Bacterio- and zooplankton in the outfall of a tributary of a flatland water reservoir during a period of abnormal climatic conditions

Three zones were distinguished according to the electrical conductivity of water in a flatland water reservoir: the transitional zone of the tributary, the frontal zone, and the transitional zone of the inlet. According to the presence of the edge effect, the frontal zone of the outfall area is identified as an ecotone. The buffer properties of the ecotone are conductive to the reduced response of the zooplankton to the increase in water temperature during an abnormally warm year.     

Comparative study of formation of the frontal cortex of the brain of monkeys and man in ontogenesis]

The development of the fields of the frontal zone (8, 3, 10, 11, 12) were compared in the pre- and postnatal periods oflife in the nacaque-rhesus and man. The cyto-mielcarchitectonical and guantitative methods wereused. The square surfaces of the above fields were measured, their per cent ratios to thesquare surface of all the cortex, new cortex and frontal zone were calculated. The work hasrevealed the following: 1. General regularities in the development of frontal zones in monkeysand man: a) shorter terms for the formation of philogenetically old fields-11, 12, 8 andlonger terms for the new ones-9 and 10:b) predominant development of the frontal zone at theexpense of progressive young fields 9 and 10: c) predominat formation of the frontal zone bothkinds of primates in the postnatal period. 2. The specific features for each field (the termsfor isolation of the fields, the rate and direction of their development). 3.Substantial difference: more rapid maturation of the frontal zone in macaques (by the 6th -12th months of life)and more prolonged one in humans-by 12 years. A considerable growth of philogenetically newstructures (fields 9 and 10) in the system of all the cortex and the frontal zone wasshown in man as compared with monkey. The experimental ontogentical material is interpreted.     

Marn features of the thermal regime of Lake Ladoga during the ice-free period

The thermal regime of Lake Ladoga during the ice-free period is determined by primarily incoming solar radiation, wind-induced mixing and the depth distribution. The variation of water surface temperature with time for different areas of the lake is discussed using temperature measurements obtained by means of an aircraft-mounted IR-radiometer. Maximum values of water surface temperature in these areas, as well as the time lags between the areas are determined. Mean rates of temperature variation for the periods of warming and cooling of the lake are also determined. A formula for determining the location of the spring frontal zone at different stages of water warming is suggested. The peculiarities of the interaction of stratified and isothermal waters in the frontal zone, the slope of the frontal zone and the thermal balance components are discussed on the basis of specialized field measurements by using ships and aeroplane. The scales of temperature inhomogeneities are obtained based on computation of 2D spatial correlation functions.     

Organic matter transport across a macrotidal estuary grandient: the Seine estuary,Fance

The macrotidal Seine estuary receives mineral and organic fluxes from a strongly industrialized basin. Upstream-downstream analysis of POC, polysaccharides and phenolic compounds in the particulate fraction indicated clearly the continental inflow. Within the maximum turbidity zone, the organic matter/suspended particulate matter ratio is lower than elsewhere which results from the dilution effect. Particulate tracers were quantified using grain size analysis and S.E.M. techniques. These sedimentary data defined the ratio of marine to continental particulate flux and mechanisms controlling the suspended particulate matter load within the estuarine mixing zone (resuspension, frontal enrichment and turbulent mixing processes). Organic parameters confirm the data on the mineral matter and were used to distinguish between the marine and continental inputs, from the upstream and downstream samples. Between the two endmembers, variations in organic parameters were controlled mainly by the hydrodynamics in the estuarine zone, rather than by salinity changes.     

Spatial synchronization of potentials in the frontal zones of the brain during performance of nominative speech in children

Characteristics of spatial-temporal relations of the frontal zones potentials with those of other brain centres were studied in five- to six-year old children during naming of visually presented objects. EEG cross correlation analysis has shown that during visual perception of familiar objects the correlations of frontal areas with the interior pariental area of the left hemisphere are enhanced; the rhythms of the inferior parietal and occipital zones in the left hemisphere precede the potentials in the frontal area, while in the right hemispere synphasic relations are set up between the frontal and occipital zones. Naming the objects by the appropriate word as compared with rest and showing of the object, leads to enhancement of both intra- and interhemispheric correlations between potentials in the frontal zone and the inferior parietal and temporal zones. The frontal lobe rhythms begin to precede the inferior parietal and occipital potentials and form synphasic relations with the temporal and motor zone potentials in the left hemisphere.     

