A simple regression model to assess environmental effects on fish growth

Multiple regression was used to assess relationships between annular growth and environmental variables. This approach (1) tests for the significance of environmental changes on fish growth and (2) can be successfully used to predict fish growth using different environmental conditions. Age usually explains a large proportion of the variation in growth increments measured in length, and these two variables are inversely related. Since length increments decline as age increases, environmental impacts on growth will be reduced as fish grow older. To account for within-age growth variation and incorporate this age-dependent factor, the inverse of age (1/age in years) is multiplied by the value of an environmental variable (ENV) that may be related to growth. This interaction term and age are regressed against mean annular growth increments in length (TLINC; l _{t +1}— l ₁):
TLINC = b₀—b₁AGE±b₂(1/AGE)*ENV
where b₀, b₁, and b₂ are the regression coefficients for intercept and slope, respectively. Additional variables that measure environmental factors can be added to the model. Environmental effects associated with growth rates of black crappie, Pomoxis nigromaculatus (LeSueur), are presented as an example.     

Age, growth and reproduction of the barrelfish Hyperoglyphe perciformis (Mitchill) in the western North Atlantic

Otoliths ( n = 847) and gonads ( n = 817) were collected from barrelfish Hyperoglyphe perciformis that were captured by commercial fishermen in the waters off South Carolina and Georgia in 1995, 1997 and 2001–2006. Of the otoliths collected, 97% were aged successfully, and specimens sampled ranged from 5 to 85 years, with a median age of 12 years. The von Bertalanffy growth parameters yielded the equation: L_t = 857·8{1 − e^{−0·0985[ t −(−8·95)]}}, where L_t is fork length ( L _F) at time t . Through histological examination, 94% of the gonads assessed were assigned to a sex and reproductive class. Females spawned from September to May with a peak from November to January. Males spawned year round, but had a peak from September to April. The sex ratio (M:F) for this population was 1:1·34. The smallest mature female was 605 mm L _F and the youngest immature female was 697 mm L _F. Estimates of L _F and age at 50% maturity ( L ₅₀ and A ₅₀) for females were 660 mm L _F (95% CI = 633–667 mm L _F) and 6·08 years (95% CI = 3·50–7·27 years), respectively. The youngest mature male was 575 mm L _F and the oldest immature male was 762 mm L _F, and no estimates of L ₅₀ or A ₅₀ were made for males. It was determined that barrelfish exhibit the typical characteristics of long life span, slow growth and high age at maturity seen in other deepwater fishes, and that care should be taken to manage this species accordingly.     

Mackerel icefish size and age differences and long‐term change at South Georgia and Shag Rocks

This study analysed the total length ( L _T)‐frequency distribution of mackerel icefish Champsocephalus gunnari at South Georgia and Shag Rocks from nine bottom trawl surveys at South Georgia and eight at Shag Rocks between 1987 and 2002. The estimated mean L _T of age‐classes 1+, 2+, 3+ and 4+ years during January were, respectively, 14·7, 23·5, 29·8 and 35·1 cm at South Georgia. Age‐classes 1+, 2+ and 3+ years were 18·3, 26·2 and 33·8 cm at Shag Rocks. The derived Bertalanffy growth parameters for South Georgia were: L _∞ = 51·7 cm, k  = 0·27 and t ₀ = −0·26. The mean L _T of each age‐class of C. gunnari at Shag Rocks was significantly larger than at South Georgia, equivalent to c . 5 months growth, although the annual growth in L _T was similar. This is further evidence that C. gunnari hatched earlier at Shag Rocks. At South Georgia, the mean L _T of age‐classes 1+ and 3+ years were correlated, and significantly decreased between 1987 and 2002, and were smaller following warmer summers. This decrease in the size of C. gunnari may be the result of reduced food availability linked to climate warming.     

