Genome-wide CRISPR Screens Reveal Host Factors Critical for SARS-CoV-2 Infection

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Climatic forcing and larval dispersal capabilities shape the replenishment of fishes and their habitat‐forming biota on a tropical coral reef

Fluctuations in marine populations often relate to the supply of recruits by oceanic currents. Variation in these currents is typically driven by large‐scale changes in climate, in particular ENSO (El Nino Southern Oscillation). The dependence on large‐scale climatic changes may, however, be modified by early life history traits of marine taxa. Based on eight years of annual surveys, along 150 km of coastline, we examined how ENSO influenced abundance of juvenile fish, coral spat, and canopy‐forming macroalgae. We then investigated what traits make populations of some fish families more reliant on the ENSO relationship than others. Abundance of juvenile fish and coral recruits was generally positively correlated with the Southern Oscillation Index (SOI), higher densities recorded during La Niña years, when the ENSO‐influenced Leeuwin Current is stronger and sea surface temperature higher. The relationship is typically positive and stronger among fish families with shorter pelagic larval durations and stronger swimming abilities. The relationship is also stronger at sites on the coral back reef, although the strongest of all relationships were among the lethrinids (r = .9), siganids (r = .9), and mullids (r = .8), which recruit to macroalgal meadows in the lagoon. ENSO effects on habitat seem to moderate SOI–juvenile abundance relationship. Macroalgal canopies are higher during La Niña years, providing more favorable habitat for juvenile fish and strengthening the SOI effect on juvenile abundance. Conversely, loss of coral following a La Niña‐related heat wave may have compromised postsettlement survival of coral dependent species, weakening the influence of SOI on their abundance. This assessment of ENSO effects on tropical fish and habitat‐forming biota and how it is mediated by functional ecology improves our ability to predict and manage changes in the replenishment of marine populations.     

Differences between wheat and rice in the enzymic properties of ribulose-1,5-bisphosphate carboxylase/oxygenase and the relationship to photosynthetic gas exchange

The kinetic parameters of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (EC 4.1.1.39) in wheat (Triticum aestivum L.) and rice (Oryza sativa L.) were determined by rapidly assaying the leaf extracts. The respective K _m and V _max values for carboxylase and oxygenase activities were significantly higher for wheat than for rice. In particular, the differences in the V _max values between the two species were greater. When the net activity of CO₂ exchange was calculated at the physiological CO₂-O₂ concentration from these kinetic parameters, it was 22% greater in wheat than in rice. This difference in the in-vitro RuBP-carboxylase/oxygenase activity between the two species reflected a difference in the CO₂-assimilation rate per unit of RuBP-carboxylase protein. However, there was no apparent difference in the CO₂-assimilation rate for a given leaf-nitrogen content between the two species. When the RuBP-carboxylase/oxygenase activity was estimated at the intercellular CO₂ pressure from the enzyme content and kinetic parameters, these estimated enzyme activities in wheat and rice were similar to each other for the same rate of CO₂ assimilation. These results indicate that the difference in the kinetic parameters of RuBP carboxylase between the two species was offset by the differences in RuBP-carboxylase content and conductance for a given leaf-nitrogen content.Abbreviations DTT dithiothreitol - EDTA ethylenediamine-tetraacetic - PAR photosynthetically active radiation - RuBP ribulose-1,5-bisphosphate     

Three unique base pair changes in a family with Gaucher disease

Summary Single-stranded cDNA was prepared from RNA obtained from a patient with type 1 Gaucher disease. The cDNA was amplified in vitro and analyzed by sequencing. Three base-pair changes were identified which included a G to C transversion at nucleotide 3119 of the active gene (Asp¹⁴⁰His), an A to C transversion at nucleotide 3170 (Lys¹⁵⁷Gln) and a G to A change at nucleotide 5309 (Glu³²⁶Lys). To study the mode of inheritance of the three different base-pair changes, genomic DNA was prepared from blood or skin fibroblasts of several family members. Genomic glucocerebrosidase DNA sequences were amplified and subjected to hybridization with allele-specific oligonucleotides (ASOs). The hybridization profiles demonstrated that two of the basepair changes originated from the mother and were transmitted to her two affected sons and to a grandchild, while the third base-pair change, originating from the father, was transmitted to his two affected sons, a carrier daughter and a second grandchild. Tests of other patients with Gaucher disease failed to disclose the presence of the three base-changes. This is a unique family with three base-pair changes tightly linked to Gaucher disease.     

