Temperature control on the post-embryonic growth of Neomysis intermedia Czerniawsky in a hypereutrophic temperate lake

In situ growth of Neomysis intermedia Czerniawsky at the post-embryonicstage was studied by the cohort analysis using the probabilitygraphic technique in a hypereutrophic temperate lake, Lake Kasumigaura.Two overwintering populations and 5 spring cohorts were recognizedover 2-yr field observations performed at 4–15 day intervals.There was no luck in order to follow possible cohorts in mid-summerand autumn. The specific growth rate of the post-embryonic stagedetermined varied between 0.001 and 0.16 (day ^–1) dependingupon the surrounding water temperature, and each individualgrowth showed an almost exponential pattern. Average size ofnew born individuals was {small tilde}2.1 mm in body lengthand was consistent regardless of the difference of seasons,but the average mature size was highly temperature dependent,ranging between 7.6 and 12.0 mm for males and 8.1 and 13.5 mmfor females.     

Use of15N/14N rations to evaluate the food source of the mysid,Neomysis intermedia Czerniawsky,in a eutrophic lake in Japan

The stable isotope ratios of nitrogen were measured in the mysid,Neomysis intermedia, together with various biogenic materials in a eutrophic lake, Lake Kasumigaura, in Japan throughout a year of 1984/85. The mysid, particulate organic matter (POM, mostly phytoplankton), and zooplankton showed a clear seasonal change in ¹⁵N with high values in spring and fall, but the surface bottom mud did not. A year to year variation as well as seasonal change in ¹⁵N was found in the mysid. The annual averages of ¹⁵N of each material collected in 1984/85 are as follows: surface bottom mud, 6.3 (range: 5.7–6.9); POM, 7.9 (5.8–11.8); large sized mysid, 11.6 (7.7–14.3); zooplankton, 12.5 (10.0–16.4); prawn, 13.2 (9.9–15.4); goby, 15.1 (13.8–16.7). The degree of¹⁵N enrichment by the mysid was determined as 3.2 by the laboratory rearing experiments. The apparent parallel relationship between the POM and the mysid in the temporal patterns of ¹⁵N with about 3 difference suggests the POM (mostly phytoplankton) as a possible food source ofN. intermedia in this lake through the year.     

The effect of temperature on the post-embryonic growth of Neomysis intermedia Czernlawsky (Crustacea, Mysidacea) under laboratory conditions

The effect of temperature on post-embryonic growth of Neomysisintermedia was investigated under unlimited food conditionsin the laboratory. The effect of temperature on the size ofnewly released animals was negligibly small, but body size wasinversely related to temperature in adults. This was mainlycaused by the difference in the number of molts before maturation.The specific growth rate of N. intermedia increased exponentiallywith a temperature coefficient, Q₁₀ of 4.6 from 0.018 d^–13C to 0.21 d^–1 at 20C in juveniles, and with a temperaturecoefficient of 2.7 from 0.006 d^–1 at 3C to 0.05 d^–1at 25C in adults. The rate in juveniles levelled off above20C, and dropped at 29C. Brood size and brood interval decreasedwith temperature increase, while the daily specific reproductionrate increased. The specific growth rate of gravid females,including production of egg matter, increased exponentiallywith a temperature coefficient of 3.3 from 0.015 d^–1 at10C to 0.093 d^–1 at 25C. The present laboratory experiments confirmed the temperaturecontrol on the growth of N. intermedia suggested in a hyper-eutrophiclake.     

Intersexuality in the mysid Neomysis integer

Intersexuality is described in Neomysis integer (Leach), apparently the first occurrence among the Mysidacea. Seven out of 13,700 specimens examined were masculinized females possessing elongated fourth pleopods, a male secondary sexual characteristic. Each masculinized female appeared to have reproduced as a normal female; there was no evidence of testicular tissue.     