Effects of river flow on larval growth and survival of Japanese seaperch Lateolabrax japonicus (Pisces) in the Chikugo River estuary, upper Ariake Bay

The abundance and growth history of larval and juvenile Japanese seaperch Lateolabrax japonicus were investigated in the Chikugo River estuary, upper Ariake Bay, from 1990 to 2000. Growth during the larval period (up to 15 mm standard length, L _S, the size at recruitment into the estuary) was backcalculated using sagittal otolith microstructures by the biological intercept method. Growth rates in length declined at body sizes >14 mm L _S. High freshwater discharge through the Chikugo River was associated with high temperatures of the upper Ariake Bay where the larvae spend their planktonic life. Mean larval stage duration (days) from hatch to 15 mm ( D ₁₅) varied between 48·8 and 76·2 days and was inversely correlated with the estimated mean temperature history [mean daily temperature (° C) experienced by the larvae during the period from hatch to 15 mm, T ₁₅]. Mean abundance (number m⁻²) of larvae and juveniles was highest in years when T ₁₅, D ₁₅ and freshwater discharge were at intermediate levels. Although the abundance was not correlated with either of these variables, an exponential relationship between abundance and D ₁₅ was found when data collected during the highest river discharge years (1990, 1991 and 1998) were excluded. The increase in freshwater discharge through the Chikugo River probably had the potential to enhance or diminish Japanese seaperch recruitment in two ways: 1) it could increase recruitment probability by increasing temperature and larval growth and 2) high river flow also had the potential to decrease the probability of immigration into the river by increasing larval seaward dispersion, predation due to decreased turbidity and starvation due to decreased zooplankton prey abundance in the estuary.     

Competitive Inhibition of Rat Brain Hexokinase by 2-Deoxyglucose, Glucosamine, and Metrizamide

Abstract: The effects of metrizamide on the kinetics of rat brain hexokinase were compared in vitro with those of 2-deoxyglucose and glucosamine. Although metrizamide, 2-deoxyglucose, and glucosamine are known to be competitive inhibitors of approximately equal potency for glucose of yeast hexokinase ( K ₁ approximately 0.7 m m for all three), metrizamide is a much weaker competitive inhibitor ( K _i about 20 m m ) of rat brain hexokinase than either 2-deoxyglucose or glucosamine ( K _i about 0.3 m m for both). This indicates a greater active site specificity of rat brain hexokinase than of yeast hexokinase. Rat brain hexokinase activity is enhanced approximately threefold in the presence of 0.05, 0.2, and 0.8 mg/ml bovine serum albumin, while yeast hexokinase is only enhanced by 50% under these conditions. Despite the high K _i value for metrizamide, interference with glucose metabolism may occur whenever metrizamide is present in much higher concentrations than glucose. Myelography in humans is one such situation.     

The self-incompatibility response in Papaver rhoeas is mediated by cytosolic free calcium

The role of Ca²⁺ signalling during the self-incompatibility (SI) response in Papaver rhoeas L. has been investigated using Ca²⁺-sensitive dyes. Pollen tubes were micro-injected with Calcium Green-1 and cytosolic free calcium ([Ca²⁺]_i) imaged using laser scanning confocal microscopy (LSCM). Addition of incompatible stigmatic S-glycoproteins induced a transient increase in the level of [Ca²⁺]_i in pollen tubes. In contrast, no rise in [Ca²⁺]_i was detectable after addition of either compatible or heat-denatured incompatible stigmatic S-glycoproteins. The elevation of [Ca²⁺]_i was followed by the specific inhibition of pollen tube growth in incompatible reactions. It has been shown previously that gene expression in pollen tubes is switched on during an incompatible reaction. Since the [Ca²⁺]_i transient appeared to originate from the region where the nuclei are located, Ca²⁺ may be involved in locally regulating the expression of these genes. The photoactivation of caged Ca²⁺ to artificially elevate [Ca²⁺]_i resulted in the inhibition of pollen tube growth and thus mimicked the SI response. Taken together, the results provide an important link between a transient rise in [Ca²⁺]_i and the biological phenomenon of inhibition of pollen tube growth and demonstrate, for the first time, direct evidence that the SI response in P. rhoeas is mediated by [Ca²⁺]_i.     

