Attention in visually typical and amblyopic children.

Amblyopia is a cortical visual disorder caused by unequal visual input to the brain from the two eyes during development. Amblyopes show reduced visual acuity and contrast sensitivity and abnormal binocularity, as well as more "global" perceptual losses, such as figure-ground segregation and global form integration. Currently, there is no consensus on the neural basis for these higher-order perceptual losses. One contributing factor could be that amblyopes have deficiencies in attention, such that the attentional processes that control the selection of information favor the better eye. Previous studies in amblyopic adults are conflicting as to whether attentional deficits exist. However, studies where intact attentional ability has been shown to exist were conducted in adults; it is possible that it was acquired through experience. To test this hypothesis, we studied attentional processing in amblyopic children. We examined covert endogenous attention using a classical spatial cueing paradigm in amblyopic and visually typical 5- to 10-year old children. We found that all children, like adults, independently of visual condition, benefited from attentional cueing: They performed significantly better on trials with an informative (valid) cue than with the uninformative (neutral) cue. Response latencies were also significantly shorter for the valid cue condition. No statistically significant difference was found between the performance of the amblyopic and the visually typical children or between dominant and nondominant eyes of all children. The results showed that covert spatial attention is intact in amblyopic and visually typical children and is therefore not likely to account for higher-order perceptual losses in amblyopic children.

Effects of size and sex on the courting success and foraging behaviour of Embiotoca jacksoni.

To test life-history theory that body size and sex should influence how animals allocate time to foraging versus reproductive activities, we measured the effects of size and sex on courting success and foraging behaviour of black surfperch Embiotoca jacksoni off Santa Catalina Island, southern California. Observations of focal fish were made while snorkelling, during which the length of each fish (estimated to the nearest cm), total duration of courting encounters and foraging rates were recorded. We made observations during and outside the mating season. Courtship occurred only between pairs and its duration increased with the size of both the male and female. Although males would court females that were smaller or larger than themselves, pairs that were closely matched in size had long courting sessions, whereas those that differed considerably in size courted only briefly. Small fish foraged more than larger fish, both during and outside the mating season. Males and females foraged at similar rates outside of the mating season, but during the mating season males reduced their foraging rates to less than half that seen outside of the mating season, whereas females continued to forage at the same rate. This decrease in foraging rate of males during the mating season was seen in all sizes of males but was proportionally greatest in the largest males. These observations indicate that males trade off time spent on foraging for time spent courting during the mating season, whereas females do not.

Reproductive behaviour and concurrent sound production of Gulf grouper Mycteroperca jordani (Epinephelidae) at a spawning aggregation site.

The reproductive and acoustic behaviours of Gulf grouper Mycteroperca jordani were studied at a spawning aggregation site in the southern Gulf of California, México. In May 2015-2017, divers located and surveyed a spawning aggregation site within Cabo Pulmo National Park. Adult M. jordani conformed to a lek mating system in which large males formed territories over sand adjacent to a rocky reef that were spatially segregated from smaller females outside of courtship and spawning periods. Females moved into male territories during evening hours to spawn. Male courtship behaviours targeted a single female, included head shakes and burst rises and preceded pair spawning prior to sunset. Males and females displayed three shared colour phases, but four phases were sex-specific. During evening hours, courtship and spawning, both sexes exhibited sexual dichromatism concurrent with reproductive behaviours. The pair-spawning mating system and observations of bimodal size distributions by sex support previous claims of protogyny in the species. Males produced sounds during territorial patrols, courtship and spawning rushes, which corroborated the importance of acoustic communication within the behavioural repertoire associated with spawning. Long-term acoustic monitoring revealed increases in total sounds detected day-1 from March through June with diel increases (e.g., evenings) that may be indicative of the spawning season. Observations of spawning on 12 consecutive evenings in May 2017 coupled with extended periods of sound production suggest that spawning does not follow a lunar rhythm. This first description of the mating system and sounds of the endangered M. jordani facilitates future development of seasonal and areal protections to restore and manage the species.

