relation to age, initially increasing (from 0.62 (0.54–0.68) at TFC of 0 year to 0.76 (0.73–0.79) at TFC of 9 years) up to a plateau (from TFC of 9 years with 0.76 (0.73–0.79) until TFC of 13 years with 0.77 (0.74–0.79) before declining in later life to 0.70 (0.61–0.78) at TFC of 19 years). Survival was generally high and varied significantly from year to year. It also declined with TFC: survival of birds marked in 1982 decreased from 0.92 (0.85–0.96) at a TFC of 0 year to 0.88 (0.82–0.92) at a TFC of 19 years. Resighting probabilities also declined with TFC suggesting that the oldest birds do not come back to the colony to breed as regularly as younger individuals. These findings indicate that individual common guillemots on the Isle of May showed both actuarial and reproductive senescence.     

Normal ranges of some blood chemistry parameters in adult farmed Atlantic salmon, Salmo salar

Blood samples from healthy adult Atlantic salmon fed an optimal diet in net sea pens were collected at intervals from October to May. Haematological determinations and biochemical serum analyses were carried out on 20 fish in each of seven samples. The ranges of haemato-logical values for sample means were: haematocrit 44–49%, haemoglobin 8.9–10.4 g 100ml⁻¹, red blood cell count 0.85–1.10 × 10¹² l⁻¹, MCV 441–553 × 10⁻¹⁵ 1, MCH 94–106 × 10⁻⁶ g, MCHC 19.4–21.7 g 100ml⁻¹ and leucocrit 0.43–0.96%. The ranges of enzyme activities in serum, for sample means, were: alkaline phosphatase 647–988Ul⁻¹, aspartate aminotrans-ferase 202–351 Ul⁻¹ and alanine aminotransferase 4–8 Ul⁻¹. The ranges of the other parameters analyzed in serum were: total protein 41.6–56.6 gl⁻¹, albumin 18.3–24.3 gl⁻¹, albumin/total protein ratio 39.3–44.0%, creatinine 26–46 μmol, triglycerides 2.53–4.98 μmol and cholesterol 9.3–12.8 μmol. These values are considered to be the normal ranges in healthy fish. Variations due to seasonal changes, and the clinical significance of the selected parameters, are discussed. Data showing the reproducibility of the biochemical analyses in serum are presented.     

Genetic differentiation in Plantago major: Growth and root respiration and their role in phenotypic adaptation

The root respiration and the growth of plants of four inbred lines of Plantago major L. were followed at two levels, of mineral nutrition. In addition the response to a transfer of plants from one condition to the other was studied. The activities of the cytochrome and of the alternative pathway wee determined and used to distinguish between genetic differences among the inbred lines and the plasticity within each inbred line. Root respiration and growth parameters differed significantly between the lines and were directly related to seed number per capsule (low respiratory activity and slow growth – 11 seeds per capsule; high respiratory activity and fast growth – 33 seeds per capsule).
Plasticity of respiration and growth parameters is expressed as differences in the total respiration, the activities of the cytochrome and of the alternative pathway, and in the shoot to root ratio, as a response to nutritional level or to changes of the strength of the nutrient solution. Differences in this plasticity in the four selected lines and in quickness of response to a change in mineral nutrition were directly related to the ecological strategy. These results are discussed in relation to the strategy of the genotypes for survival in the field. The high growth rate and the presence of plasticity in line 4 (ssp. Pleiosperma ) make this genotype act like an annual, following a ruderal strategy. The lower growth rate and the absence of plasticity in line 1 (ssp. major ) fit a more competitive strategy.     

Characterization of indoles by thin-layer chromatography and in situ fluorometry

The characterization of microgram quantities of a number of naturally occurring and synthetic indoles through a combination of thin-layer chromatography and in situ fluorescence spectroscopy is reported. Instrumental detection limits of 0.03–0.05 μg of the indoles are possible using the native fluorescence of the indoles in the ultraviolet range, with excitation maxima in the range 285–310 nm and emission maxima in the range 345–360 nm. Spraying with a dilute acid solution (0.1 N H₂SO₄ in methanol) produces an additional pair of maxima, with excitation at about 350 nm and emission at about 450 nm. The presence of a polar compound such as sulfuric acid or dimethyl sulfoxide in the spray produces an enhancement of the indole fluorescence. The procedure should find application in the determination of indoles in biological samples.     