Carbon dioxide induces increases in guard cell cytosolic free calcium

The hypothesis that increases in cytosolic free calcium ([Ca²⁺]_i) are a component of the CO₂ signal transduction pathway in stomatal guard cells of Commelina communis has been investigated. This hypothesis was tested using fura-2 fluorescence ratio photometry to measure changes in guard cell [Ca²⁺]_i in response to challenge with 700 µl l⁻¹ CO₂. Elevated CO₂ induced increases in guard cell [Ca²⁺]_i which were similar to those previously reported in response to abscisic acid. [Ca²⁺]_i returned to resting values following removal of the CO₂ and further application of CO₂ resulted in a second increase in [Ca²⁺]_i. This demonstrated that the CO₂-induced increases in [Ca²⁺]_i were stimulus dependent. Removal of extracellular calcium both prevented the CO₂-induced increase in [Ca²⁺]_i and inhibited the associated reduction in stomatal aperture. These data suggest that Ca²⁺ acts as a second messenger in the CO₂ signal transduction pathway and that an increase in [Ca²⁺]_i may be a requirement for the stomatal response to CO₂.     

Overexpression of δ-Opioid Receptors in Recombinant Baculovirus-Infected Trichoplusia ni"High 5" Insect Cells

Abstract: "High 5" cells derived from Trichoplusia ni ovaries were infected with baculovirus bearing the cDNA of the mouse δ-opioid receptor. The maximal binding capacity for the narcotic antagonist [³H]naltrindole was 1.4 pmol/mg of membrane protein, and that for the agonist [³H][ d -penicillamine², d -penicillamine⁵]enkephalin (DPDPE) was 0.3 pmol/mg. DPDPE proved highly potent in competing with its tritiated analogue at δ-receptors of NG108-15 hybrid cells and of High 5 and Sf9 insect cells. However, in insect cells the opioid was more than 100-fold less effective in competing with [³H]naltrindole as compared with the mammalian cells. This decline in potency was counteracted in a dose-dependent manner by exposure of High 5 membranes to the exogenous G protein G_o, which increased the binding capacity for DPDPE. Functional studies revealed a dose-dependent inhibition (up to 30%) by opioids on forskolin-stimulated cyclic AMP synthesis, and this effect was potentiated by G_o. Quantification of Gα_o and Gα_i disclosed striking differences between Sf9 and High 5 insect cells, both of which overexpressed the cloned δ-opioid receptor. Although no inhibitory G proteins were detected in membranes of Sf9 cells, High 5 cells contained 0.5 pmol of Gα_o/mg of membrane protein, and a 20-fold higher concentration for Gα_i. The distinct G-protein expression in insect cells may be considered an advantage for studying functions of G protein-coupled receptors.     

Photosystem II inhibition by moderate light under low temperature in intact leaves of chilling-sensitive and -tolerant plants

Photosystem II (PSII) activity was examsined in leaves of chilling-sensitive cucumber ( Cucumis sativus L.), tomato ( Lycopersicum esculentum L.), and maize ( Zea mays L.), and in chilling-tolerant barley ( Hordeum vulgare L.) illuminated with moderate white light (300 µmol m⁻² s⁻¹) at 4°C using chlorophyll a fluorescence measurements. PSII activity was inhibited in leaves of all the four plants as suggested by the decline in F _v/ F _m, 1/ F _o − 1/ F _m, and F _v/ F _o values. The changes in initial fluorescence level ( F _o), F _v/ F _m, 1/ F _o − /1/ F _m, and F _v/ F _o ratios indicate a stronger PSII inhibition in cucumber, maize and tomato plants. The kinetics of chlorophyll a fluorescence rise showed complex changes in the magnitudes and rise of O-J, J-I, and I-P phases caused by photoinhibition. The selective suppression of the J-I phase of fluorescence rise kinetics provides evidence for weakened electron donation from the oxidizing side, whereas the accumulation of reduced Q_A suggests damage to the acceptor side of PSII. These findings imply that the process of chilling-induced photoinhibition involves damage to more than one site in the PSII complexes. Furthermore, comparative analyses of the decline in F _v/ F _o and photooxidation of P700 explicitly show that the extent of photoinhibitory damage to PSII and photosystem I is similar in leaves of cucumber plants grown at a low irradiance level.     

