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IntroductionChanges in temperature can fundamentally transform how species interact, causing wholesale shifts in ecosystem dynamics and stability. Yet we still have a limited understanding of how temperature-dependence in physiology drives temperature-dependence in species-interactions. For predator-prey interactions, theory predicts that increases in temperature drive increases in metabolism and that animals respond to this increased energy expenditure by ramping up their food consumption to meet their metabolic demand. However, if consumption does not increase as rapidly with temperature as metabolism, increases in temperature can ultimately cause a reduction in consumer fitness and biomass via starvation.MethodsHere we test the hypothesis that increases in temperature cause more rapid increases in metabolism than increases in consumption using the California spiny lobster (Panulirus interruptus) as a model system. We acclimated individual lobsters to temperatures they experience sacross their biogeographic range (11, 16, 21, or 26°C), then measured whether lobster consumption rates are able to meet the increased metabolic demands of rising temperatures.Results and discussionWe show positive effects of temperature on metabolism and predation, but in contrast to our hypothesis, rising temperature caused lobster consumption rates to increase at a faster rate than increases in metabolic demand, suggesting that for the mid-range of temperatures, lobsters are capable of ramping up consumption rates to increase their caloric demand. However, at the extreme ends of the simulated temperatures, lobster biology broke down. At the coldest temperature, lobsters had almost no metabolic activity and at the highest temperature, 33% of lobsters died. Our results suggest that temperature plays a key role in driving the geographic range of spiny lobsters and that spatial and temporal shifts in temperature can play a critical role in driving the strength of species interactions for a key predator in temperate reef ecosystems.

The conservation benefits of marine reserves are well established but their contribution to adjacent fisheries via spillover is less certain and context‐dependent. Theoretical predictions do not always match empirical evidence from individual reserves, so carefully designed studies are essential for accurately assessing spillover and its contribution to fisheries. Biomass buildup within reserves, and spillover from reserve borders, also usually takes time to develop. In 2003, a network of no‐take marine reserves was established in the Northern Channel Islands (NCI) of southern California (CA) to conserve biodiversity and to eventually enhance local fisheries through spillover of larvae, juveniles, and adults. The reserve network impacted the local CA spiny lobster (Panulirus interruptus) fishery by removing about 20% of fishing grounds in the NCI. In 2008, a collaborative fisheries research effort detected substantial lobster population increases within reserves, and an indication of the possible spillover of adult lobsters across reserve borders. To estimate whether and how much populations within reserves, and spillover from reserves, have increased through time, we repeated the sampling program 10 years later in 2018 at two of the three original reserves. Scientific trapping was conducted prior to the fishing season along a spatial gradient beginning deep within the reserves to reference sites located outside (≥2 km) of reserve borders. Results showed that legal‐sized lobster abundance in traps (catch per unit effort) increased by 125%–465% deep inside reserves, and by 223%–331% at sites near to reserve borders, and by nearly 400% just outside of reserve borders over the 10‐year period, thus indicating a substantial increase in spillover across reserve borders. A similar pattern was observed in lobster biomass caught in traps at the two reserves. This study demonstrates how spillover scales with biomass buildup and that collaborative fisheries research can be used to assess the efficacy of marine reserves as fishery management tools worldwide. [ABSTRACT FROM AUTHOR]

A major goal of ecosystem-based fisheries management is to prevent fishery-induced shifts in community states. This requires an understanding of ecological resilience: the ability of an ecosystem to return to the same state following a perturbation, which can strongly depend on species interactions across trophic levels. We use a structured model of a temperate rocky reef to explore how multi-trophic level fisheries impact ecological resilience. Increasing fishing mortality of prey (urchins) has a minor effect on equilibrium biomass of kelp, urchins, and spiny lobster predators, but increases resilience by reducing the range of predator harvest rates at which alternative stable states are possible. Size-structured predation on urchins acts as the feedback maintaining each state. Our results demonstrate that the resilience of ecosystems strongly depends on the interactive effects of predator and prey harvest in multi-trophic level fisheries, which are common in marine ecosystems but are unaccounted for by traditional management.

Abstract The conservation benefits of marine reserves are well established but their contribution to adjacent fisheries via spillover is less certain and context‐dependent. Theoretical predictions do not always match empirical evidence from individual reserves, so carefully designed studies are essential for accurately assessing spillover and its contribution to fisheries. Biomass buildup within reserves, and spillover from reserve borders, also usually takes time to develop. In 2003, a network of no‐take marine reserves was established in the Northern Channel Islands (NCI) of southern California (CA) to conserve biodiversity and to eventually enhance local fisheries through spillover of larvae, juveniles, and adults. The reserve network impacted the local CA spiny lobster (Panulirus interruptus) fishery by removing about 20% of fishing grounds in the NCI. In 2008, a collaborative fisheries research effort detected substantial lobster population increases within reserves, and an indication of the possible spillover of adult lobsters across reserve borders. To estimate whether and how much populations within reserves, and spillover from reserves, have increased through time, we repeated the sampling program 10 years later in 2018 at two of the three original reserves. Scientific trapping was conducted prior to the fishing season along a spatial gradient beginning deep within the reserves to reference sites located outside (≥2 km) of reserve borders. Results showed that legal‐sized lobster abundance in traps (catch per unit effort) increased by 125%–465% deep inside reserves, and by 223%–331% at sites near to reserve borders, and by nearly 400% just outside of reserve borders over the 10‐year period, thus indicating a substantial increase in spillover across reserve borders. A similar pattern was observed in lobster biomass caught in traps at the two reserves. This study demonstrates how spillover scales with biomass buildup and that collaborative fisheries research can be used to assess the efficacy of marine reserves as fishery management tools worldwide.

The United States is home to some of the most sustainably-managed fisheries in the world, but a surprisingly small number of Americans eat seafood that originated in U.S. waters. An average of 90% of the seafood consumed by Americans is imported. At the same time, the U.S. has become the sixth largest supplier of seafood in the world. The goal of this project is to reveal the supply chains of domestic species in order to better understand why more of our domestic seafood isn’t kept at home. Using an ocean-to-table model, we traced three species of iconic American-caught seafood that have particularly interesting supply chains: American lobster (Homarus americanus), California market squid (Doryteuthis opalescens), and California spiny lobster (Panulirus interruptus). By compiling available landing and export data for these fisheries, and by interviewing individuals involved in each step of the supply chain, we increased the transparency of these three seafood supply chains and help reconnect consumers with their seafood. We found that most of the locally-caught CA market squid is exported abroad, but a small portion comes back to the U.S. for local consumption after being processed in China. Both lobster species are exported overseas. Exports to China continue to increase because they are highly coveted by an increasing middle class.