Immunoquantitation of human placental alkaline phosphatase using radial immunodiffusion.

A simple procedure is described for immunoquantitation of human placental alkaline phosphatase by radial immunodiffusion. Agarose gels in petri dishes were overlayed with diluted antiserum, and, after equilibration of the antibody with the gel, the overlay was poured off and the gel was used for quantitation of enzyme protein using a specific stain to amplify visualization. The method has a variation of 0–8.5% for triplicate determinations on a single plate, with a mean of 2.6%. Variations between plates were 0–13%, with a mean of 4.2%. By including Triton X-100 detergent in the overlay solution, it was possible to quantitate the amount of enzyme in membrane preparations from placentae and cancer fluids: A 1000-fold range of antiserum and enzyme dilutions was tested; over this range, only a 2–3 × deviation from the expected ring size was found. As little as 5 ng of enzyme protein could be measured by this technique.     

Fertilization Potential of the Medaka Egg

Fertilization of the medaka egg in 10% Ringer's solution generates a depolarization of 4 mV just before the appearance of a characteristically longer hyperpolarization (25). The depolarization appears to be the result of a nonspecific leak triggered by sperm stimulation and the amplitude of the depolarization is thought to be independent of [Ca²⁺]_o (25). We have investigated the ionic dependence of this depolarization. An initial small depolarization (3–4 mV; duration, 5–8 sec) is followed by a rising phase of a spike-like depolarization in the range of 10–60 mV. The amplitude of this spike-like depolarization is propodional to log [Ca²⁺], ranging from 0.33–18 mM. Calcium antagonists, e.g. 10 mM cobalt or 10 μg/ml verapamil in 10% Ringer do not block the depolarization in the presence of 1.1 mM CaCl₂.     

A competitive coexistence principle?

Competitive exclusion – n species cannot coexist on fewer than n limiting resources in a constant and isolated environment – has been a central ecological principle for the past century. Since empirical studies cannot universally demonstrate exclusion, this principle has mainly relied on mathematical proofs. Here we investigate the predictions of a new approach to derive functional responses in consumer/resource systems. Models usually describe the temporal dynamics of consumer/resource systems at a macroscopic level – i.e. at the population level. Each model may be pictured as one time-dependent macroscopic trajectory. Each macroscopic trajectory is, however, the product of many individual fates and from combinatorial considerations can be realized in many different ways at the microscopic – or individual – level. Recently it has been shown that, in systems with large enough numbers of consumer individuals and resource items, one macroscopic trajectory can be realized in many more ways than any other at the individual – or microscopic – level. Therefore, if the temporal dynamics of an ecosystem are assumed to be the outcome of only statistical mechanics – that is, chance – a single trajectory is near-certain and can be described by deterministic equations. We argue that these equations can serve as a null to model consumer-resource dynamics, and show that any number of species can coexist on a single resource in a constant, isolated environment. Competition may result in relative rarity, which may entail exclusion in finite samples of discrete individuals, but exclusion is not systematic. Beyond the coexistence/exclusion outcome, our model also predicts that the relative abundance of any two species depends simply on the ratio of their competitive abilities as computed from – and only from – their intrinsic kinetic and stoichiometric parameters.     

Water relations of Picea abies. I. Comparison of water relations parameters of spruce shoots examined at the end of the vegetation period and in winter