Distribution, behavior, and condition of herbivorous fishes on coral reefs track algal resources.

Herbivore distribution can impact community structure and ecosystem function. On coral reefs, herbivores are thought to play an important role in promoting coral dominance, but how they are distributed relative to algae is not well known. Here, we evaluated whether the distribution, behavior, and condition of herbivorous fishes correlated with algal resource availability at six sites in the back reef environment of Moorea, French Polynesia. Specifically, we tested the hypotheses that increased algal turf availability would coincide with (1) increased biomass, (2) altered foraging behavior, and (3) increased energy reserves of herbivorous fishes. Fish biomass and algal cover were visually estimated along underwater transects; behavior of herbivorous fishes was quantified by observations of focal individuals; fish were collected to assess their condition; and algal turf production rates were measured on standardized tiles. The best predictor of herbivorous fish biomass was algal turf production, with fish biomass increasing with algal production. Biomass of herbivorous fishes was also negatively related to sea urchin density, suggesting competition for limited resources. Regression models including both algal turf production and urchin density explained 94 % of the variation in herbivorous fish biomass among sites spread over ~20 km. Behavioral observations of the parrotfish Chlorurus sordidus revealed that foraging area increased as algal turf cover decreased. Additionally, energy reserves increased with algal turf production, but declined with herbivorous fish density, implying that algal turf is a limited resource for this species. Our findings support the hypothesis that herbivorous fishes can spatially track algal resources on coral reefs.

Esotropia associated with high myopia.

PURPOSE OF REVIEW: The aim of the present article is to describe the pathophysiology of esotropia associated with high myopia, commonly known as heavy eye syndrome, and discuss the preoperative evaluation and surgical options in these complex patients. RECENT FINDINGS: Numerous studies have looked to determine the cause of esotropia in patients with high myopia. Orbital imaging has shown a nasal displacement of the superior rectus muscle and an inferior displacement of the lateral rectus muscle. As such, traditional resection-recession surgery can be ineffective in these patients. Instead, correcting the deviant muscles paths is necessary. Recent studies have shown that loop myopexy with or without medial rectus recession can be performed without sclera fixation sutures to correct the underlying pathophysiology. SUMMARY: Heavy eye syndrome or strabismus fixus is a rare restrictive strabismus. Careful preoperative evaluation must be performed in order to correctly diagnose these patients. If posterior globe prolapse with superior and lateral rectus muscle displacement is seen, loop myopexy can be a well tolerated and effective procedure in treating heavy eye syndrome.

High population density enhances recruitment and survival of a harvested coral reef fish.

A negative relationship between population growth and population density (direct density dependence) is necessary for population regulation and is assumed in most models of harvested populations. Experimental tests for density dependence are lacking for large-bodied, harvested fish because of the difficulty of manipulating population density over large areas. We studied a harvested coral reef fish, Lutjanus apodus (schoolmaster snapper), using eight large, isolated natural reefs (0.4-1.6 ha) in the Bahamas as replicates. An initial observational test for density dependence was followed by a manipulation of population density. The manipulation weakened an association between density and shelter-providing habitat features and revealed a positive effect of population density on recruitment and survival (inverse density dependence), but no effect of density on somatic growth. The snappers on an individual reef were organized into a few shoals, and we hypothesize that large shoals on high-density reefs were less vulnerable to large piscivores (groupers and barracudas) than the small shoals on low-density reefs. Reductions in predation risk for individuals in large social groups are well documented, but because snapper shoals occupied reefs the size of small marine reserves, these ecological interactions may influence the outcome of management actions.

Aberrant epigenetic silencing of neuronatin is a frequent event in human osteosarcoma.