Marine Protected Areas (MPAs) are designed to enhance biodiversity and ecosystem services. Some MPAs are also established to benefit fisheries through increased egg and larval production, or the spillover of mobile juveniles and adults. Whether spillover influences fishery landings depend on the population status and movement patterns of target species both inside and outside of MPAs, as well as the status of the fishery and behavior of the fleet. We tested whether an increase in the lobster population inside two newly established MPAs influenced local catch, fishing effort, and catch-per-unit-effort (CPUE) within the sustainable California spiny lobster fishery. We found greater build-up of lobsters within MPAs relative to unprotected areas, and greater increases in fishing effort and total lobster catch, but not CPUE, in fishing zones containing MPAs vs. those without MPAs. Our results show that a 35% reduction in fishing area resulting from MPA designation was compensated for by a 225% increase in total catch after 6-years, thus indicating at a local scale that the trade-off of fishing ground for no-fishing zones benefitted the fishery. [ABSTRACT FROM AUTHOR]

This dissertation describes collaborative fisheries research (CFR) on Californiaspiny lobster (Panulirus interruptus) at the Santa Barbara Channel Islands (SBCI).The research goals addressed in this work include: (1) establishing a collaborativeapproach to gathering fisheries data for assessments and management; (2)assessment of marine reserves at SBCI; (3) estimating mortality rates of lobsterspopulations throughout the SBCI marine reserve network; and (4) construction offisheries models that provide context for interpreting mortality rates I estimated.CFR enhanced assessment of marine reserves established in 2003 at the SBCIin terms of their impact in P. interruptus population structure and fisheryinteractions. After six years of reserve protection, there was a four to eight-foldincrease in trap yield, a 5–10% increase in the mean size (carapace length) of legal sized lobsters, and larger size structure of lobsters trapped inside versus outside of three replicate reserves. Patterns in trap data were corroborated by visual SCUBA surveys that indicated a four to six-fold increases in lobster density inside reserves. These results indicate that marine reserves have strong conservation benefits for P. interruptus. Inside reserves, trap performance (the number and mean size of legal-sized lobsters caught in traps) was significantly influenced by proximity to reserve borders, a pattern that suggests net emigration of lobster from inside reserves to adjacent fished areas (spillover). Interestingly, spillover was not apparent in trap yields or commercial fishery effort distribution outside reserves, nor was it apparent in tagging studies. This suggests that spillover from reserves may have little influence of fishery yield outside reserves. However, yield due to spillover might increase as the reserves age and lobster biomass continues to increase inside reserves.Mean total mortality (Z) of female lobsters was lower at sites inside reserves (Z= 0.21 [±0.07 SE]) than at sites outside reserves (Z = 0.59 [±0.02 SE]). Meanmortality at all sites inside reserves, and among sites near reserve centers (where Z= 0.17 [±0.05 SE]), was similar to estimates of natural mortality for other temperate spiny lobster species. Among sites inside reserves, there was a positive relationship between mortality and proximity to reserve borders, but this relationship was absent among sites outside reserves. Mortality estimates were much more variable among sites inside reserves than at sites in fished areas. Results of YPR models suggest that increased effort in this fishery will not resultin commensurate increases in yield. However, current spawning potential at SBCI is ~20% (of virgin conditions), and this could decrease with increased effort. Ourcollaborative framework provides a stable and inclusive framework for conductingfuture research that informs management of this fishery and fosters stakeholdersupport.

Marine protected areas (MPAs) are widely used to rebuild depleted populations for exploited species, but their effectiveness hinges on adequate knowledge of the factors dictating population dynamics for target organisms. Estimates of connectivity via larval dispersal often are included in MPA design, but movement patterns, habitat associations, and habitat-specific survival rates of juveniles and adults, which often are unknown, also will influence MPA effectiveness. California spiny lobsters (Panulirus interruptus Randall) are the target of intense commercial and recreational fishing in southern California, but we lack basic information about home range and habitat use of lobsters to determine if MPAs planned for the region will enhance abundance. Working within and outside of the La Jolla Ecological Reserve (LJER) in southern California, we (i) quantified lobster movement patterns and home ranges over short (nightly – weekly) and long (1 – 14 months) time scales using acoustic telemetry, (ii) surveyed lobsters to determine day and night habitat associations, and (iii) tethered lobsters to assess habitat-specific predation risk. Lobsters exhibited high site fidelity, proclivities for homing, and small home ranges (geometric mean of 651 m2 and 5,912 m2 per week based on 50% and 95% Kernel Utilization Distributions (KUDs), respectively) that encompassed only a fraction of a small MPA, even over periods of several months. Lobsters were strongly associated with rocky habitat during the day (when in shelters) but were associated with the red algae Plocamium cartilagineum at night (when feeding). Lobster relative survival rates were high across vegetated and unvegetated habitats at night, but lobsters were protected from predators by surfgrass (Phyllopsadix torreyi) habitat during the day. Our results highlight the need to consider how movement patterns vary over short and long time scales, and how patterns of habitat use may vary from day to night for nocturnally active species such as spiny lobsters when planning MPAs.

Microsatellite sequences were isolated from both non-enriched and enriched genomic libraries of California spiny lobster, Panulirus interruptus. Eight consistently amplifying, scorable and polymorphic loci were characterized for 79 individuals collected at Santa Cruz and San Clemente Islands, California, and tested for cross-species amplification in four closely related Panulirus spp., as well as four other species of the order Achelata. The number of alleles observed per locus ranged from three to 54 and observed heterozygosities ranged from 0.57 to 0.98. Quality control testing shows that all loci were reliably scorable, independently segregating, inherited in Mendelian ratios, and had low to moderate (≤14.4%) frequencies of null alleles and high statistical power for detecting fine scale genetic structure.