Spatio-temporal variation in the demography of a bunch grass in a patchy semiarid environment

Plants face different environmental pressures in different patches of vegetation mosaics, so their demography cannot be completely understood if it is not studied in each patch-type. Banded patterns of vegetation surrounded by bare areas occur in semiarid landscapes. At one level, two phases of the mosaic are the banded vegetation-patches (vegetation arcs) and the bare areas, but at another level two phases can be distinguished inside the vegetation arc. One phase (frontal zone) is always in the upslope boundary of the arc, has only herbs and it has been suggested that it functions as a colonization area, while the other one (central zone) is at the middle of the arcs and has both shrubs and herbs. The demography of a tussock grass (Hilaria mutica) growing in the two phases of the vegetation arcs was studied under the hypothesis that it will show the demographic parameters of a ruderal species in the frontal zone and those of a more competitive species in the central zone. Temporal variability was assessed through annual, average, periodic and stochastic matrices. λ-values are higher in the frontal than in the central zone, and lower in dry years than in years with moderate precipitation. The influence of the demographic processes on λ-values shows spatial and temporal variation. In dry years, λ-values are more sensible to stasis (permanence in the same size class) and retrogression (transition to a smaller size class) in both zones, whereas in years of moderate precipitation the influence of fecundity and growth increases in the frontal zone and the influence of stasis and retrogression continue to be the most important in the central zone. Variations in the demographic parameters observed in the frontal zone are evidences of a life history plasticity finely tuned with environmental variation, and these results support the hypothesis that frontal zones function as colonization areas. This revised version was published online in June 2006 with corrections to the Cover Date.     

Morpho-Physiological Study of Ameboid Movement. 3. Invisible gel structures in the endoplasm of an ameba of the verrucosa type

SYNOPSIS. A small ameba of the verrucosa type has a flattened and fan-shaped body, at the broadest front of which there is formed a distinct hyaline zone. Along the lateral borders thereof there is a thin optically indistinct but rigid body wall, which can be determined by means of cine-micrographic analysis of the positions of granules in and near it, and their movements. Its caudal portion is well differentiated from the rest of the body and was identified as a region of complicated conditions, manifesting solating activity, contractility, ejection, formation of caudal pseudopods, and continuous shifting of its minute components. The tracks of moving endoplasmic granules were plotted to determine their individual irregularities in velocity and direction of movement. These tracks suggest the existence in the endoplasm of small to large motionless gel structures derived from the frontal hyaline zone, which is therefore postulated to be heterogeneously gelate as a whole. Judging from the fact that granules carried by the protoplasmic matrix passed through these so-called gel areas, it is proposed that the source of the motive force of ameboid movement may be in the advancing edge of the clear frontal zone where gelation is vigorously taking place.     

The fine structure of the newly discovered propodial ganglia of the veliger larva of the nudibranch Onchidoris bilamellata

Summary Two pairs of ganglia are found in the propodial region of the veliger of Onchidoris bilamellata: the anterolateral pair is located at the foremost corners of the propodium, and the frontal pair is located beside the propodial midline. Both sets of ganglia are positioned below the epidermis, and they are joined to the cerebral ganglia by large, common connectives. Each ganglion possesses sensory cells, nerve cells and sheath cells, and the frontal pair contains a complement of secretory cells. Externally, the propodial ganglia are manifested as sensory fields. The fields of the anterolateral pair are elliptical in shape, and each appears as a band of cilia bordering an unciliated zone. The region devoid of cilia is composed of ordinary epidermal cells, whereas the ciliated portion is comprised of dendritic endings originating from cells in the ganglion. Dendrites arise from one type of sensory cell and pass through the epidermis in bundles. Each dendrite terminates as a single cilium at the epidermal surface. Sensory fields of the frontal ganglia are key-shaped and oppose one another on the anterior end of the foot. Each field appears as a flat, circular, unciliated region which extends into a ciliated groove that runs dorsally toward the mouth. The groove contains the terminals of secretory cells, ciliated sensory cells, and the cell bodies of nonciliated sensory cells. The nonciliated sensory cells, characterized by a microvillous apex, are the dominant cells in the flattened circular zone. The space between the frontal ganglia and the epidermis is bridged by bundles of processes which are similar to those of the anterolateral ganglia. However, these tracts contain collections of the apical processes of secretory cells, the dendrites of ciliated sensory cells, and the axons of nonciliated sensory cells. Morphological and behavioral evidence indicates that the propodial ganglia serve a chemosensory function during settlement and metamorphosis.     