Assessment of the potential impact of the mysid shrimp, Neomysis mercedis, on Daphnia

Neomysis mercedis, an important invertebrate predator in somelakes and estuaries in North America, occurred at high densities(>2 mysids m^-3) in Lake Washington in the early 1960s, aperiod when Daphnia were scarce in the lake. Because Neomysisfeed selectively on Daphnia, it was hypothesized that mysidpredation contributed significantly to the scarcity of Daphnia.To evaluate this hypothesis, mysid abundance was monitored inthe lake (July 1989–February 1992), and whole lake predationimpacts on Daphnia were estimated. Mysid abundance varied from319 million, 0.1 mysids m^-3 (February 1992) to 4276 million,1.7 mysids m^-3 ( June 1991), and mysid biomass ranged from 1153(October 1991) to 4700 kg dry weight (November 1990). A peakin Daphnia consumption was noted during autumn, when total mysidbiomass was high. In late autumn/winter mysid consumption month^-1accounted for 28–95% of Daphnia biomass and 13–38%of production. Mysid densities in this study were 18x and 5xlower than in 1962 and 1975, respectively. By extrapolation,at a density of 3.5 mysids m^-3 observed in the early 1960s,total Neomysis consumption demand month^-1 exceeded 100% of Daphniabiomass (late autumn–early spring), and 100% of Daphniaproduction (late autumn–winter). Estimates of the totalmysid consumption demand in this study are thus in accord withthe hypothesis that Neomysis could control Daphnia abundancein Lake Washington.     

Predation by longfin smelt ( Spirinchus thaleichthys ) on the mysid Neomysis mercedis in Lake Washington

1. Longfin smelt and mysid samples collected in Lake Washington from 1988 to 1992 were examined, and historic data on smelt and mysid abundance were reviewed to assess the impacts of smelt predation on Neomysis mercedis. The feeding habits of smelt were also examined for differences between odd and even years, and seasonal and ontogenetic variations in smelt diet were described. 2. A reciprocal relationship in the abundance of 1+ smelt and Neomysis suggested that smelt regulate mysid abundance in the lake. 3. The proportion of smelt diet contributed by mysids was higher for less abundant year classes of smelt. 4. These results indicate that intraspecific competition for scarce mysids occurs in the even-year classes of smelt.     

Purification and characterization of vitellin from the estuarine mysid Neomysis integer (Crustacea; Mysidacea)

Invertebrates account for roughly 95% of all animals, yet surprisingly, little effort has been invested to understand their value in signaling potential environmental endocrine disruption. There has been, however, much recent attention on vitellogenin induction in egg-laying invertebrates and vertebrates as indicators of exposure to estrogenic xenobiotics. Mysid shrimp (Crustacea: Mysidacea) have been put forward by several researchers and regulatory bodies (e.g., US-EPA) as suitable test organisms for the evaluation of environmental endocrine disruption. In view of developing sensitive assays to study endocrine disruption in the estuarine mysid Neomysis integer, we isolated and characterized vitellin, the major yolk protein in eggs. Vitellin was purified using gel filtration and characterized by electrophoresis using different staining procedures. Specific (as shown by Western blotting) polyclonal antibodies were produced in rabbit against the purified vitellin of N. integer. These antisera will be used to develop immunoassays to study vitellogenesis in mysids and to detect potential stimulatory or inhibitory effects of endocrine disruptors on the production of vitellin.     

The taxonomic status of Western Pacific mysid species of Neomysis awatschensis (Brandt, 1851) group

The discussion of the taxonomic status of West Pacific mysid species Neomysis awatschensis (Brandt, 1851), N. intermedia (Czerniavsky, 1882) and N. nigra Nakazawa, 1910 has continued over the last century. Examination of a large taxonomic collection of the Zoological Institute of the Russian Academy of Sciences, including syntypes of N. awatschensis and N. intermedia, revealed that N. intermedia is a junior synonym of N. awatschensis and N. nigra is a valid species, not a synonym of N. awatschensis. N. nigra was first recorded in Russian waters in the Possyet Bay (Sea of Japan).     

Fine structure of the statocyst sensilla of the mysid shrimp Neomysis integer (Leach, 1814) (Crustacea,Mysidacea)

The fine structure of the statocyst sensilla of Neomysis integer was investigated. The statocyst contains about 35 sensilla, which are composed of two bipolar sensory cells, nine enveloping cells, and a seta. The sensory cells consist of an axon, a perikaryon, and a dendrite. The dendrite contains a proximal segment with a ciliary rootlet and at least one basal body, and a distal segment with a ciliary axoneme (9 × 2 + 0) at its base. The distal segment extends along the peripheral wall of the seta and is in close contact with the wall of the hair shaft. The enveloping cells surround the proximal and distal segments of the dendrite. The innermost enveloping cell contains a scolopale rod. It surrounds the receptor lymph cavity and secretes flocculent material into this cavity. From the tip of the cell a dendritic sheath, which encloses the distal segment of the dendrite, emerges. A peculiar feature of the second enveloping cell is the presence of a scolopale-like rod, which is more slender and less pronounced than in the first enveloping cell. The seta consists of three parts: a socket, a tubular midpart, and a gutter-like apical part, the tip of which penetrates into the statolith. The seta shows over its full length a bilaterally symmetrical axis that is coplanar with the plane in which the seta is bent toward the statolith. The structure of the seta and the position of the distal segments provide morphological evidence for directional sensitivity of the sensilla and for the magnitude of shear on the setal wall being an adequate stimulus.     