Seasonal changes of some water relations parameters of Norway spruce shoots ( Picea abies [L.] Karst.) were studied during two experiments using the pressure-volume analysis. For each experiment only shoots of a single tree were used.
During the first study, the course of the turgor loss point (as bulk osmotic pressure when turgor first reaches zero, πp) of shoots developed in late 1986 vegetation period, were measured in 1987. The turgor loss point decreased temporarily from –2.5 MPa at the beginning of the year to –3.3 MPa at the end of March, but then increased to the original level for the rest of the year.
During the second study, water relations parameters were measured in late summer 1987 and in late winter 1988. Winter shoots at full water saturation contained up to 20% less water than in late summer. Accordingly, the bulk osmotic pressure at full water saturation (π_p) decreased from –1.7 MPa in late summer to –1.9 MPa in winter, π_p decreased also from –2.2 MPa to –2.8 MPa. However, the amount of osmotically active substances (mOsmol, N) remained unchanged. The relative amount of apoplastic water in the total shoot water content appeared to drop insignificantly from 17% to 15%.
The results show that the decrease in π_o and π_p in late winter is not due to an accumulation of osmotically active substances in the vacuoles but is due to a decrease in tissue water content. The temporary reduction of the symplastic volume by deposition of osmotically inert substances seems to be the most probable cause of this phenomenon.     

Growth of the clupeid fishes, Stolothrissa tanganicae and Limnothrissa miodon, in the Zambian waters of Lake Tanganyika

The age and growth of two endemic Lake Tanganyikan clupeid fishes, Stolothrissa tanganicae and Limnothrissa miodon , were estimated from analysis of otolith microstructure in specimens collected in Zambian waters from October to December 1990. Both species had relatively clear, concentric otolith increments which were believed to represent daily increments based on their similarity to daily increments found in some marine clupeid species. The growth rates estimated from length-at-age data were: for S. tanganicae, L_t = 104·0 (1 – exp (– 0.00512 ( t – 5·8))); for L. miodon, L_t = 155.4 (1 – exp (– 0.00236 ( t +8.1))). In most cases, the growth parameters obtained from otolith analyses generally agreed with those previously estimated from analyses of length-frequency distributions.     

Strength of concave septa and depth limits of fossil cephalopods

Westermann, G. E. G.: Strength of concave septa and depth limits of fossil cephalopods.
Simple septa with spherical curvature are present in the shells of all Endocer-oidea, Actinoceroidea, Bactritoidea, and most Nautiloidea and Coleoidea. Such septa act as quasi-hemispherical concave membranes when subjected to hydrostatic pressure. Since the tensile strength of a spherical membrane is directly proportional to the ratio of its thickness and radius of curvature, measurements of these parameters on polished and thin sections of septa can be used to obtain strength of the septum against implosion. Depth limits of fossil cephalopods can be made by calibrating these measurements in terms of recent implosion data on 'living' Spirula and Nautilus . Estimates of septal strength are augmented by strength estimates for long septal necks and cylindrical to globular connecting rings.
Assuming that actual habitats ranged to approximately two-thirds of the mechanical limits of the shells, the following maximum depth ranges are indicated from this preliminary survey: Endoceroidea 100–450 m; Actinoceroidea 50–150 m; Nautiloidea, Ellesmerocerida 50–200 m, Orthocerida 150–500 m, Oncocer-ida <150, Discosorida <100 m, Tarphycerida <150 m, Nautilida 200–600 m; Bactritoidea c. 400 m; Coleoidea, Aulacocerida 200–900 m, Sepiida 200–1000 m, Belemnitida 50–200 exceptionally 350 m.     

NaCl胁迫下平邑甜茶根系线粒体特性和细胞死亡特征

以平邑甜茶(Malus hupehensis var. pingyiensis)实生幼苗为试验材料, 研究NaCl浇灌后根系线粒体H₂O₂含量、膜电位(Δψm)和根系ATP含量的变化以及细胞死亡特征。结果表明, 根系线粒体H₂O₂含量在0.085 mol·L ^-1 NaCl处理的第1-6天逐渐降低, 在第6-15天则快速上升; 线粒体Δψm在0.085 mol·L ^-1 NaCl处理的15天内一直呈下降趋势, 在第6-15天下降速度明显加快; 根系ATP含量在0.085 mol·L ^-1 NaCl处理的15天内始终低于对照, 但保持在一个较稳定的范围内。TUNEL原位末端标记试验显示, 0.085 mol·L ^-1 NaCl处理的第9天, 根系石蜡组织切片上的阳性反应斑点明显增多, 到第15天时阳性反应斑点密集成片, 表明细胞核DNA发生了细胞程序性死亡的特征性断裂。根系中细胞程序性死亡关键酶类caspase3/7活性在0.085 mol·L ^-1 NaCl处理的第1-6天处于较低水平, 其活性在第6-15天成倍上升。这些结果表明, 0.085 mol·L ^-1 NaCl处理6-15天能诱导平邑甜茶根细胞发生程序性死亡, 而且线粒体特性的变化与根系细胞程序性死亡密切相关。     

