KARAKTER MORFOLOGIS DAN PERKEMBANGAN ANATOMIS BIJI MELINJO (Gnetum gnemon L.)

Melinjo seeds (Gnetum gnemon L.) have many benefits, that it is necessary to know its morphological and anatomical characters. This study aimed to determine differences in morphological characters and anatomical development of melinjo seeds at four seed maturity stages. The morphological observation was carried out based on the quantitative and organoleptic characteristics of the melinjo seeds: outer envelope, size, and the color of the middle envelope. Seed development was anatomically observed in slides prepared with a non-embedding method using a sliding microtome then observed through a microscope. The outer seed envelope has a green to blackish-red color in the final stage, while the seed middle envelope has a light-brown to dark-brown in the final stage. The inner seed envelope is thin, non-rigid, and attached on the outside of the endosperm. The seeds' length ranges from ±1,5 cm until ±2,25 cm at the end-stage; seeds width are 1 cm – 1,18 cm; seeds diameter are 1 cm – 1,16 cm. The anatomical development showed tissue thickening and differentiation. The middle envelope is getting thicker: 318,84 μm to 397,29 μm. Endosperm tissue cells undergo cell compaction as the seeds ripen. At the same time, embryonic tissue differentiation forms hypocotyl, epicotyl, and cotyledon.

Evolution of Hepatitis B virus in an acute hepatitis B patient co-infected with genotypes B and C

The interactions between different genotypes of Hepatitis B virus (HBV) in co-infected patients remain largely unknown, especially in acute infection. Here, the evolution of HBV strains was studied in an acute, self-limited hepatitis B patient co-infected with genotypes Ba (B2) and C. Virological analyses were performed at four time points after admission: T1 (5 days), T2 (11 days), T3 (22 days) and T4 (260 days). A dominant-genotype change from genotype C to Ba was found after anti-HBV e antigen (anti-HBe) seroconversion. Further clonal and phylogenetic analyses of the pre-S and pre-core/core regions of HBV were carried out to clarify the interactions between genotypes Ba and C. All clones propagated from T1 and T2 were of genotype C. In contrast, clones propagated from T3 (after anti-HBe seroconversion) were of genotype Ba, C and/or recombinant within the pre-S region. At T4, all clones were of genotype Ba with a 123 bp (from nt 3147 of the pre-S1 region to nt 54 of the pre-S2 region) in-frame pre-S deletion and had lost the start codon of the middle envelope protein and the nucleocapsid-binding site. Phylogenetic analysis showed that genetic distance was greater at T3 after seroconversion to anti-HBe. By using SimPlot, the breakpoint of one pre-S recombinant was located at nt 3069–3100 and the other two at nt 49–87. In conclusion, HBV genotype Ba may overtake genotype C as the predominant strain after anti-HBe seroconversion in acute hepatitis B. Recombination within the pre-S region emerged transiently and the pre-S deletion mutant was finally cleared.

Role for Calnexin and N-Linked Glycosylation in the Assembly and Secretion of Hepatitis B Virus Middle Envelope Protein Particles

ABSTRACT Unlike those of the S and the L envelope proteins, the functional role of the related M protein in the life cycle of the hepatitis B virus (HBV) is less understood. We now demonstrate that a single N glycan, specific for M, is required for efficient secretion of M empty envelope particles. Moreover, this glycan mediates specific association of M with the chaperone calnexin. Conversely, the N glycan, common to all three envelope proteins, is involved neither in calnexin binding nor in subviral particle release. As proper folding and trafficking of M need the assistance of the chaperone, the glycan-dependent association of M with calnexin may thus play a crucial role in the assembly of HBV. Beyond being modified by N glycosylation, M is modified by O glycosylation occurring within its amino acid sequence at positions 27 to 47. The O glycans, however, were found to be dispensable for secretion of M but may rather support viral infectivity. Surprisingly, nonglycosylated M localizes exclusively to the cytosol, either for degradation or for a yet-unknown function.