Morphogenesis during molting of the setae in the statocyst sensilla of the mysid shrimp Neomysis integer (Leach, 1814) (crustacea,mysidacea)

The morphogenesis of the setae in the statocyst sensilla of Neomysis integer was studied. Immediately before ecdysis, a new seta lies inverted between the enveloping cells. All of the nine enveloping cells, except the first one, secrete a well defined part of the new seta. The second, third, fourth, and fifth have a trichogen function; the sixth has a trichogen-tormogen function; and the seventh, eighth, and ninth enveloping cells have a tormogen function. It could not be established whether the dendritic sheath is replaced at molt. In the second and third enveloping cells, there is a differential secretion of cuticular material forming the wall of the distal part of the seta. As a consequence, this wall is not homogeneous. The possible role of this heterogeneity in the formation of the gutter-like apical part of the seta is discussed. A mechanism is proposed by which the pore develops at the transition between the midpart and the apical gutter-like part. Before ecdysis, the distal segments of the sensory cells are still connected with the wall of the old seta in the same way as during intermolt. No degeneration is apparent in the distal segments during preparation for the molt. These morphological findings suggest that sensitivity of the sensilla must be maintained until the moment of the ecdysis.     

Development of a quantitative enzyme-linked immunosorbent assay for vitellin in the mysid Neomysis integer (Crustacea: Mysidacea)

Mysid crustaceans have been put forward by several regulatory bodies as suitable test organisms to screen and test the potential effects of environmental endocrine disruptors. Despite the well-established use of mysid reproductive endpoints such as fecundity, egg development time, and time to first brood release in standard toxicity testing, little information exists on the hormonal regulation of these processes. Control of vitellogenesis is being studied intensively because yolk is an excellent model for studying mechanisms of hormonal control, and vitellogenesis can be chemically disrupted. Yolk protein or vitellin is a major source of nourishment during embryonic development of ovigorous egg-laying invertebrates. The accumulation of vitellin during oocyte development is vital for the production of viable offspring. In this context, we developed a competitive enzyme-linked immunosorbent assay (ELISA) for vitellin of the estuarine mysid Neomysis integer. Mysid vitellin was isolated using gel filtration, and the purified vitellin was used to raise polyclonal antibodies. The ELISA was sensitive within a working range of 4 to 500 ng vitellin/mL. Serial dilutions of whole body homogenates from female N. integer and the vitellin standard showed parallel binding curves, validating the specificity of the ELISA. The intra- and interassay coefficients of variation were 8.2% and 13.8%, respectively. Mysid vitellin concentrations were determined from ovigorous females and eggs at different developmental stages. The availability of a quantitative mysid vitellin ELISA should stimulate further studies on the basic biology of this process in mysids. Furthermore, it could provide a means to better understand and predict chemically induced reproductive effects in mysids.     

Physiological responses of Opuntia ficus-indica to growth temperature

The influences of various day/night air temperatures on net CO₂ uptake and nocturnal acid accumulation were determined for Opuntia ficus-indica, complementing previous studies on the water relations and responses to photosynthetically active radiation (PAR) for this widely cultivated cactus. As for other Crassulacean acid metabolism (CAM) plants, net nocturnal CO₂ uptake had a relatively low optimal temperature, ranging from 11°C for plants grown at day/night air temperatures of 10°C/0°C to 23°C at 45°C/35°C. Stomatal opening, which occurred essentially only at night and was measured by changes in water vapor conductance, progressively decreased as the measurement temperature was raised. The CO₂ residual conductance, which describes chlorenchyma properties, had a temperature optimum a few degrees higher than the optimum for net CO₂ uptake at all growth temperatures. Nocturnal CO₂ uptake and acid accumulation summed over the whole night were maximal for growth temperatures near 25°C/15°C, CO₂ uptake decreasing more rapidly than acid accumulation as the growth temperature was raised. At day/night air temperatures that led to substantial nocturnal acid accumulation (25°C/15°C.). 90% saturation of acid accumulation required a higher total daily PAR than at non-optimal growth temperatures (10°C/0°C and 35°C/25°C). Also, the optimal temperature of net CO₂ uptake shifted downward when the plants were under drought conditions at all three growth temperatures tested, possibly reflecting an increased fractional importance of respiration at the higher temperatures during drought. Thus, water status, ambient PAR, and growth temperatures must all be considered when predicting the temperature response of gas exchange for O. ficus-indica and presumably for other CAM plants.     