The extent to which exploitation may alter marine life population structure anddynamics is incompletely understood because past research overwhelmingly relies on time series that date back less than 30 years and begin long after the onset ofexploitation. This study seeks to partially fill this gap with respect to the Californiaspiny lobster, Panulirus interruptus, by fitting a recently developed Bayesian sizestructuredmodel to a newly assembled 120-year historical time series of catch and effort to quantify the effects of fishing on the population’s size-structure and dynamics. In a little over a century, as fishing effort increased, the abundance andproportion of large-sized lobster (> 100mm carapace length) progressively declined.Severely reducing the lobster's average lifespan and size has increased thepopulation's short-term variability, potentially diminishing the resilience of thespecies and the kelp forest ecosystem by compounding the effects of ‘fishing downthe food web.’  This work also demonstrates how integrating nontraditional independent historical sources into ecological studies can help meet challenges typically posed by longer time series, including validating potentially questionable historical data points, corroborating model predictions, verifying the temporal scale of baselines, and identifying alternative anthropogenic causes for the observed or predicted ecological variability. In the lobster case study, historical sources verified an annual catch estimate previously considered an outlier, strongly corroborated the model predictions of fishery-induced lobster population size truncation, and clarified that 1888 was a reasonable pre-exploitation baseline. Further, placing the model reconstruction within the broader historical context of marine conservation over the last 300 years illuminates how lobster conservation tactics based on outdated ecological ideas have facilitated and accelerated the size truncation of the lobster population, and may be undercutting contemporary ecosystem-based conservation measures such as reserves. This approach, which melds contemporary ecological and historical techniques, could be applied to any species to achieve a deeper and more comprehensive understanding of the history of the environment.

While the California spiny lobster ( Panulirus interruptus ) is an important commercial and recreational fishery species in California, there is a lack of data on bioaccumulation for the species. This study examined pollutant tissue concentrations in lobsters from San Diego Bay, California. Observed lobster pollutant tissue concentrations in tail muscle were compared to State of California pollutant advisory levels. Concentrations were then used to conduct risk assessment using catch data from the California Department of Fish and Wildlife. Study results found little bioaccumulation of organic pollutants in tail tissue, likely due to low observed lipids. Mercury was present, predominantly in methyl form, at concentrations above advisory levels. Recreational catch data for San Diego Bay showed increased non-cancer risk for fishers at the 90th percentile or greater of reported annual catch. Further studies should focus on non-tail tissues, as exploratory whole lobster samples ( n  = 2) showed elevated organic pollutants and metals. [ABSTRACT FROM AUTHOR]

El trabajo de campo sobre la costa oeste de la península de Baja California entre los años 2000 y 2005 dio como resultado la ampliación del ámbito geográfico norteño, desde la Bahía de Santa María hasta Punta Eugenia y sus zonas aledañas, para una población permanente de la langosta pinta Panulirus inflatus (Bouvier, 1895). Registros de esta especie para Bahía de Los Ángeles (golfo de California) e isla Guadalupe, México y San Diego, California, en Estados Unidos de América están considerados extralímite y se relacionan con el incremento en la temperatura promedio en el golfo, la condición de calentamiento del agua marina en el Pacifico oriental o el evento El Niño. Adicionalmente, un análisis histórico detallado sobre la distribución de la langosta roja P. interruptus (Randall, 1893) sugiere que los registros al sur de Bahía Magdalena, Baja California Sur y aquellos de la parte sur del Golfo de California son extralímite. Sin embargo, los individuos de Bahía de Los Ángeles y sus áreas aledañas (incluyendo Isla Tiburón y Guaymas, Sonora) parecen representar una población que quedó aislada de aquella de la costa oeste de la península de Baja California después de que el corredor marino medio-peninsular, presente en el período Terciario neógeno, se cerró al emerger completamente la península.Fieldwork along the west coast of the Baja California peninsula has resulted in a northern range extension, from Bahía Santa María to Punta Eugenia and vicinity, Baja California Sur, Mexico, for a permanent population of the pinto lobster Panulirus inflatus (Bouvier, 1895). Records of this species from Ángel de la Guarda Island (within the Gulf of California) and Guadalupe Island, Mexico and San Diego, California, USA are considered extralimital and related to annual water warming in the Gulf and the Eastern Pacific warm water condition or El Niño event, respectively. In addition, an historic analysis of the red lobster distribution, P. interruptus (Randall, 1893), suggests that records south of Magdalena Bay and those from the southern Gulf of California are extralimital. Nevertheless, the individuals of Bahía de Los Ángeles and vicinity (including Tiburón Island and Guaymas, Sonora) seems to represent a population that became isolated from that of the west coast of the Baja California Peninsula after the mid-peninsular sea-way corridor, present in the Tertiary Neogene period, was closed once the peninsula completely emerged.

The procedure for phase extension (PX) involves gradually extending the initial phases from low resolution (e.g. ∼8 Å) to the high-resolution limit of a diffraction data set. Structural redundancy present in the viral capsids that display icosahedral symmetry results in a high degree of non-crystallographic symmetry (NCS), which in turn translates into higher phasing power and is critical for improving and extending phases to higher resolution. Greater completeness of the diffraction data and determination of a molecular replacement solution, which entails accurately identifying the virus particle orientation(s) and position(s), are important for the smooth progression of the PX procedure. In addition, proper definition of a molecular mask (envelope) around the NCS-asymmetric unit has been found to be important for the success of density modification procedures, such as density averaging and solvent flattening. Regardless of the degree of NCS, the PX method appears to work well in all space groups, provided an accurate molecular mask is used along with reasonable initial phases. However, in the cases with space group P1, in addition to requiring a molecular mask, starting the PX at a higher resolution (e.g. 6 Å) overcame the previously reported problems due to Babinet phases and phase flipping errors. [ABSTRACT FROM PUBLISHER]

In this study, the effects of adding steroid hormones to the feeds administered to cultures of the spiny lobster, Panulirus interruptus (J. W. Randall, 1840), were investigated. The results indicate that the addition of steroid hormones in the feeds evoke (1) an increase in the ratio of ovigerous versus non-ovigerous females of up to 13.68% as compared to the controls; (2) fertilized females were present several months longer in the treatment group than in the control group; and (3) the ovigerous period, i.e., the time from fertilization until release of the young, was substantially shorter under a regime of feeding with steroid hormone additions. As a conclusion, enrichment of the feeds with steroid hormones thus distinctly increases the yield of young spiny lobsters in the course of a year cycle. [ABSTRACT FROM AUTHOR]

The article presents a study about the nutritional condition of juveniles and subadults of the California spiny lobster or Panulirus interruptus in Baja California Peninsula. It examines the impact of subtropical environmental conditions to the health condition of the lobsters. It cites the importance of several nutrition to the lobster's health including proteins, lipids, and carbohydrates.