The paternally imprinted neuronatin (NNAT) gene has been identified as a target of aberrant epigenetic silencing in diverse cancers, but no association with pediatric bone cancers has been reported to date. In screening childhood cancers, we identified aberrant CpG island hypermethylation in a majority of osteosarcoma (OS) samples and in 5 of 6 human OS cell lines studied but not in normal bone-derived tissue samples. CpG island hypermethylation was associated with transcriptional silencing in human OS cells, and silencing was reversible upon treatment with 5-aza-2'-deoxycytidine. Expression of NNAT was detectable in osteoblasts and chondrocytes of human bone, supporting a potential role in bone homeostasis. Enforced expression of NNAT in human OS cells lacking endogenous expression resulted in significant reduction in colony formation and in vitro migration compared to nonexpressor control cells. We next analyzed the effect of NNAT expression on intracellular calcium homeostasis and found that was associated with an attenuated decay of calcium levels to baseline following ATP-induced release of calcium from endoplasmic reticulum (ER) stores. Furthermore, NNAT expression was associated with increased cytotoxicity in OS cells from thapsigargin, an inhibitor of calcium reuptake into ER and an inducer of the ER stress response. These results suggest a possible tumor suppressor role for NNAT in human osteosarcoma. Additional study is needed ascertain sensitization to ER stress-associated apoptosis as a mechanism of NNAT-dependent cytotoxicity. In that case, epigenetic modification therapy to effect NNAT transcriptional derepression may represent a therapeutic strategy potentially of benefit to a majority of osteosarcoma patients.

Inter-cohort competition drives density dependence and selective mortality in a marine fish.

For organisms with complex life cycles, the transition between life stages and between habitats can act as a significant demographic and selective bottleneck. In particular, competition with older and larger conspecifics and heterospecifics may influence the number and characteristics of individuals successfully making the transition. We investigated whether the availability of enemy-free space mediated the interaction between adult goldspot gobies (Gnatholepis thompsoni), a common tropical reef fish, and juvenile conspecifics that had recently settled from the plankton. We added rocks, which provide refuge from predators, to one-half of each of five entire coral reefs in the Bahamas and measured the survival and growth of recent settlers in relation to adult goby densities. We also evaluated whether mortality was selective with respect to three larval traits (age at settlement, size at settlement, and presettlement growth rate) and measured the influence of refuge availability and adult goby density on selection intensity. Selective mortality was measured by comparing larval traits of newly settled gobies (< or = 5 d postsettlement) with those of survivors (2-3 week postsettlement juveniles). We detected a negative relationship between juvenile survival and adult goby density in both low- and high-refuge habitats, though experimental refuge addition reduced the intensity of this density dependence. Juvenile growth also declined with increasing adult goby density, but this effect was similar in both low- and high-refuge habitats. Refuge availability had no consistent effect on selective mortality, but adult goby density was significantly related to the intensity of size-selective mortality: bigger juveniles were favored where adults were abundant, and smaller juveniles were favored where adults were rare. Given the typically large difference in sizes of juveniles and adults, similar stage-structured interactions may be common but underappreciated in many marine species.

Musical chairs mortality functions: density-dependent deaths caused by competition for unguarded refuges.

Structural refuges within which prey can escape from predators can be an important limiting resource for the prey. In a manner that resembles the childhood game of musical chairs, many prey species rapidly retreat to shared, unguarded refuges whenever a predator threatens, and only when refuges are relatively abundant do all prey individuals actually escape. The key feature of this process is that the per capita prey mortality rate depends on the ratio of prey individuals to refuges. We introduce a new class of mortality functions with this feature and then demonstrate statistically that they describe field mortality data from a well-studied coral reef fish species, the Caribbean bridled goby Coryphopterus glaucofraenum, substantially better than do several mortality functions of more conventional form.

The Role of Superior Oblique Posterior Tenectomy Along With Inferior Rectus Recessions for the Treatment of Chin-up Head Positioning in Patients With Nystagmus.

