The Cell Cycle Time of CD8+ T Cells Responding In Vivo Is Controlled by the Type of Antigenic Stimulus

A hallmark of cells comprising the mammalian adaptive immune system is the requirement for these rare naïve T (and B) lymphocytes directed to a specific microorganism to undergo proliferative expansion upon first encounter with this antigen. In the case of naïve CD8+ T cells the ability of these rare quiescent lymphocytes to rapidly activate and expand into effector T cells in numbers sufficient to control viral and certain bacterial infections can be essential for survival. In this report we examined the activation, cell cycle time and initial proliferative response of naïve murine CD8+ T cells responding in vivo to Influenza and Vaccinia virus infection or vaccination with viral antigens. Remarkably, we observed that CD8+ T cells could divide and proliferate with an initial cell division time of as short as 2 hours. The initial cell cycle time of responding CD8+ T cells is not fixed but is controlled by the antigenic stimulus provided by the APC in vivo. Initial cell cycle time influences the rate of T cell expansion and the numbers of effector T cells subsequently accumulating at the site of infection. The T cell cycle time varies with duration of the G1 phase of the cell cycle. The duration of G1 is inversely correlated with the phosphorylation state of the retinoblastoma (Rb) protein in the responding T cells. The implication of these findings for the development of adaptive immune responses and the regulation of cell cycle in higher eukaryotic cells is discussed

Pola Pemanenan Buah Tengkawang (Shorea Machrophylla) dan Regenerasi Alaminya di Kebun Masyarakat

Pemungutan buah tengkawang banyak dilakukan masyarakat di populasi alaminya, baik di kebun masyarakat, hutan adat maupun di hutan alam. Kenyataan yang dihadapi sekarang adalah adanya eksploitasi yang mengancam keberadaan pohon penghasil tengkawang. Permasalahan yang kedua adalah apakah selama ini masyarakat memanen biji tengkawang tersebut secara lestari, sehingga kedepannya keberadaan buah tengkawang tetap ada dan berkelanjutan. Penelitian ini bertujuan untuk mendapatkan informasi dari masyarakat tentang cara pemanenan buah, produktivitas pohon dan permudaan yang ada di areal penghasil tengkawang di Kabupaten Sanggau. Metode pengumpulan data di dilapangan yaitu : 1. wawancara dengan pemilik pohon tengkawang; 2. Pembuatan plot pada setiap pohon yang berbuah; 3. Inventarisasi tingkat semai, pancang, tiang dan pohon tengkawang. Hasil penelitian menunjukkan bahwa pemanenan buah tengkawang terjadi pada bulan Desember, Januari, Pebruari dan diperkirakan berakhir di bulan Maret. Masa pembungaannya dimulai pada bulan Nopember, Desember dan Januari. Pemanenan buah tengkawang masih dilakukan secara tradisional. Untuk produksi rata-rata 206,14 kilogram buah/pohon. Untuk tingkat regenerasi alami yang paling banyak ditemukan adalah tingkat semai

Patterns of Coptotermes SP. Termite Attack on Shorea Leprosula Miq in Khdtk Sebulu, East Kalimantan

Red meranti (Shorea leprosula Miq) as a major commercial timber has been widely planted in Dipterocarp forests. Coptotermes sp. termite often attacks S. leprosula Miq to its death, but the attack patterns are unknown. This research aims to get data on the frequency, intensity, and patterns of Coptotermes sp. attack in KHDTK Sebulu, East Kalimantan. Methods used were observation, recording, and mapping on S. leprosula Miq trees attacked by termites in KHDTK Sebulu. The results showed that the frequency of termite attacks on S. leprosula Miq in KHDTK Sebulu was 6.4-30.5% and termite attacks intensity was 4.7-22.1%. Termite attack patterns tended to spread and were followed by the formation of the nest to produce colonies