A chymotrypsin was purified from the gastric juice of California spiny lobster ( Panulirus interrutpus), using preparative electrophoresis and affinity chromatography on agarose- p-aminobenzamidine. The molecular mass was estimated by polyacrylamide gel electrophoresis (SDS-PAGE) under denaturing conditions to be 28 kDa. Chymotrypsin activity was totally inhibited by phenylmethylsulfonyl fluoride (PMSF) and chymostatin. Lobster chymotrypsin had optimal pH 7.0-8.0 and temperature of 55 °C. The enzyme is highly stable under a wide range of pH (retaining up to 80 % of activity after 1 h of incubation at pH 3.0, 5.0, and 12.0), showing higher stability at pH 8.0, and was inactivated after 20 min at 55 °C. Lobster chymotrypsin was able to hydrolyze protein substrates at as low as pH 3.0. These results are consistent with the findings of enzyme stability. Activity was assessed after incubation of enzyme with different organic solvents (in the range of 10-50 %); when tested in the presence of acetone, ethanol, propanol, and butanol, lobster chymotrypsin residual activity was >80 %; whereas in the presence of dimethyl sulfoxide (DMSO) and toluene, lobster chymotrypsin residual activity was <80 %. Deduced amino acid sequence, corroborated by mass spectrometry, was determined. [ABSTRACT FROM AUTHOR]

Background Dopamine (DA) can produce divergent effects at different time scales. DA has opposing immediate and long-term effects on the transient potassium current (IA) within neurons of the pyloric network, in the Panulirus interruptus stomatogastric ganglion. The lateral pyloric neuron (LP) expresses type 1 DA receptors (D1Rs). A 10 min application of 5-100 μM DA decreases LP IA by producing a decrease in IA maximal conductance (Gmax) and a depolarizing shift in IA voltage dependence through a cAMP-Protein kinase A (PKA) dependent mechanism. Alternatively, a 1 hr application of DA (⩾5nM) generates a persistent (measured 4 hr after DA washout) increase in IA Gmax in the same neuron, through a mechanistic target of rapamycin (mTOR) dependent translational mechanism. We examined the dose, time and protein dependencies of the persistent DA effect. Results We found that disrupting normal modulatory tone decreased LP IA. Addition of 500pM-5nM DA to the saline for 1 hr prevented this decrease, and in the case of a 5nM DA application, the effect was sustained for >4 hrs after DA removal. To determine if increased cAMP mediated the persistent effect of 5nM DA, we applied the cAMP analog, 8-bromo-cAMP alone or with rapamycin for 1 hr, followed by wash and TEVC. 8-bromo-cAMP induced an increase in IA Gmax, which was blocked by rapamycin. Next we tested the roles of PKA and guanine exchange factor protein activated by cAMP (ePACs) in the DA-induced persistent change in IA using the PKA specific antagonist Rp-cAMP and the ePAC specific agonist 8- pCPT-2'-O-Me-cAMP. The PKA antagonist blocked the DA induced increases in LP IA Gmax, whereas the ePAC agonist did not induce an increase in LP IA Gmax. Finally we tested whether extracellular signal regulated kinase (Erk) activity was necessary for the persistent effect by co-application of Erk antagonists PD98059 or U0126 with DA. Erk antagonism blocked the DA induced persistent increase in LP IA. Conclusions These data suggest that dopaminergic tone regulates ion channel density in a concentration and time dependent manner. The D1R- PKA axis, along with Erk and mTOR are necessary for the persistent increase in LP IA induced by high affinity D1Rs [ABSTRACT FROM AUTHOR]

The spiny lobster, Panulirus interruptus, is a valuable crustacean and most of its production is marketed live. In the northern fisheries of Baja California, Mexico, the animals are exposed to short-term emersion at different air temperatures during the live marketing procedures. This work evaluates the effect of short-term emersion (up to 10 h) at two air temperatures (7ºC and 20ºC) and of a 2-h recovery period on ATP, its related metabolites and some muscle quality parameters. Survival was 100% after all emersion times. No significant differences were found either in the adenylic energetic charge or in the levels of ATP and its related metabolites. The highest concentrations were found for AMP, IMP and INO, while ATP had the lowest levels. Muscle quality parameters such as water holding capacity and shear force remained similar to the control values. Although pH decreased slightly with emersion, it was very close to the control values after the 2-h recovery period. The overall results suggest that P. interruptus may perform physiological compensatory work after 10 h emersion even at 20ºC without significantly affecting the muscle quality.

Neuromodulators alter network output and have the potential to destabilize a circuit. The mechanisms maintaining stability in the face of neuromodulation are not well described. Using the pyloric network in the crustacean stomatogastric nervous system, we show that dopamine (DA) does not simply alter circuit output, but activates a closed loop in which DA-induced alterations in circuit output consequently drive a change in an ionic conductance to preserve a conductance ratio and its activity correlate. DA acted at low affinity type 1 receptors (D1Rs) to induce an immediate modulatory decrease in the transient potassium current (IA) of a pyloric neuron. This, in turn, advanced the activity phase of that component neuron, which disrupted its network function and thereby destabilized the circuit. DA simultaneously acted at high affinity D1Rs on the same neuron to confer activity-dependence upon the hyperpolarization activated current (Ih) such that the DA-induced changes in activity subsequently reduced Ih. This DA-enabled, activity-dependent, intrinsic plasticity exactly compensated for the modulatory decrease in IA to restore the IA:Ih ratio and neuronal activity phase, thereby closing an open loop created by the modulator. Activation of closed loops to preserve conductance ratios may represent a fundamental operating principle neuromodulatory systems use to ensure stability in their target networks. [ABSTRACT FROM AUTHOR]

Measuring neuron capacitance is important for morphological description, conductance characterization, and neuron modeling. One method to estimate capacitance is to inject current pulses into a neuron and fit the resulting changes in membrane potential with multiple exponentials; if the neuron is purely passive, the amplitude and time constant of the slowest exponential give neuron capacitance (Major G, Evans JD, Jack JJ. Biophys J 65: 423-449, 1993). Golowasch et al. (Golowasch J, Thomas G, Taylor AL, Patel A, Pineda A, Khalil C, Nadim F. J Neurophysiol 102: 2161-2175, 2009) have shown that this is the best method for measuring the capacitance of nonisopotential (i.e., most) neurons. However, prior work has not tested for, or examined how much error would be introduced by, slow voltage-dependent phenomena possibly present at the membrane potentials typically used in such work. We investigated this issue in lobster (Panulirus interruptus) stomatogastric neurons by performing current clamp-based capacitance measurements at multiple membrane potentials. A slow, voltage-dependent phenomenon consistent with residual voltage-dependent conductances was present at all tested membrane potentials (95 to 35 mV). This phenomenon was the slowest component of the neuron's voltage response, and failure to recognize and exclude it would lead to capacitance overestimates of several hundredfold. Most methods of estimating capacitance depend on the absence of voltage-dependent phenomena. Our demonstration that such phenomena make nonnegligible contributions to neuron responses even at well-hyperpolarized membrane potentials highlights the critical importance of checking for such phenomena in all work measuring neuron capacitance. We show here how to identify such phenomena and minimize their contaminating influence. [ABSTRACT FROM AUTHOR]