Temperature responses are a window to the physiology of dark respiration: differences between CO2 release and O2 reduction shed light on energy conservation

We showed that temperature responses of dark respiration for foliage of Pinus radiata could be approximated by Arrhenius kinetics, whereby E ₀ determines shape of the exponential response and denotes overall activation energy of respiratory metabolism. Reproducible and predictable deviation from strict Arrhenius kinetics depended on foliage age, and differed between R _CO2 and R _O2. Inhibition of oxygen reduction ( R _O2) by cyanide (inhibiting COX) or SHAM (inhibiting AOX) resulted in reproducible changes of the temperature sensitivity for R _O2, but did not affect R _CO2. Enthalpic growth – preservation of electrons in anabolic products – could be approximated with knowledge of four variables: activation energies ( E ₀) for both R _CO2 and R _O2, and basal rates of respiration at a low reference temperature ( R _REF). Rates of enthalpic growth by P. radiata needles were large in spring due to differences between R _REF of oxidative decarboxylation and that of oxygen reduction, while overall activation energies for the two processes were similar. Later during needle development, enthalpic growth was dependent on differences between E ₀ for R _CO2 as compared with R _O2, and increased E ₀( R _O2) indicated greater contributions of cytochrome oxidase to accompany the switch from carbohydrate sink to source. Temperature-dependent increments in stored energy can be calculated as the difference between R _CO2▵ H _CO2 and R _O2▵ H _O2.     

Regional differences in length at sexual maturity for female blue whales based on recovered Soviet whaling data

New blue whale ovarian corpora data from illegal Soviet catches in the Southern Hemisphere and northern Indian Ocean were recovered from the original logbooks. Catches north of 52°S were assumed to be pygmy blue whales ( Balaenoptera musculus brevicauda , n = 1,272); those south of 56°S were assumed to be Antarctic (true) blue whales ( B. m. intermedia , n = 153). Three probable Antarctic blue whales north of 52°S were excluded. Lengths at which 50% and 95% of females become sexually mature ( L ₅₀ and L ₉₅) were estimated from a Bayesian logistic model. These estimates are more precise than previous Japanese estimates because Soviet catches below the legal minimum of 70 ft (21.3 m) were 32 times greater. For pygmy blue whales L ₅₀ was 19.2 m (95% interval 19.1–19.3 m) and L ₉₅ was 20.5 m (95% interval 20.4–20.7 m). Antarctic L ₅₀ (23.4 m, 95% interval 22.9–23.9 m) was much longer than L ₅₀ for pygmy blue whale regions (18.4–19.9 m). The median L ₅₀ for the northern Indian Ocean was 0.5–0.6 m shorter than for pygmy blue whales from other regions; although statistically significant, these small length differences provide little support for northern Indian Ocean blue whales being a separate subspecies, B. m. indica .     

Recombinant stigmatic self-incompatibility (S-) protein elicits a Ca2+ transient in pollen of Papaver rhoeas

Evidence for Ca²⁺ signalling in pollen during the self-incompatibility (SI) response in Papaver rhoeas L. has been presented previously. However, it was not known whether the S-protein alone could act as an elicitor of the response or whether the presence of other stigmatic components was required, since relatively crude stigmatic extracts had been used. The S ₁ gene has since been cloned and its product expressed in Escherichia coli has been shown to exhibit biological activity. In this paper it is reported that the recombinant protein (S₁e) elicits a transient rise in [Ca²⁺]_i in incompatible pollen. The Ca²⁺ signal appears indistinguishable from that elicited by S-gene products partially purified from plant extracts in terms of both its timing and spatial distribution. Pollen tube growth is arrested directly after the rise in [Ca²⁺]_i.
The results provide direct evidence that the S-protein alone acts as an elicitor which triggers the Ca²⁺ signal for the pollen SI response. In addition, it is now clear that the recombinant S-protein does not require several post-translational processing events which take place in the plant to act as an elicitor. With respect to the spatial distribution of the Ca²⁺ transient, data are presented which correlate the localized rise in intracellular Ca²⁺ ([Ca²⁺]_i) with the 'nuclear complex' and the endoplasmic reticulum which is associated with this region.     

