Energy expenditures during spawning by chum salmon Oncorhynchus keta (Walbaum) in British Columbia

Physiological telemetry and proximate tissue analyses were used to assess energy expended by chum salmon Oncorhynchus keta on various behaviours during spawning in Kanaka Creek, British Columbia, Canada, and results were compared with published data on Fraser River sockeye salmon Oncorhynchus nerka , the only other species for which both types of measurements have been taken. Chum salmon arrived at the spawning grounds with body energy densities of 4·84 MJ kg⁻¹ in males and 4·62 MJ kg⁻¹ in females, lower than most sockeye salmon populations, and died with energy densities of c . 4 MJ kg⁻¹, similar to that observed in sockeye salmon and other salmonids. Moisture levels generally increased in body tissues over the spawning life, particularly in female gonads, and lipid levels decreased. Declines in protein observed over the spawning life of other Pacific salmon Oncorhynchus sp. were less evident in Kanaka Creek chum salmon. Holding behaviour constituted the dominant component of the activity schedule and energy budget of both sexes. After holding, the most expensive behaviours were nest digging in females and aggressive displays in males. Dominant males expended the most energy on behaviours each day, as indexed by oxygen consumption (3600 mgO₂ kg⁻¹), while satellite males expended nearly as much (3504 mgO₂ kg⁻¹) but females expended considerably less (2327 mgO₂ kg⁻¹). Kanaka chum salmon engaged more frequently in energetically expensive reproductive behaviours than Stuart River sockeye salmon.     

Fluctuations in the tympanic membrane temperatures of non-restrained captive giant anteaters and southern tamanduas

Members of the family Myrmecophagidae (i.e. anteaters) show a variety of anatomical and behavioural adaptations to deal with their low-energy diet; for example, they all have low body temperatures in comparison with other eutherian mammals. In this study, we investigated the tympanic membrane temperatures ( T _mt) of two giant anteaters and three southern tamanduas, housed in captivity and exposed to natural climatic variations in temperature, using an infrared thermometer. Additionally, we measured external dorsal temperature ( T _d), air temperature ( T _a), substrate temperature ( T _s) and whether the subject was active or not. To understand the effect of time of day on these variables, we recorded them, on the hour, over four 24-h cycles for each animal during which the subjects were non-restrained within their enclosures. The results show that both giant anteaters and southern tamanduas allow their T _mt to reduce between 4.0 and 6.5 °C when they are sleeping. Furthermore, linear regressions between T _mt and T _a or T _s showed that the giant anteaters were much more affected by T _a and T _s than the southern tamanduas. Both species also showed higher T _mt when active (comparing subjects active and inactive at the same T _a). Both species appear to use shallow torpor during a normal 24-h cycle probably as a means to economize energy. The torpor in giant anteaters occurred during the night when asleep, whereas in the southern tamanduas it occurred at any time of day when asleep. The giant anteaters appeared to be more directly affected by environmental temperature than the southern tamanduas.     

Plasma non-esterified fatty acid profiles in wild Atlantic salmon during their freshwater migration and spawning

Total plasma non-esterified fatty acid (NEFA) levels increased significantly in adult Atlantic salmon during the first months of their upstream migration and spawning in the Exploits River, Newfoundland, Canada. The highest levels occurred in May and were 5467±270·43 nmol ml⁻¹ for females and 4617±334·70 nmol ml⁻¹ for males. Significantly higher levels were maintained by females compared with males for most of the upstream migration. Between August and October, total plasma NEFA levels declined by 61% in females but only 23% in males. The decline in plasma monounsaturated and polyunsaturated fatty acid levels accounted for 74% of the loss of NEFAs in females. Specific plasma NEFAs such as 16: 0 (palmitic), 16: 1 (palmitoleic), 18: 1n9 (oleic) and 20: 5n3 (eicosapentaenoic acid) differed significantly between males and females during migration and spawning. The mean gonadosomatic index ( I _G) values of females in May and just prior to spawning were 0·37±0·01 and 10·25±0·32, respectively. The rapid decline in the plasma NEFA content of females coincided with the largest increase in their I _G (1·85±0·02–10·25±0·32). Corresponding I _G values for males were 0·34±0·01 in May and 3·33±0·78 prior to spawning. Plasma NEFA levels of spent salmon did not differ between sexes and were significantly lower than those of salmon preparing to spawn.     