Studies of marine reserves typically focus upon differences in the size and abundance of target organisms inside versus outside reserve borders, but they seldom provide spatially explicit measurements of how reserves influence mortality rates. This study investigated mortality rates for female California spiny lobster (Panulirus interruptus) at multiple sites inside and outside of three marine reserves at the Santa Barbara Channel Islands, California, USA. Mean total mortality (Z) of female lobsters was lower at sites inside reserves (Z = 0.22 [± 0.05 SE]) than at sites outside reserves (Z = 0.59 [± 0.02 SE]). Mean mortality at all sites inside reserves, and among sites near reserve centres (where Z = 0.17 [± 0.05 SE]), was similar to estimates of natural mortality for other temperate spiny lobster species. Among sites inside reserves, there was a positive relationship between mortality and proximity to reserve borders, but this relationship was absent among sites outside reserves. Mortality estimates were much more variable among sites inside reserves than at sites in fished areas. This variation is probably due to differential emigration rates from the three reserves, as well as site-specific ecological factors that influence population structure, demonstrating the importance of spatially explicit reserve sampling and understanding how ecological heterogeneity influences fisheries models. [ABSTRACT FROM PUBLISHER]

The article presents a study on the spiny lobster population and fishery responses to a marine reserve network at Santa Cruz and Santa Rosa Islands in California. The study highlights the application of collaborative fisheries research (CFR), trapping, and analysis of variance (ANOVA) to describe the lobster population and fishery responses. Results show that fish mortality and spillover affects fishery dynamics in islands.

Abstract: A study to determine of the energetic balance of the red spiny lobster Panulirus interruptus juveniles when fed with squid and mussels included dynamic respiratory measurements, determining oxygen consumption, ammonia excretion and calculating the atomic relationship O:N to estimate the metabolic substrate preferred. We concluded that 81.4% of the energy ingested (C) from the mussels was used for growth (P), and 52.4% when squid fed (P<0.001). The eliminated energies (F) of 3.5 with mussels and 3.9% with squid were not significantly different (P>0.05). The nitrogenous excretions (U) were significantly different (P>0.05) with percentage values of 10.8 for mussels, and 1.1% for squid, respectively. The resting oxygen consumptions (R) of 15 and 5.1%, as well as the increase of apparent heat (AHI) of 18.2 and 8.6% were significantly different (P<0.05), for squid and mussels, respectively. A ratio of 5.95 for oxygen-nitrogen (O:N) when squid fed indicates that proteins are used mainly as energetic substrate and consequently were not used in growth. In the case of mussels of ratio 22 it is significantly different (P<0.05), which signifies that proteins mixed with lipids were used as energetic substrate, channeling obviously a part of the proteins for growth, in this case due to its superior nutritious quality. We conclude that the mussels (Mytilus galloprovincialis and M. californicus) as food for juveniles of P. interruptus covers the necessary energetic requirements representing a better food source under laboratory conditions, in aquaculture, and in formulating balanced diets. A survival rate of 100% was obtained during the 221days of the study period. The initial average value of the cephalothorax length (CL) was of 6.91mm, while wet weight was of 0.21g and the final values after eight molts reached the 34.2mm of CL and 35.393g for wet weight; the increase of CL/day was of 0.12mm at 19.4°C. [Copyright &y& Elsevier]

The article discusses a study which examined how behavior and size distribution varied with predation risk in the California spiny lobster Panulirus interruptus in southern California kelp forests. The study measured several factors such as shelter and lobster characteristics, predator density, relative lobster mortality outside of shelter, and quantified lobster antipredator behaviors in the La Jolla Ecological Reserve (LJER) and the Point Loma kelp forest area. It found a much higher predator densities and relative mortality of tethered juvenile and adult lobsters in the LJER than in Point Loma. Findings also indicated that California spiny lobsters modify their antipredatory behaviors with level of predation risk.

Abstract: Large conductance Ca2+-activated potassium (BK) channels play important roles in controlling neuronal excitability. We cloned the PISlo gene encoding BK channels from the spiny lobster, Panulirus interruptus. This gene shows 81–98% sequence identity to Slo genes previously found in other organisms. We isolated a number of splice variants of the PISlo cDNA within Panulirus interruptus nervous tissue. Sequence analysis indicated that there are at least seven alternative splice sites in PISlo, each with multiple alternative segments. Using immunohistochemistry, we found that the PISlo proteins are distributed in the synaptic neuropil, axon and soma of stomatogastric ganglion (STG) neurons. [Copyright &y& Elsevier]

The pyloric network of decapod crustaceans has been intensively studied electrophysiologically in the infraorders Astacidea, Brachyura, and Palinura. The morphology of some or all pyloric neurons has been well described in Astacidea and Brachyura, but less so in Palinura. Given the large evolutionary distance between these three groups, and the large amount of electrophysiology that has been performed in palinuroid species, it is important to fill this gap. We describe here the gross morphology of all six pyloric neuron types in a palinuroid, P. interruptus. All pyloric neurons had complicated, extended dendritic trees that filled the majority of the neuropil, with most small diameter processes present in a shell near the surface of the ganglion. Certain neuron types showed modest preferences for somata location in the ganglion, but these differences were too weak to use as identifying characteristics. Quantitative measurements of secondary branch number, maximum branch order, total process length, and neuron somata diameter were also, in general, insufficient to distinguish among the neurons, although AB and LP neuron somata diameters differed from those of the other types. One neuron type (VD) had a distinctive neurite branching pattern consisting of a small initial branch followed shortly by a bifurcation of the main neurite. The processes arising from these two branches occupied largely non-overlapping neuropil. Electrophysiological recordings showed that each major branch had its own spike initiation zone and that, although the zones fired correlated spikes, they generated spikes independently. VD neurons in the other infraorders have similar morphologies, suggesting that having two arbors is important for the function of this neuron. These data are similar to those previously obtained in Brachyura and Astacidea. It thus appears that, despite their long evolutionary separation, neuron morphology in these three infraorders has not greatly diverged. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The temperature preference of the red spiny lobster, Panulirus interruptus, measured during a 24-h cycle, was characterized by two selected temperatures, one during the light phase (median = 13.3 ± 0.33ºC) and another during the dark phase (median = 15.5 ± 0.54ºC). Both temperatures preferred by the lobsters were significantly different (P < 0.001). The oxygen consumption of the organisms had a bimodal expression, with a median rate of 22.5 mg O2 kg wb–1 h–1 during the day and of 29.4 mg O2 kg wb–1 h–1 during the night. The respiratory rate of the lobsters during the light and dark phases was significantly different (P < 0.0024). The respiratory metabolism was higher during the afternoon and night due to the nomadic movements and food searching activity that the lobsters carry out in their natural habitat.

