Drought-Induced Root Pressure in Sorghum bicolor.

Root pressure, also manifested as profusive sap flowing from cut stems, is a phenomenon in some species that has perplexed biologists for much of the last century. It is associated with increased crop production under drought, but its function and regulation remain largely unknown. In this study, we investigated the initiation, mechanisms, and possible adaptive function of root pressure in six genotypes of Sorghum bicolor during a drought experiment in the greenhouse. We observed that root pressure was induced in plants exposed to drought followed by re-watering but possibly inhibited by 100% re-watering in some genotypes. We found that root pressure in drought stressed and re-watered plants was associated with greater ratio of fine: coarse root length and shoot biomass production, indicating a possible role of root allocation in creating root pressure and adaptive benefit of root pressure for shoot biomass production. Using RNA-Seq, we identified gene transcripts that were up- and down-regulated in plants with root pressure expression, focusing on genes for aquaporins, membrane transporters, and ATPases that could regulate inter- and intra-cellular transport of water and ions to generate positive xylem pressure in root tissue.

Morphology and evolution of bioluminescent organs in the glowbellies (Percomorpha: Acropomatidae) with comments on the taxonomy and phylogeny of Acropomatiformes.

Bioluminescent organs have evolved many times within teleost fishes and exhibit a wide range of complexity and anatomical derivation. Although some bioluminescent organs have been studied in detail, the morphology of the bacterial light organs in glowbellies (Acropoma) is largely unknown. This study describes the anatomy of the bioluminescent organs in Haneda's Glowbelly (Acropoma hanedai) and the Glowbelly (Acropoma japonicum) and places the evolution of this light-producing system in the context of a new phylogeny of glowbellies and their relatives. Gross and histological examination of the bioluminescent organs indicate that they are derived from perianal ectodermal tissue, likely originating from the developmental proctodeum, contrary to at least one prior suggestion that the bioluminescent organ in Acropoma is of endodermal intestinal derivation. Additionally, anterior bioluminescent organ development in both species is associated with lateral spreading of the bacteria-containing arms of the bioluminescent organ from an initial median structure. In the context of a 16-gene molecular phylogeny, the bioluminescent organ in Acropoma is shown to have evolved within the Acropomatidae in the ancestor of Acropoma. Further, ancestral-states reconstruction demonstrates that the bioluminescent organs in Acropoma evolved independently from the light organs in related howellid and epigonid taxa which have esophageal or intestinally derived bioluminescent organs. Across the acropomatiforms, our reconstructions indicate that bioluminescent organs evolved independently four or five times. Based on the inferred phylogeny of the order where Acropoma and Doederleinia were separated from other traditional acropomatids, the familial taxonomy of the Acropomatidae was modified such that the previously described Malakichthyidae and Synagropidae were recognized. We also morphologically diagnose and describe the family Lateolabracidae.

Creatine Supplementation Does Not Prevent the Development of Alcoholic Steatosis.

BACKGROUND: Alcohol-induced reduction in the hepatocellular S-adenosylmethionine (SAM):S-adenosylhomocysteine (SAH) ratio impairs the activities of many SAM-dependent methyltransferases. These impairments ultimately lead to the generation of several hallmark features of alcoholic liver injury including steatosis. Guanidinoacetate methyltransferase (GAMT) is an important enzyme that catalyzes the final reaction in the creatine biosynthetic process. The liver is a major site for creatine synthesis which places a substantial methylation burden on this organ as GAMT-mediated reactions consume as much as 40% of all the SAM-derived methyl groups. We hypothesized that dietary creatine supplementation could potentially spare SAM, preserve the hepatocellular SAM:SAH ratio, and thereby prevent the development of alcoholic steatosis and other consequences of impaired methylation reactions. METHODS: For these studies, male Wistar rats were pair-fed the Lieber-DeCarli control or ethanol (EtOH) diet with or without 1% creatine supplementation. At the end of 4 to 5 weeks of feeding, relevant biochemical and histological analyses were performed. RESULTS: We observed that creatine supplementation neither prevented alcoholic steatosis nor attenuated the alcohol-induced impairments in proteasome activity. The lower hepatocellular SAM:SAH ratio seen in the EtOH-fed rats was also not normalized or SAM levels spared when these rats were fed the creatine-supplemented EtOH diet. However, a >10-fold increased level of creatine was observed in the liver, serum, and hearts of rats fed the creatine-supplemented diets. CONCLUSIONS: Overall, dietary creatine supplementation did not prevent alcoholic liver injury despite its known efficacy in preventing high-fat-diet-induced steatosis. Betaine, a promethylating agent that maintains the hepatocellular SAM:SAH, still remains our best option for treating alcoholic steatosis.

The first report of luminescent liver tissue in fishes: evolution and structure of bioluminescent organs in the deep-sea naked barracudinas (Aulopiformes: Lestidiidae).

Bioluminescent organs that provide ventral camouflage are common among fishes in the meso-bathypelagic zones of the deep sea. However, the anatomical structures that have been modified to produce light vary substantially among different groups of fishes. Although the anatomical structure and evolutionary derivation of some of these organs have been well studied, the light organs of the naked barracudinas have received little scientific attention. This study describes the anatomy and evolution of bioluminescent organs in the Lestidiidae (naked barracudinas) in the context of a new phylogeny of barracudinas and closely related alepisauroid fishes. Gross and histological examination of bioluminescent organs or homologous structures from preserved museum specimens indicate that the ventral light organ is derived from hepatopancreatic tissue and that the antorbital spot in Lestrolepis is, in fact, a second dermal light organ. In the context of the phylogeny generated from DNA-sequence data from eight gene fragments (7 nuclear and 1 mitochondrial), a complex liver with a narrow ventral strand running along the ventral midline evolves first in the Lestidiidae. The ventral hepatopancreatic tissue later evolves into a ventral bioluminescent organ in the ancestor of Lestidium and Lestrolepis with the lineage leading to the genus Lestrolepis evolving a dermal antorbital bioluminescent organ, likely for light-intensity matching. This is the first described hepatopancreatic bioluminescent organ in fishes.