PURPOSE: To evaluate the clinical outcomes of bilateral superior oblique posterior 7/8th tenectomy with inferior rectus recession on improving chin-up head positioning in patients with horizontal nystagmus. METHODS: Medical records were reviewed from 2007 to 2017 for patients with nystagmus and chin-up positioning of 15° or more who underwent combined bilateral superior oblique posterior 7/8th tenectomy with an inferior rectus recession of at least 5 mm. RESULTS: Thirteen patients (9 males and 4 females) were included, with an average age of 7.3 years (range: 1.8 to 15 years). Chin-up positioning ranged from 15° to 45° degrees (average: 30°). Three patients had prior horizontal muscle surgeries, 1 for esotropia and 2 for horizontal null zones causing anomalous face turns. Ten patients underwent other concomitant eye muscle surgery: 3 had esotropia, 1 had exotropia, and 2 had biplanar nystagmus null point requiring a horizontal Anderson procedure. Four patients underwent simultaneous bilateral medial rectus tenotomy and reattachment. All patients had improved chin-up positioning. Eight patients had complete resolution, whereas 5 had minimal residual chin-up positioning. Three patients developed an eccentric horizontal gaze null point with compensatory anomalous face turn with onset 2 weeks, 2 years, and 3 years postoperatively. Average follow-up was 42.7 months. No postoperative pattern deviations, cyclodeviations, or inferior oblique overaction were seen. No surgical complications were noted. CONCLUSIONS: Bilateral superior oblique posterior 7/8th tenectomy in conjunction with bilateral inferior rectus recession is a safe and effective procedure for improving chin-up head positioning in patients with horizontal nystagmus with a down gaze null point. [J Pediatr Ophthalmol Strabismus. 2018;55(4):234-239.].

The relative importance of predation and competition in two reef fishes.

Competition and predation may both strongly influence populations of reef fishes, but the importance of these processes relative to one another is poorly understood. I quantified the effects of predation and competition on the growth and survival of two temperate reef fishes, Lythrypnus dalli and Coryphopterus nicholsii, in field experiments in which I manipulated the densities of the two species and the abundance of predators (using exclosure cages) on small replicate patch reefs. I also evaluated the influence of predators on the behavior of the two species to help interpret the mechanisms of any predatory influences on growth or survival. Predation was much more important than competition (inter- or intraspecific) in Lythrypnus. For Coryphopterus, neither competition nor predation were particularly important. Behaviorally, both species responded to predators by reducing foraging rate and hiding. This altered behavior, however, had no repercussions for growth or survival of Coryphopterus. In contrast, Lythrypnus grew more slowly and suffered greater mortality when exposed to predators. Interspecific competition did not significantly influence either species. Intraspecific competition did not affect the growth of Coryphopterus, but survival tended to be lower at high densities. Growth of Lythrypnus was depressed by intraspecific competition, but survival was not, except that, in the presence of predators, survival was density dependent. In contrast to the historical emphasis placed on the role of competition, this study indicates that predation can be more important than competition in determining patterns of abundance of some reef fishes. For example, predators not only influenced foraging of both Lythrypnus and Coryphopterus, but they also reduced growth and survival of Lythrypnus, and therefore appear to help maintain the marked habitat segregation between the two species.

Growth of estuarine fish is associated with the combined concentration of sediment contaminants and shows no adaptation or acclimation to past conditions.

We tested whether the growth rates of small benthic fish (Gillichthys mirabilis) in three southern California estuaries corresponded with the local concentrations of contaminants. Fish originating from each estuary were transplanted to cages in each estuary in two reciprocal transplant experiments. The growth rates of caged fish, and the size-distribution of natural populations, showed the same pattern of difference among estuaries. Twelve metals and organic contaminants occurred in bulk sediments at concentrations close to their individual ERL values, and a simple index of their combined concentration (the mean ERL quotient) was inversely correlated to the growth of caged fish. Metals in the water column occurred at lower concentrations, relative to toxicity thresholds, than those in sediments and were unrelated to fish growth. Fish used in the field caging experiments, and other fish held in the laboratory under constant conditions, showed no difference in growth according to their estuary of origin. Fish originating from different estuaries also showed no consistent differences in their tissue burden of organic contaminants. Our results thus suggested no genetic adaptation or physiological acclimation to the past contaminant regime, but revealed a possible association between fish growth rates and the combined concentration of multiple sediment contaminants.