Reproductive biology of the threatened golden galaxias Galaxias auratus Johnston and the influence of lake hydrology

Golden galaxias Galaxias auratus (31–235 mm fork length, L _F) were collected monthly from littoral habitats in Lakes Crescent and Sorell, Tasmania, Australia, between July 2000 and December 2002. Spawning habitats were identified and monitored in both lakes, and surveyed in Lake Crescent. Trends in gonado-somatic indices and reproductive stages of development indicated that gonad development in both sexes begins in midsummer and peaks in late autumn to early winter. Males mature at smaller sizes (50% at 52 mm L _F) than females (50% at 76 mm L _F), larger individuals are predominately females (95% of fish ≥138 mm L _F), and overall male to female ratios are female biased ( c . 1:2). Spawning occurs late autumn to early spring (water temperatures = 1·4–9·7° C) with peaks in spawning activity in winter (mean water temperatures <5° C). Demersal adhesive eggs ( c. 1·5 mm diameter) were found on cobble substrata ( c. 20–250 mm diameter) in littoral areas ( c. 0·2–0·6 m deep) and fecundity of fish 71–181 mm L _F ranged from 619 to 14 478 eggs. The rate of change in water level over the 20 days prior to monthly sampling was important in explaining the occurrence of spent fish and this accounted for temporal differences in spawning between the populations. Lake hydrology influences the reproductive cycle of G. auratus by possibly providing a stimulus for spawning and it controls the availability of spawning habitat in Lake Crescent. Seasonal hydrological cycles ( i.e. rises during late autumn to winter) and a minimum water level of 802·20 m Australian Height Datum in Lake Crescent during autumn (above which littoral areas of cobble substratum are inundated) are critical to G. auratus populations.     

Cyclic feeding and subsequent compensatory growth do not significantly impact standard metabolic rate or critical swimming speed in rainbow trout

Standard metabolic rate ( R _s) and critical swimming speed ( U _crit) were used to assess the aspects of physiological status (stamina) of rainbow trout Oncorhynchus mykiss . Fish were fed either 1·5% body mass daily, 1·5% body mass cyclically (3 weeks of food deprivation followed by 3 weeks of refeeding), a ration based on Stauffer's formula (a maximum temperature-specific ration level) daily or on Stauffer's ration cyclically for 18 weeks. It was hypothesized that if cyclic feeding had no impact on the status of the fish, R _s and U _crit would not cycle with the feeding regime. This hypothesis was supported. No significant difference was found between the mean mass and the fork length of the four groups at the end of the experiment ( P > 0·05). Feeding had no effect on changes in R _s among the four groups, which were significantly different throughout the experiment ( P ≤ 0·05). No significant difference in U _crit was found ( P > 0·05) until at week 12 between groups fed 1·5% body mass ration cyclically and Stauffer's ration daily ( P ≤ 0·05). For groups fed a 1·5% body mass ration cyclically and daily, significant differences occurred at week 15 ( P ≤ 0·05) but no significant difference was found by week 18 ( P > 0·05), suggesting that cyclic feeding does not affect the aspects of physiological status (stamina) of the fish.     