Changes in the Amounts of Ribulose Bisphosphate Carboxylase Synthesized and Degraded during the Life Span of Rice Leaf (Oryza sativa L.)

In situ synthesis and degradation of ribulose bisphosphate carboxylase(RuBPCase) were studied quantitatively in the 12th leaf bladeof the rice plant during the life span of the leaf. Levels ofRuBPCase protein were determined by rocket immunoelectrophoresis.The amounts of RuBPCase synthesized and degraded were estimatedusing ¹⁵N tracer. RuBPCase was scarcely recognized in the leaf when the tip ofthe leaf had just emerged from the 1 lth leaf sheath. Then itincreased rapidly and reached its maximum content a week afterthe completion of leaf expansion. At this time RuBPCase accountedfor 56% of the soluble leaf protein N (26% of the total leafN). The total amount of RuBPCase synthesized up to this timewas about 90% of the amount synthesized throughout the leaf'slife. Degradation of RuBPCase started about the time when it reachedthe maximum content and proceeded at a faster rate during senescencethan that of the remaining soluble protein. When the leaf hadsenesced completely, it contained little measurable RuBPCasealthough the total leaf N was about 30% of the maximum level.These results clearly suggest that RuBPCase is a major N componentwhich is used as remobilized N for the growth of young tissues. Influx and efflux of N and the synthesis and degradation ofRuBPCase are discussed in relation to leaf age. (Received February 18, 1983; Accepted June 16, 1983)     

Enteroviral and Mumps Meningitis in Toronto, 1963

Virological investigations of 115 children with the aseptic meningitis syndrome during 1963 resulted in the isolation of enteroviruses from cerebrospinal fluid (CSF) and/or feces of 21 of 48 children who had no association with mumps. For the third successive year, Echo 9 was the dominant enterovirus in cases of aseptic meningitis in Toronto children, but no rashes were associated with Echo 9 meningitis during 1963, in contradistinction to previous years. Mumps virus was isolated from CSF of 25 patients by inoculation of rhesus monkey kidney cultures, and rising or elevated mumps antihemagglutinin titres in paired sera from a further 33 cases provided laboratory evidence of infection with mumps virus in 58 of 67 patients with mumps meningoencephalitis. No enlargement of salivary glands was noted in 20 laboratory-proved cases of mumps meningoencephalitis. Enteroviral meningitis occurred principally during summer, but the peak of mumps meningoencephalitis occurred during late winter.     

Glutelin accumulation and changes in the levels of its mRNA in the superior and inferior spikelets of rice ear during ripening

Glutelin accumulation in the apical spikelet of the top primary branch (superior spikelet) and the second spikelet of the lowest secondary branch (inferior spikelet) of the ear of the rice plant (Oryza sativa L.) was characterized during grain filling.In the superior spikelet, the accumulation of dry matter and nitrogen started immediately after flowering and rapidly reached the maturation level by 20 days after heading (DAH). At 7 DAH, total RNA content had already reached its maximum level and glutelin mRNA content 70% of its maximum. The increase in glutelin mRNA was followed by a rapid increase in glutelin between 7 and 16 DAH.In the inferior spikelet dry matter, nitrogen and glutelin accumulation were low immediately after flowering and increased only after grain filling of the superior spikelet was almost complete. Total RNA and glutelin mRNA increased much later at slower rates than in the superior spikelet.It is very likely that the retardation of dry matter, total nitrogen and glutelin accumulation in the inferior spikelet is due to retardation of differentiation and development of endosperm tissue, and to glutelin gene expression in endosperm cells. It is suggested that the delayed development resulted from limited partitioning of nutrients to the inferior spikelet at the early stage of ripening.     