A fundamental question in systems biology addresses the issue of how flexibility is built into modulatory networks such that they can produce context-dependent responses. Here we examine flexibility in the serotonin (5-HT) response system that modulates the cycle frequency (cf) of a rhythmic motor output. We found that depending on the preparation, the same 5-min bath application of 5-HT to the pyloric network of the California spiny lobster, Panulirus interruptus, could produce a significant increase, decrease, or no change in steady-state cf relative to baseline. Interestingly, the mean circuit output was not significantly different among preparations prior to 5-HT application. We developed pharmacological tools to examine the preparation-to-preparation variability in the components of the 5-HT response system. We found that the 5-HT response system consisted of at least three separable components: a 5-HT2βPan-like component mediated a rapid decrease followed by a sustained increase in cf; a 5-HT1Pan-like component produced a small and usually gradual increase in cf; at least one other component associated with an unknown receptor mediated a sustained decrease in cf. The magnitude of the change in cf produced by each component was highly variable, so that when summed they could produce either a net increase, decrease, or no change in cf depending on the preparation. Overall, our research demonstrates that the balance of opposing components of the 5-HT response system determines the direction and magnitude of 5-HT–induced change in steady-state cf relative to baseline. [ABSTRACT FROM AUTHOR]

Serotonin (5-HT) plays important roles in the maintenance and modulation of neural systems throughout the animal kingdom. The actions of 5-HT have been well characterized for several crustacean model circuits; however, a dissection of the serotonergic transduction cascades operating in these models has been hampered by the lack of pharmacological tools for invertebrate receptors. Here we provide pharmacological profiles for two 5-HT receptors from the swamp crayfish, Procambarus clarkii: 5-HT2 and 5-HT1,. In so doing, we also report the first functional expression of a crustacean 5-HT1 receptor, and show that it inhibits accumulation of CAMP. The drugs mCPP and quipazine are 5-HTI, agonists and are ineffective at 5-HTZB. Conversely, methiothepin and cinanserin are antagonists of 5-HT2@b ut do not block 5-HT1,. A comparison of these two receptors with their orthologs from the California spiny lobster, Panulirus interruptus, indicates conservation of protein tructure, signaling and pharmacology. This conservation extends beyond crustacean infraorders. The signature residues that form the ligand-binding pocket in mammalian 5-HT receptors are found in the crustacean receptors. Similarly, the protein domains involved in G protein coupling are conserved between the two crustacean receptors and other characterized rthropod and mammalian 5-HT receptors. Considering the apparent conservation of pharmacological properties between crustacean 5-HT receptors, these tools could be applicable to related crustacean physiological preparations. [ABSTRACT FROM AUTHOR]

Abstract: Based on data series for 8 consecutive years of settlement of post-larvae of the California spiny lobster Panulirus interruptus, its relationship to commercial catch was examined. The purpose was to establish a database to build a model for prediction of commercial catches of this lobster. The study area is a rocky shelf southwest of the bay entrance of Bahía Tortugas in Baja California Sur. A set of artificial collectors was placed at this site to obtain postpuerulus and early juveniles settlement for each month. Different simple regression analyses were performed on annual series of mean rates of post-larval settlement vs. commercial catches by the Bahía Tortugas fishing cooperative. We tested several delay periods between the series (4–8 years to approximate the age of fishery recruitment) to find the best-fit relationship. The relationship with a 5-year delay showed the highest positive correlation (0.7925) and was statistically significant. This delay period was used to regress the data for the years 1993–2001. The results showed that variations in the abundance of settled post-larvae in a given year are reflected in the commercial catch 5 years later and exhibit the same upward or downward trend. The one exception was the high post-larval settlement rate in 1997–1998, coinciding with the El Niño event, which was not mirrored by a similar increase 5 years later in the 2002–2003 catch. The pre-recruit index seems a very promising tool for predicting catches for this lobster fishery. [Copyright &y& Elsevier]

The dynamic interplay between static and sliding friction is fundamental to many animal movements. One interesting example of stick-slip friction is found in the sound-producing apparatus of many spiny lobster species (Palinuridae). The acoustic movements of the spiny lobster's plectrum over the file are generated by stick-slip friction between the two surfaces. We examined the microscopic anatomy, kinematics, acoustics and frictional properties of the California spiny lobster (Panulirus interruptus) toward the goal of quantitatively characterizing the frictional and acoustic mechanics of this system. Using synchronous high-speed video and sound recordings, we tested whether plectrum kinematics are correlated with acoustic signal features and found that plectrum velocity is positively correlated with acoustic amplitude. To characterize the frictional mechanics of the system, we measured frictional forces during sound production using excised plectrums and files. Similar to rubber materials sliding against hard surfaces, the static coefficient of friction in this system was on average 1.7. The change in the coefficient of friction across each stick-slip cycle varied substantially with an average change of 1.1. Although driven at a constant speed, the plectrum slipped at velocities that were positively correlated with the normal force between the two surfaces. Studies of friction in biological systems have focused primarily on adhesion and movement, while studies of stick-slip acoustics have remained under the purview of musical acoustics and engineering design. The present study offers an integrative analysis of an unusual bioacoustic mechanism and contrasts its physical parameters with other biological and engineered systems. [ABSTRACT FROM AUTHOR]

The spiny lobster, Panulirus interruptus, is a valuable crustacean and most of its production is marketed live. In the northern fisheries of Baja California, Mexico, the animals are exposed to short-term emersion at different air temperatures during the live marketing procedures. This work evaluates the effect of short-term emersion (up to 10 h) at two air temperatures (7°C and 20°C) and of a 2-h recovery period on ATP, its related metabolites and some muscle quality parameters. Survival was 100% after all emersion times. No significant differences were found either in the adenylic energetic charge or in the levels of ATP and its related metabolites. The highest concentrations were found for AMP, IMP and INO, while ATP had the lowest levels. Muscle quality parameters such as water holding capacity and shear force remained similar to the control values. Although pH decreased slightly with emersion, it was very close to the control values after the 2-h recovery period. The overall results suggest that P. interruptus may perform physiological compensatory work after 10 h emersion even at 20°C without significantly affecting the muscle quality. [ABSTRACT FROM AUTHOR]