Maturation of walleye by age, size and surplus energy

The probability of annual sexual maturation by male and female walleye Stizostedion vitreum was related to age, size and an index of condition, I _VF=[arcsine(visceral fat)^0·5(body mass)^−0·5]. Most males first matured at ages 2 and 3 years; size explained first maturation, but condition explained later maturation. In contrast, most females first matured at ages 4 and 5 years; maturity of females was more dependent upon condition. Maturity of females at ages 4 and 5 years was significantly correlated with average I _VF of the population ( PI _VF). The size reached by age 2 years (early growth) was correlated with the PI _VF. Growing degree-days, Secchi depth, latitude and lake morphology were not correlated with the PI _VF. Annual variations in female spawning stock size were related to the condition of the females, presumably reflecting the net acquisition of energy in the preceding growing season. Annual variations within lakes in the net acquisition of energy may exceed the variations in energy availability between lakes, dictated by lake morphology and geography. Thus, assessment of condition could be used to predict annual potential spawning stock size and egg production.     

The effects of temperature and hyperoxia on arterial PO2 and acid-base status in Piaractus mesopotamicus

The effects of hyperoxia and change of temperature (range 20–30° C) on blood gases were studied in the teleost fish Piaractus mesopotamicus , native to several major river systems in Brazil. Large hyperoxia-induced increases of arterial P o₂ ( P _ao₂) indicated that true branchial blood shunts are negligible in relation to total gill perfusion. This implies that blood gases will be influenced by ventilation rather than by shunts. Acute variations of temperature ( t ) were accompanied by changes of arterial blood pH (on the average Δ p H_aΔt⁻¹ of — 0·015 units °C⁻¹), due mainly to alterations of P _aco₂: 2·4 mmHg at 20° C, 5·0 mmHg at 30° C. Concomitantly, P _ao₂ declined from 116 mmHg (20° C) to 89 mmHg (30° C). The data suggest that temperature-induced changes of acid-base status depend mainly on gill ventilation and that the decrease of P _ao₂ with higher temperature is a result of this regulation.     

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.     

DOUBLE PULSE LABELLING WITH 3H-THYMIDINE: A METHOD FOR CALCULATING CELL POPULATIO KINETICS

A method was developed for calculating cell population kinetics with the aid of double pulse labelling with ³H-TdR. The labelling index was measured from auto-radiographs of the oral epithelium of two groups of 30-day-old rats. One group was injected once with ³H-TdR the other twice, with a time interval of 90 min between injections. DNA synthesis time was calculated from the equation:
   
where T _s= synthesis time; LI₁= labelling index in the single-injected group; LI₂= labelling index in the double-injected group; and T _i= time interval between injections. Synthesis time in the palate was 4.8 hr and 7.6 hr in the tongue. Generation time was calculated from the equation: T _g= ( T _s/LI₁) × 100, where T _g= generation time. Generation time in the palate was 46.1 hr and 75.8 hr in the tongue     

The reproductive ecology of the southern red tabira bitterling Acheilognathus tabira jordani in Japan

The life history, population and reproductive variables of the southern red tabira bitterling Acheilognathus tabira jordani were investigated in a lowland reach of the River Ohara in Shimane Prefecture, western Honshu, Japan. Acheilognathus t. jordani , like all other species of bitterling, lays its eggs on the gills of freshwater mussels. It was the only species of bitterling present in the study reach, and three species of bivalve mussel were available to it for spawning: Anemina arcaeformis, Anodonta lauta and Corbicula leana . Spawning by A.t. jordani was recorded between early April and early July in 2003 and began at a size of 38· 0 mm standard length ( L _S) in the 1+ age class. Ovipositor length ( L _OP) during oviposition was positively correlated with female L _S, and showed significant seasonal variation, with a mean ± s.d. L _OP of 27· 5 ± 5· 3 mm ranging from 16· 8 to 42· 0 mm during the spawning period, which was shorter than that of a previously studied A. t. tabira population. Eggs of this subspecies are relatively long and elliptic in shape, with a volume of c. 2· 4 mm³. Egg number correlated positively with female L _S and both egg shape and volume changed significantly with season. The population size of adults was estimated to be 850 individuals, and comprised age 0+ to 3+ individuals with L _S ranging from 12· 0 to 72· 2 mm. The population sex ratio was significantly female biased, with seven females: three males. Egg shape and size and L _OP during oviposition in the present A. tabira population may be the result of local adaptations to the mussel species utilized and no competition with other bitterling species for spawning sites.     