Changes in the Content of Two Glutamate Synthase Proteins in Spikelets of Rice (Oryza sativa) Plants during Ripening

Nitrogen accumulation in the apical spikelets on the primary branches of the main stem of rice plants have been studied during the ripening process (0-35 d after flowering). The level of NADH-dependent glutamate synthase (GOGAT) protein and activity increased 4- and 6-fold, respectively, in the first 15 d after flowering. Maximum levels of NADH-GOGAT were found at that time when the spikelets had just begun to increase in dry weight and to accumulate storage proteins. Subsequently, both the level of NADH-GOGAT protein and its activity in spikelets declined rapidly. Although changes in ferredoxin (Fd)-dependent GOGAT paralleled changes in NADH-GOGAT, the relative abundance of NADH-GOGAT protein in the spikelets was about 3 times higher than that of Fd-GOGAT from 5 to 15 d after flowering. When the chaff (lemma and palea) was separated from the spikelets 10 d after the flowering, 16% of the NADH-GOGAT protein was found in the chaff and 84% in the young grain tissues (endosperm, testae, aleurone tissues, and embryo). On the other hand, Fd-GOGAT protein was distributed 52% in the chaff and 48% in the young grain tissues in spikelets of the same age. Activity of NADP-isocitrate dehydrogenase, which may generate the 2-oxoglutarate required for the GOGAT reactions, was much higher than that of total GOGAT activities on a spikelet basis during the ripening process. These results suggest that in rice plants NADH-GOGAT is responsible for the synthesis of glutamate from the glutamine that is transported from senescing tissues to the spikelets.     

1-Acylglycerophosphocholine O-acyltransferase in maturing safflower seeds

The activity of 1-acylglycerophosphocholine (1-acyl-GPC) O-acyltransferase (EC 2.3.1.23) varied during maturation of safflower (Carthamus tinctorius L.) seeds, and activity per seed was highest in the middle period of seed development when triacylglycerol (TAG) is most rapidly synthesized. The specific activity of acyl transfer in a 20000·g particulate preparation exceeded 500nmol·min^-1·(mg protein)^-1 and was higher than those of any other enzymes involved in TAG synthesis (K. Ichihara et al., 1993, Plant Cell Physiol. 34, 557–566). This suggested the presence of a large flux of acyl-CoA to phosphatidylcholine in the cell. The reaction was specific to C₁₆ and C₁₈ acyl-CoAs with a double bond at position 9. Lauroyl- and erucoyl-CoA were completely ineffective, while ricinoleoyl- and elaidoyl-CoA were utilized efficiently. The relative order of specificity for native acyl-CoA species was linoleoyl > oleoyl stearoyl = palmitoyl. When acyl-CoA mixtures were presented, preference for the unsaturated species rather than the saturated species was even more apparent. The enzyme preferentially utilized 1-C₁₆-acyl- and 1-C₁₈-acyl-GPC molecular species, and 1-palmitoyl-, 1-stearoyl-, 1-oleoyl-and 1-linoleoyl-GPC equally served as acyl acceptor. No activity was detected with 1-octanoyl-GPC, and 1-erucoyl-GPC produced little effect. The effectiveness of 1-alkyl-GPC was comparable to that of 1-acyl-GPC. It was thus concluded that the enzyme recognizes the chain lengths of the acyl donor and acceptor, and the double bond at position 9 of the acyl donor.Abbreviations DAG diacylglycerol - DTNB 5,5-dithiobis(2-nitrobenzoic acid) - GP sn-glycerol 3-phosphate - GPC sn-glycero-3-phosphocholine - GPE sn-glycero-3-phosphoethanolamine - GPI sn-glycero-3-phosphoinositol - PC phosphatidylcholine - TAG triacylglycerol