Identifying reproductive stocks in commercial species is relevant to fishery management strategies. We obtained muscle samples of California spiny lobster ( Panulirus interruptus) from six localities along the west coast of the Baja California Peninsula and analyzed the genetic structure using mtDNA RFLPs. Our results indicated that all localities shared the same major haplotypes and showed a spatial homogeneity in the distribution of haplotype frequencies. An analysis of molecular variance indicated that only 0.84% of the genetic variability was explained by differences among localities and was not significantly different from zero. Weak divergences were found between Bahía Magdalena, the most southerly locality, in relation to other populations. Major oceanographic processes along this coast, combined with a long larval period that supports passive transport among localities, are suggested to explain the results. [ABSTRACT FROM AUTHOR]

Enzymes responsible for digestion of food protein were evaluated and characterized in red lobster (Panulirus interruptus). Several tissues, organs, and body fluids were analyzed. The same composition of proteases was found in gastric juice, midgut gland, and intestinal contents. Using specific substrates and inhibitors, we indentified several isotrypsins and isochymotrypsins by gel electrophoresis. Protease activity was found at pH 3 and reduced by using pepstatin A. Operational variables of enzymes were characterized for management of future studies and potential biotechnologies. Types and activities of lobster digestive enzymes constitute background information to study the digestive abilities of the organism further, and will lead to understanding nutritional needs and feeding ecology, mainly because decapods display unique morphologic, metabolic, and behavioral changes during their life cycle. Also, such enzymes become alternative tools for use in biotechnologies. [ABSTRACT FROM AUTHOR]

We report here the identification of a tachykinin-related peptide (TRP) in crustaceans. Direct MALDI-TOF MS with brain slices of the crayfish Procambarus clarkii indicated the presence of a peptide having an MS number of around 934. Quadrupole orthogonal acceleration time-of-flight (Q-TOF) MS/MS analysis implied the sequence to be APSGFLGMRamide, identical to that of CabTRP Ia, isolated previously from the crab Cancer borealis, and Pev-tachykinin, from the shrimp Penaeus vannamei. The peptide has been shown to be myoactive in the cockroach hindgut, but the structure of its precursor protein had not been elucidated. A cDNA encoding crayfish preproTRP was cloned, revealing that the 225-residue protein contains seven identical copies of the peptide APSGFLGMRamide. This is unique because TRPs identified in other invertebrates were known to exist in several related forms in each species. The conserved structure of TRP in crustaceans was confirmed by cloning preproTRP from the spiny lobster Panulirus interruptus. RT-PCR and Northern blotting analyses suggested that the crayfish preproTRP mRNA is expressed throughout the nervous system, and in situ hybridization studies of the brain revealed that the transcript predominantly localizes to cell clusters 11 (dorsal lateral cells) and 9 (ventral lateral cells). [ABSTRACT FROM AUTHOR]

The stomatogastric nervous system (STNS) is a premiere model for studying modulation of motor pattern generation. Whereas the cellular and network responses to monoamines have been particularly well characterized electrophysiologically, the transduction mechanisms that link the different monoaminergic signals to specific intracellular responses are presently unknown in this system. To begin to elucidate monoaminergic signal transduction in pyloric neurons, we used a bioinformatics approach to predict the existence of 18 monoamine receptors in arthropods, 9 of which have been previously cloned in Drosophila and other insects. We then went on to use the two existing insect databases to clone and characterize the 10th putative arthropod receptor from the spinylobster, Panulirus interruptus. This receptor is most homologous to the 5-HT2 subtype and shows a dose-dependent response to 5-HT but not to any of the other monoamines present in the STNS. Through a series of pharmacological experiments, we demonstrate that this newly described receptor, 5-HT2βPan, couples with the traditional Gq pathway when expressed in HEK293 cells, but not to Gs or GMi/o. Moreover, it is constitutively active, because the highly conserved DRY motif in transmembrane region 3 has evolved into DRF. Site-directed mutagenesis that reverts the motif back to DRY abolishes this agonist-independent activity. We further demonstrate that this receptor most likely participates in the modulation of stomatogastric motor output, because it is found in neurites in the synaptic neuropil of the stomatogastric ganglion as well as in the axon terminals at identified pyloric neuromuscular junctions. [ABSTRACT FROM AUTHOR]

The motor pattern generated by the 14 neurons composing the pyloric circuit in the stomatogastric ganglion (STG) of the spiny lobster, Panulirus interruptus, is organized not only by the synaptic connections between neurons, but also by the characteristic intrinsic electrophysiological properties of the individual cells. These cellular properties result from the unique complement of ion channels that each cell expresses, and the distribution of those channels in the cell membranes. We have mapped the STG expression of shab and shaw, two genes in the Shaker superfamily of potassium channel genes that encode voltage-dependent, non-inactivating channels. Using antibodies developed against peptide sequences from the two channel proteins, we explored the localization and cell-specific expression of the channels. Anti-Shab and anti-Shaw antibodies both stain all the pyloric neurons in the somata, as well as their primary neurites and branch points of large neurites, but to varying degrees between cell types. Staining was weak and irregular (Shaw) or absent (Shab) in the fine neuropil of pyloric neurons, where most synaptic interactions occur. There is a high degree of variability in the staining intensity among neurons of a single cell class. This supports Golowasch et al.''s [J Neurosci 19 (1999) RC33; Neural Comput 11 (1999) 1079] hypothesis that individual cells can have similar firing properties with varying compositions of ionic currents. Both antibodies stain the axons of the peripheral nerves as they enter foregut muscles. We conclude that both Shab and Shaw channels are appropriately localized to contribute to the noninactivating potassium current in the stomatogastric nervous system. [Copyright &y& Elsevier]

The reproductive strategies of the spiny lobster, Panulirus interruptus, in relation to environmental factors (temperature and upwelling) were determined in Baja California during 1989–1999. Two reproductive indices, R1 and R2, are proposed, based on the rate of occurrence of females with spermatophores and ovigerous females, respectively. P. interruptus spawned one brood annually between April and August. The size at which 50% of females were sexually mature was 72.6 mm carapace length (CL), which is well below the current minimum legal size of 82.5 mm CL. Mating and deposition of spermatophores began under moderate sea surface temperature (SST) and low upwelling conditions, but higher rates of deposition were coincident with low SST and strong upwelling. A high value of R1 generally occurred between 12.8 and 16.8 °C, and in general was inversely correlated with winter–spring temperature. Egg-bearing females were present in waters with a temperature range of 12.5–24 °C, and peaked at 14–19.2 °C. Embryonic development and larval hatching coincided with weakening Ekman transport and seasonal ocean warming. Timing of breeding was strongly temperature dependent. El Nin˜o and La Nin˜a condition impacts were particularly evident at the onset and duration of breeding. Warmer temperatures during El Nin˜o periods accelerated breeding significantly, while the contrary happened under cold temperatures during La Nin˜a. Females responded rapidly to declining winter temperatures and began to mate as early as December or as late as February/March. Similarly, oviposition and hatching were accelerated in response to increasing summer temperatures and finished as early as July and as late as September. The relationship between reproduction and the environment suggests that reproductive pattern and larval recruitment are coupled to dominant physical features of the California Current. Since environmental variability impacts on the onset and duration of breeding, the use of flexible management criteria is recommended, in order to guarantee that the opening and closing dates of the fishing season can be adjusted to take account of this unpredictability. This approach, in conjunction with monitoring of reproductive activity, will benefit the fishery by maximising the species’ annual reproductive success. [Copyright &y& Elsevier]