Reproduction in the dusky grouper from the southern Mediterranean

Demographic data and gonad histology confirmed that the dusky grouper Epinephelus marginatus is a protogynous hermaphrodite that follows a monandric pathway to sexual development. Females reached first sexual maturity at 36·7 cm L_s and estimated mean length at first maturity (L₅₀) was 43·8 cm L_s for females and 81·3 cm L_s for males. Adult sex ratios during the reproductive period were c. 3·5: 1 females to males. Females exhibited group-synchronous ovarian development and multiple ovulation occurred over the spawning period. Gonads were ripe from early May and spawning occurred from June until early September. The size of ripe testes (0·6% W )indicated strong oligospermy and suggested a mating system with no sperm competition. Sexual transition was protogynous involving regression of ovarian tissue and proliferation of testicular tissue in the gonads. Transitional individuals occurred from May through November and accounted for 9% of sampled adult population. Sex change occurred in fish 69–93 cm (L_s) long and the size distributions of males and females overlapped over 27% of the L_s range. Special zones were recognized as gathering areas for sexually mature dusky groupers during the reproductive period.     

A study of stomatal mechanics using the cell pressure probe

The relationship between stomatal aperture ( a ) and guard cell pressure ( P _g) was measured directly in four different species ( Vicia faba, Tradescantia virginiana, Ginkgo biloba and Nephrolepis exaltata ) using a special cell pressure probe technique. The effect of epidermal turgor ( P _ep) on this relationship was also measured in T. virginiana . The relationship was sigmoidal for V. faba and T. virginiana , but entirely convex for G. biloba and N. exaltata. Epidermal turgor was found to have a pronounced closing effect on stomata of T. virginiana . Maximum aperture with full epidermal turgor (0·92 MPa) was about half that with zero epidermal turgor. Also, with full epidermal turgor stomata of T. virginiana did not begin to open until P _g was more than 1·25 MPa. These characteristics were used to develop an expression for a as a function of P _g and P _ep. Results for the different species are compared and discussed in terms of possible advantages and limitations of water economy.     

Heterogeneous Na+ Sensitivity of Na+,K+-ATPase Isoenzymes in Whole Brain Membranes

Abstract: The Na⁺ sensitivity of whole brain membrane Na⁺,K⁺-ATPase isoenzymes was studied using the differential inhibitory effect of ouabain (α1, low affinity for ouabain; α2, high affinity; and α3, very high affinity). At 100 m M Na⁺, we found that the proportion of isoforms with low, high, and very high ouabain affinity was 21, 38, and 41%, respectively. Using two ouabain concentrations (10⁻⁵ and 10⁻⁷ M ), we were able to discriminate Na⁺ sensitivity of Na⁺, K⁺-ATPase isoenzymes using nonlinear regression. The ouabain low-affinity isoform, α1, exhibited high Na⁺ sensitivity [ K _a of 3.88 ± 0.25 m M Na⁺ and a Hill coefficient ( n ) of 1.98 ± 0.13]; the ouabain high-affinity isoform, α2, had two Na⁺ sensitivities, a high ( K _a of 4.98 ± 0.2 m M Na⁺ and n of 1.34 ± 0.10) and a low ( K _a of 28 ± 0.5 m M Na⁺ and an n of 1.92 ± 0.18) Na⁺ sensitivity activated above a thresh old (22 ± 0.3 m M Na⁺); and the ouabain very-high-affinity isoform, α3, was resolved by two processes and appears to have two Na⁺ sensitivities (apparent K _a values of 3.5 and 20 m M Na⁺). We show that Na⁺ dependence in the absence of ouabain is the result of at least of five Na⁺ reactivities. This molecular functional characteristic of isoenzymes in membranes could explain the diversity of physiological roles attributed to isoenzymes.     

Reduced swimming performance in delta smelt infected with Mycobacterium spp.