Low-Level Microwave Irradiations Affect Central Cholinergic Activity in the Rat

Sodium-dependent high-affinity choline uptake was measured in various regions of the brains of rats irradiated for 45 min with either pulsed or continuous-wave low-level microwaves (2,450 MHz; power density, 1 mW/cm2; average whole-body specific absorption rate, 0.6 W/kg). Pulsed microwave irradiation (2-microseconds pulses, 500 pulses/s) decreased choline uptake in the hippocampus and frontal cortex but had no significant effect on the hypothalamus, striatum, and inferior colliculus. Pretreatment with a narcotic antagonist (naloxone or naltrexone; 1 mg/kg i.p.) blocked the effect of pulsed microwaves on hippocampal choline uptake but did not significantly alter the effect on the frontal cortex. Irradiation with continuous-wave microwaves did not significantly affect choline uptake in the hippocampus, striatum, and hypothalamus but decreased the uptake in the frontal cortex. The effect on the frontal cortex was not altered by pretreatment with narcotic antagonist. These data suggest that exposure to low-level pulsed or continuous-wave microwaves leads to changes in cholinergic functions in the brain.     

The relationship between marine fronts and fish diversity in the Patagonian Shelf Large Marine Ecosystem

Aim To evaluate the relationship between marine fronts and (1) fish diversity patterns, (2) fish biomass distribution, and (3) fish assemblage structure. Location Patagonian Shelf, Southwestern Atlantic Ocean. Methods Three main frontal systems and eight nearby zones (frontal vs. non‐frontal areas) were compared. An extensive fishery database, obtained during an a priori sampling scheme (spatial resolution 1 × 1) from 1978 to 1979, was employed. Analyses of 248 trawling stations were performed using a combination of diversity measures (species richness, Shannon diversity and evenness), biomass analyses and multivariate analyses [nonparametric analysis of similarity (ANOSIM), non‐metric multidimensional scaling ordination (NMDS) and similarity percentages (SIMPER)] to evaluate the effect of fronts on fish communities. Results In total, 46 fish taxa were identified. Demersal fish diversity increased at the tidal front of Península Valdés but decreased in the frontal zones of the Southern Shelf‐Break and Magellan frontal systems. The richness and biomass of pelagic fish were higher at the Península Valdés Tidal Front, while the biomass of demersal fish was higher at its non‐frontal counterpart. Fish diversity did not differ consistently along the Northern Shelf‐Break Front. However, a higher fish biomass was registered at the non‐frontal zone. Demersal and pelagic fish assemblages differed between frontal and non‐frontal zones. Main conclusions The Patagonian Shelf Large Marine Ecosystem has diverse frontal types that appear to have different effects on fish diversity and assemblage structure. Seasonal (tidal) or permanent fronts have different effects on the parameters analysed, which could be due to productivity–diversity relationships. The Península Valdés Tidal Front, a relatively short temporal scale system, demonstrates a stronger influence on fish diversity, biomass and assemblage structure than the other frontal areas studied. The seasonality of nutrient input owing to frontogenesis, which begins during the austral spring, may play an important role in determining local diversity. At permanent frontal features, diversity decreases when the nutrient availability is high. This is potentially because, when food resources increase, a few species become dominant.     

Morphometric study on the interhemispheric asymmetries in the Wistar rat and the effects of early experience.