In several systems, including some well studied invertebrate "model" preparations, rapid, rhythmic inputs drive slow muscles. In this situation muscle contractions can summate temporally between motor neuron bursts, tonically contract, and low-pass filter broad-band input. We have investigated how the muscles innervated by each motor neuron type of the rapid, rhythmic (cycle period, ∼ 1 sec) lobster pyloric network respond when driven by previously recorded in vitro pyloric network activity from intact stomatogastric nervous systems. Under these conditions the much slower gastric mill and cardiac sac networks of the stomatogastric nervous system are also active and modify pyloric activity. All of the muscles show pyloric timed phasic contractions that ride on a sustained tonic contraction; muscle activity can range from being almost completely phasic to almost completely tonic. The modifications of pyloric neuron activity induced by gastric mill (cycle period, ∼ 10 sec) activity result in some pyloric muscles showing prominent, gastric mill-timed, changes in either phasic or tonic contraction amplitude. The strong modification of pyloric neuron activity induced by cardiac sac (cycle period, ∼ 60 sec) activity alters the contractions of all pyloric muscles. These changes are sufficient that for some muscles, in some preparations, the primary muscle output is cardiac sac-timed. This is the first work to examine the motor responses of all pyloric muscle classes to spontaneous stomatogastric activity and shows that the pyloric motor pattern is a complex combination of the activities of three neural networks, although only one (the pyloric) innervates the muscles. [ABSTRACT FROM AUTHOR]

Presents a study that examined the cellular defense reaction of the spiny lobster Panulirus interruptus after being inoculated with the sulfated polysaccharide carrageenan. Materials and methods; Results; Discussion.

In order to determine the effect of escape vents in traps used in the California spiny lobster, Panulirus interruptus, fishery along the Pacific coast of Baja California Sur (Mexico), comparative fishing operations were conducted with normal traps and traps modified with escape vents. It was found that carapace height is directly related to trap selectivity. The results show the effectiveness of the vents in allowing sublegal lobsters to escape and in enhancing the catch rate of lobsters with carapace lengths greater than 82.5 mm (minimum legal size). However, the decrease in the number of sublegal lobsters in the modified traps is not as great as expected, since they constitute from 82.6 to 91.6% of the catch, depending on the type of vent and fishing area. This indicates the need to conduct new studies to determine the best type of vent.

Presents information on a study which examined the scaling of acceleratory aquatic locomotion, body size and tail-flip performance of the California spiny lobster, Panulirus interruptus. Materials and methods of the study; Results and discussion.

Negatively stained complexes of Panulirus interruptus (spiny lobster) hemocyania with two different monoclonal antibodies, named E and J, were studied by electron microscopy and image processing. The attachment site of the antibodies to the hexameric hemocyanin molecule was deduced from two perpendicular views of hemocyanin/antibody complexes, in which either the three-fold axis or one of the twofold axes was oriented perpendicular to the supporting film. Images of complexes in these orientations were searched with reference images simulated from the known X-ray structure of P. interruptus hemocyanin. The two sites were further characterized by combining our results from electron microscopy with structural data obtained by X-ray diffraction and other methods. These two antibodies recognize different non-overlapping epitopes. The epitope for clone F, is located on domain 3 at the surface of the β barrel and consists of certain loops, which form connections between β-strand structures. The epitope for clone J is situated on domain 3 at the surface of an α-helical region and consists mainly of certain α-helices connecting loops. The orientation of the hemocyanin hexamers in the two complexes is very different, as is demonstrated most dearly when they form chains, Clone E forms complexes with the threefold axes perpendicular to the chain direction, while for clone J the threefold axes seem to he parallel to the main direction. The angle between the Fab part of an IgG molecule and the threefold axis of the hexamer is 60±5° for clone E and 35±7° for clone J. This observation is clearly related to the difference in orientation of the hexamers for the two complexes. [ABSTRACT FROM AUTHOR]

Electron-microscopic studies revealed that two types of subunits of Panulirus interruptus haemocyanin crystallize in different ways. Homohexamers of subunit a give close-packed two-dimensional crystals whereas homohexamers of subunit c form open two-dimensional arrays. We applied computer-image analysis to these arrays and studied the differences in crystallization properties by combining the electron-microscopic data with amino acid sequence information and the X-ray diffraction model of subunit a. [ABSTRACT FROM AUTHOR]

Single-crystal ultraviolet spectroscopy, X-ray absorption spectroscopy and EPR measurements have been used to examine the oxidation and oxygenation state of the dinuclear copper site of several types of hemocyanin crystals. The crystals contain Panulirus interruptus hemocyanin which forms hexameric molecules with a molecular mass of approximately 470 kDa. Three types of crystals have been investigated. Type-I monoclinic crystals, which have been used for the X-ray structure determination, contain virtually only deoxyhemocyanin. Type-II monoclinic crystals, which are less well ordered than the type-I crystals, contain a mixture of deoxy, oxy and met forms. Older crystals contain relatively more methemocyanin. A third, hexagonal, crystal form is also partially oxygenated, and, like the type-II monoclinic form, subject to gradual conversion to methemocyanin. [ABSTRACT FROM AUTHOR]

As a final step in the elucidation of the primary structure of subunit a of Panulirus interruptus hemocyanin (657 residues, Mr 75696 excluding two copper ions and carbohydrate), the amino acid sequence of the largest fragment obtained by limited trypsinolysis was determined. The elucidation of the sequence of residues 176–657, comprising domains two and three, was mainly based on two digests, with CNBr and trypsin, respectively, from both of which a complete set of peptides was obtained. Additional sequence information was obtained from a digest with Staphylococcus aureus V8 protease and from one fragment obtained by cleaving subunit a with hydroxylamine. A block during Edman degradations indicated an Asn-Gly sequence at positions 597–598, although only aspartic acid was identified at position 597. [ABSTRACT FROM AUTHOR]