Delta smelt Hypomesus transpacificus infected with Mycobacterium spp. swam significantly more slowly (mean ± s.e ., 24±5 ± 1·2 cm s ⁻¹) than uninfected fish (30·0 ± 1·7 cm s ⁻¹). Differences in swimming performance were not attributable to differences in fish size ( L _s or wet mass), condition factor or laboratory holding duration. Similar proportions of non-fatigue-related swimming failure among the uninfected and infected fish indicated that mycobacteriosis did not affect the willingness of delta smelt to swim in the flume. Level of infection, measured for the dominant M. chelonae pathogen using enzyme-linked immunosorbent assay (ELISA), did not affect critical swimming velocity.     

Effects of temperature, body size and feeding on rates of metabolism in young‐of‐the‐year haddock

The mean rate of oxygen consumption (routine respiration rate, R _R, mg O₂ fish⁻¹ h⁻¹), measured for individual or small groups of haddock Melanogrammus aeglefinus (3–12 cm standard length, L _S) maintained for 5 days within flow‐through respiratory chambers at four different temperatures, increased with increasing dry mass ( M _D). The relationship between R _R and M _D was allometric ( R _R = α  M ^b ) with b values of 0·631, 0·606, 0·655 and 0·650 at 5·0, 8·0, 12·0 and 15·0° C, respectively. The effect of temperature ( T ) and M _D on mean R _R was described by     indicating a Q ₁₀ of 2·27 between 5 and 15° C. Juvenile haddock routine metabolic scope, calculated as the ratio of the mean of highest and lowest deciles of R _R measured in each chamber, significantly decreased with temperature such that the routine scope at 15° C was half that at 5° C. The cost of feeding ( R _SDA) was c . 3% of consumed food energy, a value half that found for larger gadoid juveniles and adults.     

Surface free energies of oral streptococci and their adhesion to solids

Abstract The adhesion of 3 strains of oral streptococci from a buffered suspension onto 3 different solid substrata was studied. Representative strains of streptococci were selected on the basis of their surface free energy ( γ _b), namely Streptococcus mitis L1 ( γ _b= 37 mJ·m⁻²), Streptococcus sanguis CH3 (95 mJ·m⁻²) and Streptococcus mutans NS (117 mJ·m⁻²). Solid substrata were also selected on basis of their surface free energy ( γ _s), and included polytetrafluorethylene ( γ _s= 20 mJ·m⁻²), polymethylmethacrylate (53 mJ·m⁻²) and glass (109 mJ·m⁻²). Bacterial adhesion was measured as the number of bacteria adhering per cm² at equilibrium. Equilibrium was usually obtained within 20 min. S. sanguis CH3, having an intermediate surface free energy did not show a clear preference for any of the 3 solids. S. mitis L1, however, the lowest surface free energy strain, adhered in highest numbers to the low energy solid PTFE, whereas the highest γ _b strain, S. mutans NS, adhered in highest numbers to the highest γ _s solid, glass. Calculation of the interfacial free energy of adhesion ( ΔF _adh) for each bacterial strain showed that this parameter was predictive of bacterial adhesion to solid substrata.     

Is the large plasmid of 120 MDa in Shigella sonnei composed of two DNA segments—90 and 30 MDa?

Abstract The reversibility of adhesion of 3 representative strains of oral streptococci from a phosphate-buffered suspension onto 5 different solid substrata was studied.
Streptococcus mitis T9 (surface free energy γ_b= 39 mJ · m⁻²). Streptococcus sanguis CH3 (γ_b= 95 mJ · m⁻²) and Streptococcus mutans NS (γ_b= 117 mJ · m⁻²) were selected on basis of their surface free energy. Solid substrata were employed with a surface free energy γ_s ranging from 20 mJ · m⁻² for polytetrafluorethylene to 109 mJ · m⁻² for glass. Bacterial suspensions containing 2.5 × 10⁹ cells per ml were incubated with 2 samples of each substratum. After 1 h the number of adhering bacteria was evaluated on one sample, while the second sample was kept for another hour at a 10-fold lower bacterial concentration. Bacteria with a low surface free energy desorbed only from substrata with a high surface free energy, while bacteria with a high surface free energy desorbed from substrata with a low surface free energy. Thus low energy bacterial strains adhered reversibly to high energy substrata and vice versa. Similar observations were made with polystyrene particles. Calculation of the interfacial free energy of adhesion (Δ F _adh) for each bacterial strain as well as for the polystyrene particles showed that a reversible adhesion was associated with a positive Δ F _adh, denoting unfavourable adhesion conditions upon a thermodynamic basis.     