Effects of sulfate and nitrate on K+ uptake and growth of wheat and cucumber

The uptake of K⁺ ion was studied in the roots of wheat ( Triuicum aestivum L. cv. GK Szeged) and cucumber ( Cucumis sativus L. cv. Budai csemege) seedlings grown in nutrient solution under nitrogen and sulfate stress conditions. Seedlings pretreated with 1 or 10 m M NaNO₃, absorbed more K⁺ than those treated with 0.1 m M NaNO₃. However, the posteffect of NaNO₃ was considerably influenced by the Na₂SO₄, treatment. The results suggest that, at least partly, a feed-back regulation of K⁺ uptake may occur. However, due to the high Na⁺ contents of the roots, a Na⁺ effect in this process cannot be excluded. The growth and dry matter yields of the roots and shoots were strongly influenced by the SO²⁻/₄ and NO⁻/₃ supply of the plants. Appreciable differences were experienced between wheat and cucumber seedlings. The optimum SO²⁻/₄ concentration of the growth solution for maximal growth varied considerably between the species, and was also different for the roots and the shoots in a given species.     

Nerve Growth Factor, Epidermal Growth Factor, and Insulin Differentially Potentiate ATP-Induced [Ca2+]i Rise and Dopamine Secretion in PC12 Cells

Abstract: To study how growth factors affect stimulus-secretion coupling pathways, we examined the effects of nerve growth factor (NGF), epidermal growth factor (EGF), and insulin on ATP-induced [Ca²⁺]_i rise and dopamine secretion in PC12 cells. After a 4-day incubation of cells, all three factors increased ATP-induced dopamine secretion significantly. We then examined which step of ATP-induced secretion was affected by the growth factors. Cellular levels of dopamine-β-hydroxylase and catecholamines were increased by NGF treatment but were not affected by EGF or insulin. The ATP-induced [Ca²⁺]_i rise was also enhanced after growth factor treatment. The EC₅₀ of ATP for inducing [Ca²⁺]_i rise and dopamine secretion was increased by NGF treatment but not by treatment with EGF or insulin. Accordingly, the dependence on [Ca²⁺]_i of dopamine secretion was increased significantly only in NGF-treated cells. Our results suggest that for EGF- and insulin-treated PC12 cells, the increase in secretion is mainly due to increased potency of ATP in inducing [Ca²⁺]_i rise. NGF treatment not only increased the potency of ATP but also decreased the Ca²⁺ sensitivity of the secretory pathway, which as a result becomes more tightly regulated by changes in [Ca²⁺]_i.     

Age, growth and mortality of picarel, Spicara smaris L. (Pisces: Centracanthidae), from the eastern Adriatic (Croatian coast)

Age, growth and mortality of picarel Spicara smaris L. collected in the eastern middle Adriatic during April and May in 1999 were studied. The total lengths of individuals ranged from 6.3 to 19.8 cm, and the weight from 2.2 to 78.3 g. The slopes ( b values) of the total length–weight regressions indicated negative allometric growth for females ( b =2.8± 0.03) and isometric growth for males ( b =3.08±0.04). The oldest female and male were 4 and 6 years, respectively. The von Bertalanffy growth parameters for the sexes combined were ( L _∞=22.76 cm, K =0.277, t ₀=−0.793). The overall sex ratio was 1 : 4.1 in favour of females. Individuals larger than 17.9 cm were all males.     