Bilateral posterior tenectomy of the superior oblique muscle for the treatment of A-pattern strabismus.

PURPOSE: To evaluate the efficacy of bilateral posterior superior oblique tenectomy for the treatment of A-pattern strabismus due to superior oblique overaction regardless of the magnitude of the pattern. METHODS: The medical records of patients with A-pattern esotropia or exotropia in the presence of superior oblique overaction who underwent combined horizontal muscle surgery along with bilateral superior oblique posterior 7/8 tenectomy from 2003 to 2013 were retrospectively reviewed. Patients with at least 3 months' follow-up were included. RESULTS: A total of 73 patients were included. Of these, 46 had esotropia; 27, exotropia. The preoperative A-pattern deviation for the study population was 19.6(Δ) ± 11.4(Δ) (range, 10-60), with a final postoperative patten collapse of 18.2 ± 3.6. Superior oblique overaction was 2.3 ± 0.7 preoperatively and 0.3 ± 0.7 postoperatively. Overall, 87.7% of patients had a successful collapse of their pattern to <10(Δ) following the initial bilateral superior oblique posterior tenectomy, with an additional 4.1% following a second procedure. Of patients with a pattern deviation of <25(Δ), 87.9% had successful collapse of the pattern following 1 surgery, and 86.7% of patients who had a pattern of ≥25(Δ) had successful collapse. Postoperatively, 7 patients demonstrated mild inferior oblique overaction. No surgical complications were noted. CONCLUSIONS: A uniform dose of bilateral posterior 7/8 tenectomy surgery successfully collapses A-pattern deviations of all magnitudes.

Recent region-wide declines in Caribbean reef fish abundance.

Profound ecological changes are occurring on coral reefs throughout the tropics, with marked coral cover losses and concomitant algal increases, particularly in the Caribbean region. Historical declines in the abundance of large Caribbean reef fishes likely reflect centuries of overexploitation. However, effects of drastic recent degradation of reef habitats on reef fish assemblages have yet to be established. By using meta-analysis, we analyzed time series of reef fish density obtained from 48 studies that include 318 reefs across the Caribbean and span the time period 1955-2007. Our analyses show that overall reef fish density has been declining significantly for more than a decade, at rates that are consistent across all subregions of the Caribbean basin (2.7% to 6.0% loss per year) and in three of six trophic groups. Changes in fish density over the past half-century are modest relative to concurrent changes in benthic cover on Caribbean reefs. However, the recent significant decline in overall fish abundance and its consistency across several trophic groups and among both fished and nonfished species indicate that Caribbean fishes have begun to respond negatively to habitat degradation.

SPATIAL DENSITY DEPENDENCE SCALES UP BUT DOES NOT PRODUCE TEMPORAL DENSITY DEPENDENCE IN A REEF FISH.

Field experiments provide rigorous tests of ecological hypotheses but are typically of short duration and use small spatial replicates. We assessed empirically whether the results of experiments testing for density dependence applied at larger spatial domains and explained temporal population dynamics. We studied a small coral reef fish, the goldspot goby (Gnatholepis thompsoni), in the Bahamas. We assessed the effects of interactions with conspecifics and with an ecologically similar species, the bridled goby (Coryphopterus glaucofraenum). Two density manipulations on small reef patches revealed that goldspot goby mortality over one month increased as conspecifics became crowded. On five large natural reefs, we correlated the initial year-class density of both species (annual larval settlement) with the subsequent decline of goldspot goby year-classes for five years. Mortality was correlated with conspecific density among reefs for all years, but not among years for all reefs. Thus, spatial density dependence in mortality scaled up qualitatively from small patches to entire reefs but was not associated with temporal density dependence. Our results support the conclusion that field experiments may be extrapolated to larger spatial domains with care, but that using small spatial comparisons to predict temporal responses is difficult without knowing the underlying biological mechanisms.