Sixty male Wistar rats were used for this experiment and assigned at random to the control group or to the stimulation method. Control rats show cerebral asymmetry with right bias at the frontal and occipital lobes. In the case of stimulated rats the differences from the occipital zone increase while those from the frontal lobe disappear.     

Brain Phospholipase A2 Is Activated After Experimental Closed Head Injury in the Rat

Head injury was induced in rats by a weight drop device, falling over the left hemisphere. The rats were killed at 15 min, 4 h, and 24 h after injury. Cortical slices were taken from the injured zone, from the corresponding region of the contralateral hemisphere, and from the frontal lobe of both hemispheres. These cortical slices were incubated in the presence of a fluorescent phospholipid analogue, 1-acyl-2-(N-4-nitrobenzo-2-oxa-1,3-diazole)aminocaproylphosphatidylch oli ne (C6-NBD-PC) which is a substrate for phospholipase A2 (PLA2) in intact cells. The interaction of this substrate with cells produces only one fluorescent product, the fatty acid C6-NBD-FA, released from the 2-position of C6-NBD-PC. Thus, the level of C6-NBD-FA produced is a direct measure of PLA2 activity. Fifteen minutes after trauma, a 75% increase of PLA2 activity was found in the injured zone. At 4 h, the frontal lobe of the contused, left hemisphere had elevated PLA2 activity, as well as the injured zone (92 and 81%, respectively). At 24 h, PLA2 activity at the site of injury was 245% of sham. In the right, noninjured zone, no significant changes in PLA2 activity were noticed during the entire time course of the experiment. Prostaglandin E2 (PGE2) was extracted from the same cortical slices as those used for PLA2 activity measurement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Testing steering functions of the frontal zone in the locomotion of amoeba proteus

Light and chemical stimuli were asymmetrically applied to the advancing front of amoeba without affecting any body region behind the frontal zone. Stimulation limited to the front alone was sufficient to control the frontal expansion and, as a further consequence, the locomotion and shape of the whole cell. Contracting factors applied locally to the front inhibited it, whereas the relaxing agents activated its expansion.     

Behavioral effects of thyrotropin releasing hormone in frontal decorticated rats

A low dose intracerebroventricular injection of thyrotropin releasing hormone (TRH, 100 ng) changed many behavioral responses in the rat. TRH increased locomotion, scratching, body shaking, piloerection, and rearing, but decreased sniffing, and resting. Ablation of frontal neocortex further enhanced the TRH effects on locomotion and resting. A dose effect of TRH (0, 5, 10, 50, 100 ng) to increase general activity was established and the effect was further enhanced by decortication. In our test situations decortication had no effect by itself. Since the TRH effects became much more pronounced without the frontal neocortex it appears that the cortex exerts a powerful inhibitory effect to moderate the TRH effects. The TRH effect does not depend upon the frontal cortex, actually a cortical function is to dampen the TRH effects on various behavioral responses.     

旅游活动对张家界国家森林公园土壤酶活性与微生物分布的影响

以张家界国家森林公园为例,分别设背景、缓冲和活动3个试验区,探讨了旅游活动对土壤理化性质、土壤酶活性和土壤微生物分布的影响.结果表明:土壤酶和土壤微生物的分布特征呈现背景区最高,活动区最低,缓冲区居中的变化规律;对土壤酶活性的影响在0～5 cm土层最为显著,其中纤维素酶活性在活动区分别比缓冲区和背景区降低了92.8%和80.0%;其次,旅游活动显著影响了0～5 cm土壤土层中的细菌、放线菌、真菌及总微生物数量,其中背景区明显高于缓冲区和活动区,缓冲区又明显高于活动区.旅游活动已对张家界国家森林公园土壤生态系统产生了较大影响.     