The cytochrome bd terminal oxidase of Azotobacter vinelandii: Low temperature photodissociation spectrophotometry reveals reactivity of cytochromes b595 and d with both carbon monoxide and oxygen

Abstract Cytochromes d and b ₅₉₅ were studied by low temperature photodissociation of CO-ligated Azotobacter vinelandii membranes. White light or He-Ne laser irradiation revealed 436 and 594–597 nm absorption bands to be due to Fe¹¹ cytochrome b ₅₉₅. Oxy-cytochrome d (648 nm) was formed when the CO adduct was photolysed in the presence of oxygen. This was followed by ligand recombination (presumably oxygen) to the high-spin cytochrome b ₅₉₅, with a distinctive shift to shorter wavelengths of the α-band of the cytochrome, and a decrease in the oxygenated form. All spectral changes were light-reversible. We demonstrate the light-reversible binding of CO to both cytochromes b ₅₉₅ and d , and suggest migration of oxygen from cytochrome d to cytochrome b ₅₉₅ at a haem-haem binuclear centre during the oxidase reaction.     

Lifetime consequences of variable 0 year group length in riverine populations of chub Leuciscus cephalus (L.)

The fork length ( L _F) of individual chub Leuciscus cephalus in English riverine populations at the end of their first growth season varied considerably, ranging from <25 to >70 mm. This had a significant influence on the subsequent growth of individuals over their lifetime. Chub of small L _F at age 1 year generally produced smaller annual growth increments throughout life than those of longer L _F at age 1 year, although they had the potential to attain greater ultimate L _F. This variability in L _F at age 1 year resulted, at least in part, from multiple spawning events over a protracted period, that caused variation in the growing seasons for 0 year group chub of the same year class. Since the adult population contained individuals that only attained L _F of <25 mm at the end of their first growing season, it is possible that L _F at age 1 year may not be such a major precursor to strong chub recruitment as previously thought.     

Nitric Oxide Disrupts Ca2+ Homeostasis in Hippocampal Neurons

Abstract: Nitric oxide has been recognized in recent years as an important mediator of neuronal toxicity, which in many cases involves alterations of the cytoplasmic Ca²⁺ concentration ([Ca²⁺]_i). In [Ca²⁺]_i fluorimetric experiments on cultured hippocampal neurons, the nitric oxide-releasing agent S -nitrosocysteine produced a delayed rise in [Ca²⁺]_i over a 20-min exposure, which was accompanied by a progressive slowing of the kinetics of recovery from depolarization-induced [Ca²⁺]_i transients. These effects were blocked by oxyhemoglobin and by superoxide dismutase, confirming nitric oxide as the responsible agent, and suggesting that they involved peroxynitrite formation. Similar alterations of [Ca²⁺]_i homeostasis were produced by the mitochondrial ATP synthase inhibitor oligomycin, and when an ATP-regenerating system was supplied via the patch pipette in combined whole-cell patch-clamp-[Ca²⁺]_i fluorimetry experiments, S -nitrosocysteine had no effect on the resting [Ca²⁺]_i or on the recovery kinetics of [Ca²⁺]_i transients induced by direct depolarization. We conclude that prolonged exposure to nitric oxide disrupts [Ca²⁺]_i homeostasis in hippocampal neurons by impairing Ca²⁺ removal from the cytoplasm, possibly as a result of ATP depletion. The resulting persistent alterations in [Ca²⁺]_i may contribute to the delayed neurotoxicity of nitric oxide.     

Differences in size and growth rates of male and female migrating Japanese eels in Pearl River, China

The Sr/Ca ratios in otoliths of silver Japanese eels Anguilla japonica , in Pearl River, China, indicated that both sexes did not stay in brackish water and grew in fresh water from the glass eel stage until spawning migration. This did not support the hypothesis that females tended to distribute upstream and males might be restricted to estuaries. The back-calculated total length of males at glass eel stage was not significantly different from that of females, indicating that the hypothesis that small glass eels became males and larger ones became females may not be true. The mean (±S.D.) age and total length of males at migration were 6·4±1·6 years and 48·3±4·5 cm, which were significantly smaller than for females, 8·3±1·6 years and 61·4±4·1 cm. The age of migration was related inversely to growth rate for both sexes. Growth parameters of the von Bertalanffy growth equation were K =0·21 cm year°1, L _∞=55·7 cm and t _o=-0·55 year for males and K =0·14 cm year⁻¹, L _∞=77·5 cm and t _o=-0·60 year for females. The difference in asymptotic length ( L _∞) between males and females may be because females postpone migration to achieve larger size for maximizing reproductive success.