We report here the discovery of a 3.32 d orbital period in the Supergiant Fast X‐ray Transient (SFXT) source IGR J16479−4514. Using the long‐term light curve of this source obtained with Swift Burst Alert Telescope (BAT) in the energy range of 15–50 keV, we have clearly detected an orbital modulation including a full eclipse of duration ∼0.6 d. In the hard X‐ray band of the BAT instrument, the eclipse ingress and egress are rapid. We have also used the long‐term light curve obtained with the Rossi X‐ray Timing Explorer (RXTE) All Sky Monitor (ASM) in the energy range of 1.5–12 keV. Taken independently, the detection of orbital modulation in the RXTE–ASM light curve is not significant. However, considering a clear detection of orbital modulation in the BAT light curve, we have used the ASM light curve for a more precise determination of the orbital period. IGR J16479−4514 has the shortest orbital period among the three SFXTs with measured/known orbital period. We discuss the implication of a short orbital period with the various mechanisms proposed to explain the transient nature of this class of sources.

Hairy root cultures of Catharanthus roseus var. Prabal were established by infecting the leaves with Agrobacterium rhizogenes agropine-type A4 strain. Two hundred and fifty independent root clones were evaluated for growth, morphology, number of integration of Ri T-DNA genes and alkaloid contents. On the basis of growth pattern, type of branching and number of lateral roots we were able to separate the hairy root clones into four categories. However based on the integration of the Ri T(L)-DNA and T(R)-DNA genes, there were only three different categories of independent hairy root clones-C1 (rolA&B(+)/ags(+)), C2 (rolA&B(-)/ags(+)) and C3 (rolA&B(+)/ags(-)). Southern hybridization analysis revealed both single and multiple copies of T-DNA integration in the root clones. The accumulation of considerable amounts of the root-specific alkaloids ajmalicine and serpentine was observed in the presence of both the T(L)-DNA and T(R)-DNA genes (C1) and the T(L)-DNA gene (C3) alone. Two rolA&B(-) but ags(+) clones (C2) accumulated much less or only very negligible amounts of ajmalicine. The possible role of the T(L)-DNA and T(R)-DNA genes on growth and alkaloid accumulation in these root clones is discussed.

4U 1822−37 is a low mass X‐ray binary (LMXB) system with an accretion disc corona. It is one of the very few LMXBs that shows narrow X‐ray eclipses and small amplitude pulsations of the neutron star. The X‐ray eclipse is an excellent reference for measurement of orbital evolution of the binary, and we have obtained 16 new mid‐eclipse time measurements of this source during the last 13 years using X‐ray observations made with the RXTE‐PCA, RXTE‐ASM, Swift‐XRT, XMM–Newton and Chandra observatories. These, along with the earlier known mid‐eclipse times have been used to accurately determine the time‐scale for a change in the orbital period of 4U 1822−37. We have derived an orbital period Porb= 0.23210887(15) d, which is changing at the rate of d d−1 (at T0= MJD 45614). The time‐scale for a change in the orbital period is of 4.9(1.1) × 106 yr. We also report the detection of 0.59290132(11) s (at T0= MJD 51975) X‐ray pulsations from the source with a long‐term average of −2.481(4) × 10−12  s   s−1, i.e. a spin‐up time‐scale () of 7578(13) yr. In view of these results, we have discussed various mechanisms that could be responsible for the orbital evolution in this system. Assuming the extreme case of conservative mass transfer, we have found that the measured requires a large mass transfer rate of (4.2–5.2) × 10−8  M⊙  yr−1 which together with the spin‐up rate implies a magnetic field strength in the range of (1–3) × 108 G. Using the long‐term RXTE‐ASM light curve, we have found that the X‐ray intensity of the source has decreased over the last 13 yr by ∼40 per cent and there are long‐term fluctuations at time‐scales of about a year. In addition to the long‐term intensity variation, we have also observed significant variation in the intensity during the eclipse. Variation was also seen in the pulse profile, which could be due to changes in the accretion geometry. We briefly discuss the implications of these results on our understanding of the properties of the neutron star and the accretion geometry in this source.

4U 1626−67 is an accretion powered X‐ray pulsar that shows remarkably stable X‐ray luminosity above a time‐scale of hours and gradual intensity variation on a time‐scale of a few years. Unlike the other high magnetic field binary X‐ray pulsars, the spin‐up or spin‐down rate of the neutron star is also very stable on time‐scales up to several years. Here, we report a significant increase in the X‐ray intensity in the long‐term Rossi X‐ray Timing Explorer (RXTE) All Sky Monitor light curve of 4U 1626−67. Similar enhancement in the X‐ray flux has also been detected in the Swift Burst Alert Telescope light curve. The increase in the X‐ray flux took place over a long period of about 100 d and there appear to be two episodes of flux enhancement. We have investigated the spectral and timing features of 4U 1626−67 during its current state of enhanced flux emission with data obtained from the Proportional Counter Array and the High‐Energy X‐ray Timing Explorer on board RXTE. We report the detection of a torque reversal to spin‐up in 4U 1626−67. The source has entered a new spin‐up phase with a spin‐up rate of 4.02(5) × 10−13 Hz s−1. The present spin‐up rate is almost half of the earlier spin‐up and spin‐down trends. A significant excess in soft X‐ray photon emission is observed during the enhanced flux state, which is similar to the energy spectrum obtained during the spin‐up era of the pulsar before 1990. 4U 1626−67 is a unique accretion powered X‐ray pulsar in which quasi‐periodic oscillations have been consistently observed over the past ∼20 years. During the recent observations, however, we did not detect a quasi‐periodic oscillation at frequencies as seen in earlier observations. Instead, we report detection of a significant broadening in the wings of the 130 mHz peak and a change in the shape of the continuum of the power spectrum. These results indicate that the flux enhancement is not a simple case of increased mass accretion rate, but there is also a change in the accretion geometry in the vicinity of the neutron star.