Search

Mixotrophic protists combine photosynthesis and phagotrophy to obtain energy and nutrients. Because mixotrophs can act as either primary producers or consumers, they have a complex role in marine food webs and biogeochemical cycles. Many mixotrophs are also phenotypically plastic and can adjust their metabolic investments in response to resource availability. Thus, a single species's ecological role may vary with environmental conditions. Here, we quantified how light and food availability impacted the growth rates, energy acquisition rates, and metabolic investment strategies of eight strains of the mixotrophic chrysophyte, Ochromonas. All eight Ochromonas strains photoacclimated by decreasing chlorophyll content as light intensity increased. Some strains were obligate phototrophs that required light for growth, while other strains showed stronger metabolic responses to prey availability. When prey availability was high, all eight strains exhibited accelerated growth rates and decreased their investments in both photosynthesis and phagotrophy. Photosynthesis and phagotrophy generally produced additive benefits: In low‐prey environments, Ochromonas growth rates increased to maximum, light‐saturated rates with increasing light but increased further with the addition of abundant bacterial prey. The additive benefits observed between photosynthesis and phagotrophy in Ochromonas suggest that the two metabolic modes provide nonsubstitutable resources, which may explain why a tradeoff between phagotrophic and phototrophic investments emerged in some but not all strains. [ABSTRACT FROM AUTHOR]

The revolution and acceleration in DNA sequencing over the past three decades has driven the development of new biomolecular tools like environmental DNA (eDNA) metabarcoding for characterizing marine biodiversity. In order to operationalize eDNA approaches for routine NOAA observatories, new bioinformatic programs and improved organismal reference barcodes are needed to provide accurate and reliable biological data in a timely manner. To address these needs, we present Rapid Exploration and Visualization through an Automated Metabarcoding Pipeline (REVAMP), which provides streamlined end-to-end data processing from raw reads to data exploration, visualization, and hypothesis generation. One benefit of REVAMP is the ability to iteratively assess marker gene and reference database performance. Here, we used a filtered reference database that only included sequences uploaded prior to specified date cutoffs from 1995 to 2022 to analyze changes in eDNA metabarcoding taxonomic assignments, revealing patterns of uneven improvement in taxonomic assignment depth and accuracy across time, region, and marker sets. This work highlights the need for targeted reference sequencing efforts for key regional taxa and the importance of such efforts for improving eDNA biomonitoring approaches in the future. [ABSTRACT FROM AUTHOR]

The phylum Apicomplexa is a quintessentially parasitic lineage, whose members infect a broad range of animals. One exception to this may be the apicomplexan genus Nephromyces, which has been described as having a mutualistic relationship with its host. Here we analyze transcriptome data from Nephromyces and its parasitic sister taxon, Cardiosporidium, revealing an ancestral purine degradation pathway thought to have been lost early in apicomplexan evolution. The predicted localization of many of the purine degradation enzymes to peroxisomes, and the in silico identification of a full set of peroxisome proteins, indicates that loss of both features in other apicomplexans occurred multiple times. The degradation of purines is thought to play a key role in the unusual relationship between Nephromyces and its host. Transcriptome data confirm previous biochemical results of a functional pathway for the utilization of uric acid as a primary nitrogen source for this unusual apicomplexan. [ABSTRACT FROM AUTHOR]

Egg masses of ommastrephid squids are rarely found and not well studied. For the Humboldt squid,Dosidicus gigas, only a single egg mass has been scientifically documented in the wild. Little is known about the size and spatial or temporal distribution of egg masses, or the number of eggs they contain. In this study, we report observations of six egg masses laid in the Gulf of California in May 2015. Egg mass diameters were two to four times smaller in this study compared with the previously observed mass reported in 2008, consistent with the small and large sizes, respectively, of mature female squid captured during each study. Each egg mass contained 17,000–90,000 embryos, one to two orders of magnitude lower than that estimated for the large egg mass previously observed. Egg masses were observed at 9–14 m depth on or near a thermocline. Developmental stages of embryos and paralarvae differed between egg masses. No egg masses were observed in the 13 dives before or the four dives after these masses were found, suggesting that female spawning activity is probably spatially, or perhaps temporally, patchy. Developmental heterochronies in chromatophore development betweenD. gigasand other ommastrephid squids are discussed. Amphipods and ciliates infested the majority of masses, which is the first documented case of biota associated with wild ommastrephid egg masses. [ABSTRACT FROM AUTHOR]

When Drosophila melanogaster larvae are reared on isocaloric diets differing in their amounts of protein relative to sugar, emerging adults exhibit significantly different development times and metabolic pools of protein, glycogen and trigylcerides. In the current study, we show that the influence of larval diet experienced during just one generation extends into the next generation, even when that subsequent generation had been shifted to a standard diet during development. Offspring of flies that were reared on high protein relative to sugar underwent metamorphosis significantly faster, had higher reproductive outputs, and different metabolic pool contents compared to the offspring of adults from low protein relative to sugar diets. In addition, isofemale lines differed in the degree to which parental effects were observed, suggesting a genetic component to the observed transgenerational influences. [ABSTRACT FROM AUTHOR]

When Drosophila melanogaster larvae are reared on isocaloric diets differing in their amounts of protein relative to sugar, emerging adults exhibit significantly different development times and metabolic pools of protein, glycogen and trigylcerides. In the current study, we show that the influence of larval diet experienced during just one generation extends into the next generation, even when that subsequent generation had been shifted to a standard diet during development. Offspring of flies that were reared on high protein relative to sugar underwent metamorphosis significantly faster, had higher reproductive outputs, and different metabolic pool contents compared to the offspring of adults from low protein relative to sugar diets. In addition, isofemale lines differed in the degree to which parental effects were observed, suggesting a genetic component to the observed transgenerational influences. [ABSTRACT FROM AUTHOR]