Growth of silver hake within the U.S. continental shelf ecosystem of the northwest Atlantic Ocean

Von Bertalanffy growth parameters were estimated for silver hake Merluccius bilinearis within four regions of the United States continental shelf ecosystem of the northwest Atlantic Ocean during 1975–1980, 1982–1987 and 1988–1992. Differences in silver hake growth were found between the Middle Atlantic and southern Georges Bank regions ( P <0–01) over all three time periods. Growth also differed between northern Georges Bank and the Gulf of Maine ( P <0–01) during 1975–1980 and 1982–1987, and significant differences between southern Georges Bank and northern Georges Bank were found only during 1982–1987. Silver hake in the Gulf of Maine exhibited larger asymptotic sizes, but attained their asymptotic size at slower rates (L₀₀= 47 cm and K =0–33) in comparison to silver hake in the Middle Atlantic ( L₀₀= 43 cm and K =0–51), while growth parameter estimates for silver hake on Georges Bank were intermediate between these. Although significant differences in growth of silver hake between the various regions are consistent with separate stocks in the U.S. continental shelf ecosystem, the growth characteristics from the different regions are inconsistent with the presently assigned stock boundaries. (c) 1996 The Fisheries Society of the British Isles     

The spermatozoon of the African catfish: fine structure, motility, viability and its behaviour in seminal vesicle secretion

The spermatozoon of the African catfish Clarias gariepinus is a simple organized aquasperm although it reveals very unique characteristics: the cytoplasmic channel is lacking, the mitochondria form a complex structure and the arrangement of the centriolar complex is species specific. Semen has high initial motility rates ( c. 70–90%) and swimming velocities ( c. 120–140 μm s⁻¹), the main swimming type is linear. Motility duration in water is 30 s and is prolonged only to 40 s in NaCl solutions or more complex bu ered motility activating saline solutions. A pH between 7.0 and 9.0 has no e ect on the sperm motility parameters. Motility is completely and reversibly suppressed in electrolyte and non-electrolyte solutions with an osmolality of 200 mosmol kg⁻¹. During immotile storage the sperm viability is influenced by the osmolality and the potassium levels of the storage medium, by the temperature and by the dilution. At optimal conditions (bu ered sperm motility inhibiting saline solution: 150 mmol l⁻¹ NaCl, 2.5 mmol l⁻¹ KCl, 1 mmol l⁻¹ CaCl₂, 1 mmol l⁻¹ MgSO₄, 20 mmol l⁻¹ Tris solution, pH 8.5; dilution rate 1: 5; storage temperature, 4°C) sperm viability persists for >7 days. High viscosity of the pure seminal vesicle secretion completely inhibits the sperm motility. When the seminal vesicle secretion is diluted in water the viscosity decreases and the motility suppressing e ect is neutralized. When semen is mixed with seminal vesicle secretion the sperm viability decreases to zero within 10 min.     

A sensitive enzymic assay for benzylpenicillin

A method has been developed for the determination of sodium benzylpenicillin concentrations in the range 3·3–33 μg/ml. 6-Aminopenicillanic acid is released from the benzylpenicillin by the action of the enzyme penicillin acylase and is estimated from its reaction with fluorescamine at pH 4.7-Aminocephalosporanic acid shows a similar trend to 6-aminopenicillanic acid in its reaction at pH 4. The open β-lactam ring form of each compound shows little fluorescence with fluorescamine at pH but shows strong fluorescence in the pH range 7–9. 6-Aminopenicillanic acid and its open β-lactam ring form give different fluorescent responses to increasing volumes of a solution of the fluorigenic agent at pH 7·8. This effect can be used to estimate concentrations in a mixture of the two components providing other amino material is absent.