Residual effect of germination temperature on the growth of peas

Summary In Pisum sativum there is a marked difference in the final height of the plants depending on the temperature at which the seed is germinated. Significant differences were also found in such parameters as growth rate, node of first flower, seeds per plant, pods per plant as well as flowers per plant.     

Modelling the effect of pH, acidulant and temperature on the growth rate of Yersinia enterocolitica

Growth of two pathogenic and one environmental serotype of Yersinia enterocolitica under acidic conditions and at 4 and 25 degrees C was investigated. At both temperatures the maximum growth inhibitory pH depended on the acidulant used and was in the order acetic greater than lactic greater than citric greater than sulphuric. At the lower temperature the maximum growth inhibitory pH was 0.3-0.5 pH units higher than at 25 degrees C. No difference was observed between the behaviour of pathogenic and environmental serotypes in this respect. Measurement of growth at a number of sub-optimal temperatures and pH values showed that the variation of growth rate with temperature could be represented by a square root plot. The effect of different pH values could be incorporated into the model by replacing the regression coefficient b by its relationship with pH. Values of maximum growth inhibitory pH derived from the model were in good agreement with experimental values with the exception of acetic acid.     

Modelling the effect of temperature, water activity and pH on the growth of Serpula lacrymans

Aims: To predict the risk factors for building infestation by Serpula lacrymans, which is one of the most destructive fungi causing timber decay in buildings. Methods and Results: The growth rate was assessed on malt extract agar media at temperatures between 1·5 and 45°C, at water activity (a_w) over the range of 0·800–0·993 and at pH ranges from 1·5 to 11·0. The radial growth rate (μ) and the lag phase (λ) were estimated from the radial growth kinetics via the plots radius vs time. These parameters were then modelled as a function of the environmental factors tested. Models derived from the cardinal model (CM) were used to fit the experimental data and allowed an estimation of the optimal and limit values for fungal growth. Optimal growth rate occurred at 20°C, at high a_w level (0·993) and at a pH range between 4·0 and 6·0. The strain effect on the temperature parameters was further evaluated using 14 strains of S. lacrymans. The robustness of the temperature model was validated on data sets measured in two different wood‐based media (Quercus robur L. and Picea abies). Conclusions: The two‐step procedure of exponential model with latency followed by the CM with inflection gives reliable predictions for the growth conditions of a filamentous fungus in our study. The procedure was validated for the study of abiotic factors on the growth rate of S. lacrymans. Significance and Impact of the Study: This work describes the usefulness of evaluating the effect of physico‐chemical factors on fungal growth in predictive building mycology. Consequently, the developed mathematical models for predicting fungal growth on a macroscopic scale can be used as a tool for risk assessment of timber decay in buildings.     

Modelling the effect of pH, acidulant and temperature on the growth rate of Yersinia enterocolitica

Growth of two pathogenic and one environmental serotype of Yersinia enterocolitica under acidic conditions and at 4 and 25°C was investigated. At both temperatures the maximum growth inhibitory pH depended on the acidulant used and was in the order acetic > lactic > citric > sulphuric. At the lower temperature the maximum growth inhibitory pH was 0.3-0.5 pH units higher than at 25°C. No difference was observed between the behaviour of pathogenic and environmental serotypes in this respect. Measurement of growth at a number of sub-optimal temperatures and pH values showed that the variation of growth rate with temperature could be represented by a square root plot. The effect of different pH values could be incorporated into the model by replacing the regression coefficient b by its relationship with pH. Values of maximum growth inhibitory pH derived from the model were in good agreement with experimental values with the exception of acetic acid.     

Modification of the effect of high temperature on biochemical processes by perturbed geomagnetic field

The biochemical data on the influence of perturbed geomagnetic field on the hormonal-mediator regulation systems are presented. The possibility of biological effects modification under combined action of perturbed geomagnetic field and high temperature of environment is discussed.