Separation of amino acids by simulated moving bed using competitive Langmuir isotherm

The separation of two amino acids, phenylalanine and tryptophan, was carried out using laboratory simulated moving bed (SMB) chromatography. The SMB process consisted of four zones, with each zone having 2 columns. The triangle theory was used to obtain the operating conditions for the SMB. The mass transfer coefficients of the two amino acids were obtained from the best-fit values by comparing simulated and experimental pulse data. The competitive adsorption isotherms of the two amino acids were obtained by single and binary frontal analyses, taking into consideration the competition between the two components. A competitive Langmuir isotherm, obtained from single-component frontal chromatography, was used in the first run, and the isotherm from binary frontal chromatography in the second, with the flow rate of zone I modified to improve the purity. Compared to the first and second runs, the competitive Langmuir isotherm from the binary frontal chromatography showed good agreement with the experimental results. Also, adjusting the flow rate in zone I increased the purity of the products. The purities of the phenylalanine in the raffinate and the tryptophan in the extract were 99.84 and 99.99%, respectively.     

Different receptor subtypes are involved in the serotonin-induced modulation of epileptiform activity in rat frontal cortex in vitro.

The frontal cortex is innervated by serotonergic terminals from the raphe nuclei and it expresses diverse 5-HT receptor subtypes. We investigated the effects of 5-HT and different 5-HT receptor subtype-selective agonists on spontaneous discharges which had developed in rat cortical slices perfused with a Mg2+-free medium and the GABA(A) receptor antagonist picrotoxin. The frequency of synchronous discharges, recorded extracellularly in superficial layers (II/III) of the frontal cortex, was dose-dependently enhanced by 5-HT (2.5-40 microM). That excitatory effect was blocked by the 5-HT2 receptor selective antagonist ketanserin. The 5-HT2A/2C receptor-selective agonist DOI and the 5-HT4 receptor agonist zacopride also increased the frequency of spontaneous discharges. In the presence of ketanserin, 5-HT decreased the discharge rate; a similar effect was observed when the 5-HT1A receptor agonist 8-OH-DPAT or the 5-HT1B receptor agonist CGS-12066B was applied. The 5-HT3 receptor agonist m-CPBG was ineffective. In conclusion, 5-HT produces multiple effects on epileptiform activity in the frontal cortex via activation of various 5-HT receptor subtypes. The excitatory action of 5-HT, which predominates, is mediated mainly by 5-HT2 receptors. The inhibitory effects can be attributed to activation of 5-HT1A and 5-HT1B receptors.     

Intercentral interactions in the neocortex of 2-year-old children when exposed to verbal signals

It has been shown by the EEG correlation analysis method that perception by children of the third year of life of signal verbal stimuli consderably increases spatial synchronization of biopotentials as compared with the action of indifferent verbal stimuli. Perception and recognition of words is attended with involvement in the synchronous activity of potentials of the inferior parietal and frontal associative zones and the projection zone of the auditory analyser in the left hemisphere. In addition, children of the indicated age, as compared with a younger age, display an involvement in the sensory analysis of a word of the projection zones of the articulation apparatus, which establish an interconnection with the frontal zones of the dominant hemisphere.     

Neonatal cerebral cortical lesion abolishes the anxiolytic action of diazepam in adult rats: effects of location and extent of cortical lesion.

In our previous study, diazepam (DZP), a benzodiazepine receptor agonist, failed to suppress foot-shock-elicited ultrasonic vocalizations (USVs) in adult rats that had been neonatally lesioned in the neocortex. Because neonatal lesion of the neocortex did not influence the production of USVs, the presence of an anxiolytic mechanism of DZP is suggested apart from any anxiogenic mechanism in the brain. However, the previous study did not indicate any specific cortical regional lesions that impaired the normal development of the anxiolytic mechanism in the brain. The present study was undertaken in order to examine whether neonatal lesion of the neocortex, smaller and more localized than that in the previous study, abolishes the anxiolytic effect of DZP on foot-shock-elicited and air-puff-elicited USVs. A neonatal lesion about 2 mm diameter was made in the unilateral frontal cortex frontal to the hindlimb area or in the occipital cortex caudal to the hindlimb area. The attenuating effect of DZP on the USVs elicited by both aversive stimuli was found to be abolished only in the frontal cortex-lesioned rats. This finding indicates that the frontal cortex is likely to be specifically involved in the normal development of the benzodiazepine-anxiolytic mechanism in the brain.