Assessing the magnitude of intra- and interspecific competition in two coral reef fishes.

Many field experiments have tested for effects of competition in nature, but relatively few have used designs allowing simultaneous assessment of the influence of intra- and interspecific competition. Using a response surface design and a press manipulation of densities, we tested effects of competition within and between two species of coral reef fishes (Coryphopterus glaucofraneum and Gnatholepis thompsoni). By tracking individually tagged fishes, we showed that the per-capita effect of intraspecific competitors on individual growth was at least twice as great as the effect of interspecific competitors. Growth rate was better predicted by measures of density that incorporated body size, rather than numerical density, suggesting interference competition. Individuals of both species interacted aggressively with conspecifics at least twice as often as with heterospecifics. Individuals of both species also covered more area while foraging and spent less time in shelter when crowded than when at lower densities. In combination, these behaviours suggest that increased metabolic costs at high density contribute to competitive effects on growth. These competitive interactions occurred among adult fishes, so reduced growth may translate to reduced fecundity as well as reduced survival, and so contribute to population regulation.

Axillary cannulation for proximal aortic surgery is as safe in the emergent setting as in elective cases.

BACKGROUND: Right axillary artery cannulation and selective antegrade cerebral perfusion (SCP) have become well-described strategies in the surgical treatment of proximal aortic disease. Many series report increases in adverse outcomes with SCP used in emergent settings. We compare outcomes in elective and emergent patients. METHODS: Over 21 months, SCP through right axillary cannulation with a side graft was performed in 61 patients. Thirty-three percent (20 of 61) underwent emergent operation for Stanford type A dissection or intramural hematoma, including 3 of 20 (4.7%) with pericardial tamponade; the remainder of SCP (41 of 61) was elective. The mean follow-up was 9.1 +/- 0.40 months. RESULTS: Selective antegrade cerebral perfusion was used in 20 of 22 emergent cases (91%), with 2 unsuccessful cannulation attempts, and no peripheral arterial dissections encountered. The SCP flows averaged 16.3 +/- 0.71 cc x kg(-1) x min(-1) for a mean perfusion period of 26.1 +/- 1.9 minutes. The average cardiopulmonary bypass time for all patients was 173 +/- 11 minutes. Average hospital stay was 8.1 +/- 0.80 days. One case (1.3%) of permanent and 3 cases (4.8%) of temporary neurologic dysfunction occurred in SCP patients. The hospital mortality rate for emergent SCP cases (2 of 20, 10%) was not statistically different from the mortality rate for elective SCP cases (3 of 41, 7.3%, p = not significant), with no difference in complication rates. All 3 SCP patients with preoperative tamponade survived without complication. Cerebral oximetry data showed a trend toward decreased left-sided (contralateral) scalp perfusion. There was no association of emergent status with neurologic dysfunction, death, or any other adverse outcome. CONCLUSIONS: Axillary cannulation and SCP in the surgical treatment of proximal aortic pathology is safe in both elective and emergent settings.

Small-scale field experiments accurately scale up to predict density dependence in reef fish populations at large scales.

Field experiments provide rigorous tests of ecological hypotheses but are usually limited to small spatial scales. It is thus unclear whether these findings extrapolate to larger scales relevant to conservation and management. We show that the results of experiments detecting density-dependent mortality of reef fish on small habitat patches scale up to have similar effects on much larger entire reefs that are the size of small marine reserves and approach the scale at which some reef fisheries operate. We suggest that accurate scaling is due to the type of species interaction causing local density dependence and the fact that localized events can be aggregated to describe larger-scale interactions with minimal distortion. Careful extrapolation from small-scale experiments identifying species interactions and their effects should improve our ability to predict the outcomes of alternative management strategies for coral reef fishes and their habitats.