On the life history of the lesser gurnard (Scorpaeniformes: Triglidae) inhabiting the Agulhas Bank, South Africa

Growth analysis based on sectioned sagittal otoliths revealed the lesser gurnard Chelidonichthys queketti on the Agulhas Bank to be relatively fast growing and long lived, with ages of up to 7 years being recorded. Total length at age (mm) was described best by the specialized von Bertalanffy growth model as L _T=306·1 (1 − e^{0·53(t+0·18)}). First approximations of total, natural and fishing mortality rates were determined at 0·73, 0·38 and 0·35 year⁻¹ respectively. The adult population was male dominated with a sex ratio of 1 female: 1·2 males with the mean size of males and females being similar. The lesser gurnard is an iteroparous species with females maturing by the end of the first year of life (195 mm L _T), thereafter spawning throughout the year with reproductive activity peaking over spring and late summer. The lesser gurnard appears to exhibit similar life-history patterns to other triglid species in that it can be classified as a generalist. Generalistic life-history characteristics such as a fast growth rate, early sexual maturity at a relatively large size, a non-seasonal spawning pattern, feeding on a variety of prey organisms and the ability to inhabit various substrata could all contribute to it maintaining a high biomass on the Agulhas Bank.     

CELL PROLIFERATION IN THE CASTRATE MOUSE SEMINAL VESICLE IN RESPONSE TO TESTOSTERONE PROPIONATE

The cell proliferation kinetics following induced DNA synthesis in the mouse seminal vesicle were measured after treatment with testosterone propionate. Fraction labelled mitosis curves at 24, 48 and 72 hr after injection gave t ₂ values of 1·5, 2·0 and 1·8 hr respectively, and t _s values of 10·5, 8·0 and 8·0 hr. T _c measured 48 hr after stimulation was 17·5 hr. Growth fraction rose from 0·14 at 24 hr to 0·64 at 48 hr, and fell to 0·32 by 72 hr. A simple model is proposed in which the rise and fall of mitotic index and labelled index is determined by the 'cell distribution ratio'.     

Growth and physiological changes during metamorphosis of Senegal sole reared in the laboratory

The metamorphosis of Solea senegalensis was studied in larvae reared at 20° C and fed four different feeding regimes. A, Artemia (4 nauplii ml⁻¹); B, Artemia (2 nauplii ml⁻¹); C, mixed diet (2 nauplii ml⁻¹ and 3 mg ml⁻¹ microencapsulated diet); and D, microencapsulated diet (3·7 mg ml⁻¹). Rotifers were also supplied in all cases during the first days of feeding. These feeding regimes supported different growth rates during the pre-metamorphosis period (regime A, G=0·376 day⁻¹; regime B, G=0·253 day⁻¹; regime C, G=0·254 day⁻¹; regime D, G=0·162 day⁻¹). Larvae started metamorphosis 9 days after hatching (DAH) when fed the regime A, 13 DAH with regime B, 11 DAH with regime C and 15 DAH with regime D. A minimum 5·6–5·9 mm L_T was required under all feeding regimes to initiate the metamorphosis. Eye translocation was completed when the larvae reached 8·6–8·7 mm L_T (regimes A, B and C), but only 7·3 mm L_T with regime D. 4·4–6·2 days were required to complete eye migration under the regimes A, B and C, and 18·3 days under the regime D. This transformation is concomitant with changes in body reserves, and with the pattern of some digestive enzymes.