Distribution and conservation of the Gaur Bos gaurus in the Indian Subcontinent

The Gaur Bos gaurus ranges from India to peninsular Malaysia. Its distribution, status and conservation in the Indian subcontinent are reviewed here on the basis of available information, both published papers and unpublished census reports of forest departments, and field survey data from north‐eastern India and parts of Bhutan and Nepal. The Gaur is found in three disjunct regions, south‐western India, central India and north‐eastern India (including Nepal, Bhutan and Bangladesh). Within these regions the distribution is highly fragmented and includes a number of small non‐viable isolated populations. The habitat in north‐eastern India is still contiguous with that in Bhutan, Myanmar and Bangladesh and to some extent with Nepal. Although the estimated population of the Gaur is 23 000–34 000, it is declining alarmingly. Populations outside the protected areas may not last long. An action plan has been proposed for its conservation.     

Intraclutch egg-size variation in the Barnacle Goose Branta leucopsis: an egg-removal experiment

We carried out an egg-removal experiment on Barnacle Geese Branta leucopsis to test the hypothesis that tactile contact between the brood patch and eggs accumulating in the nest during laying was causally related to intraclutch egg-size variation, acting through the development of incubation behaviour. Egg removal had no effect on mean egg mass, relaying interval or clutch size: mean (±s.e.) clutch sizes for first clutches were 4.9 ± 0.9 and 4.7 ± 0.9 eggs for control and experimental females, respectively. We therefore conclude that Barnacle Geese have a determinate pattern of egg laying. Daily removal of all eggs from the first-laid egg did not affect the within-clutch pattern of egg-size variation: in both control and experimental clutches the first egg was relatively small, the second or third egg was largest and there was a linear decline in egg size to the smallest, last-laid egg. There was no significant difference in either the absolute or relative size of the last-laid eggs in control and experimental clutches. Tactile contact with eggs in the nest, therefore, is not required for the expression of intraclutch egg-size variation in Barnacle Geese. In this respect, determinate-laying Barnacle Geese differ from species with indeterminate laying patterns (e.g. gulls) where egg removal does affect the normal pattern of within-clutch egg-size variation. If hormonal changes (e.g. prolactin) associated with onset of incubation are causally related to the intraclutch decrease in egg size, then the stimuli involved appear to differ between determinate and indeterminate layers.     

Recovery of loss in chlorophyll and 2,6-dichlorophenol indophenol Hill reaction of isolated chloroplasts during dark induced aging of intact maize seedlings

Loss in the content of pigments and decline in the efficiency of thylakoid membranes to reduce 2,6-dichlorophenol indophenol (DCPIP) have been investigated during dark induced senescence of attached leaves of maize seedlings. The chlorophyll degradation during senescence is differentially inhibited by indoleacetic acid (IAA), gibberellic acid (GA) and kinetin. IAA and GA behave as mild senescence inhibitors in comparison to kinetin. However, in comparison to light, kinetin is relatively less efficient in counteracting senescence. Dark-induced loss in chlorophyll content is fully recovered by light when the dark incubation period is relatively short. The pattern of light recovery of loss in photoelectron transport during dark-aging is similar to the recovery kinetics of chlorophyll. Continuous kinetin treatment of dark-incubated seedlings inhibits the chlorophyll degradation but with decreased duration of kinetin treatment, the efficiency of the hormone to inhibit chlorophyll loss is reduced. The kinetin-induced inhibition of pigment loss is small in comparison with the effect of light.     

Establishment of the Neural Differentiation Pattern in the Prospective Prosencephalic Ectoderm of the Chick Embryo (Gallus domesticus)

Small graft pieces (size: 0.15 × 0.2 mm to 0.1 × 0.4 mm and 0.25 × 0.25 mm) were isolated from the prospective prosencephalic ectoderm of the definitive primitive streak (st. 4) and head process (st. 5) chick blastoderms, and cultured in vivo intracoelomically. In all 1437 graft pieces isolated from 448 donor blastoderms were transplanted into the coelom of 941 host embryos; 216 hosts died before reaching 12 days. The 725 surviving hosts, which carried 1241 implants, yielded 304 analysable grafts. The very small size of the isolates affected the recovery rate. The histological analysis of the recovered grafts reveals that the frequency of neuralization was higher in the grafts isolated from the central region of the prospective prosencephalic ectoderm than in those from its peripheral region. A centrifugal extension of differentiation tendencies of prosencephalic structures was observed from st. 4 to st. 5. At st. 5 frequency of telencephalic structures was high in the grafts of the anterior region, whereas that of diencephalic structures was high in those of the more posterior region. Eye structures (retina as well as tapetum) differentiated in an area measuring ca. 0.4 × 0.1 mm extending transversely about 0.1 mm anterior to the head process at st. 5. Structural elements of the lens were not observed in any graft.     

Potential of double-cropped rice ecology to conserve organic carbon under subtropical climate

Understanding the processes of soil organic carbon (SOC) accumulation or depletion under different management strategies is vital for maintaining soil health and curbing global warming. Using a 36-year-old fertility experiment under subtropical climate, we investigated the impact of long-term intensive rice–rice cropping system with different managements on the SOC stock. The mechanistic pathway of stabilization of the SOC into different pools, with a tentative C budgeting was also established. Biochemical composition of the organic residues involved, SOC pools of different oxidizability and methane (CH₄) emission were estimated for the experiment conducted using organic and inorganic sources of nutrients. Cultivation over the years caused a net decrease in SOC stocks but with balanced fertilization it increased. With increasing depth, the stock decreased on average, to the extent of 50%, 26% and 24% of the total at 0–0.2, 0.2–0.4 and 0.4–0.6 m, respectively. About 4.0% of the crop residues C incorporated into the soil were stabilized into SOC. This was further enhanced (1.6 times) by the application of compost. Carbon loss through CH₄ emission was very low (2.6% of the total). 'Summer fallow' had a positive significant influence on C loss from the system. As much as 29% of the compost C added to the soil was stabilized into SOC mostly in the less-labile or nonlabile recalcitrant pools preferentially in the surface layer of the soil. Large polyphenol and lignin contents of crop residues including compost, and the long period of soil submergence under rice cultivation might have conferred recalcitrant character to the SOC leading to its stabilization in nonlabile pools. This would result into an enrichment of the SOC stock and restriction to the gaseous C loading into the atmosphere.     

Light versus pheromone-bearing wind in the control of flight direction by bark beetles, Scolytus multistriatus

ABSTRACT. A wind tunnel lit from above was used to measure the relative effectiveness of light as opposed to pheromone-bearing wind in directing the flight of male S.multistriatus. Upward flight in the tunnel was overridingly phototactic not geotactic, while horizontally upwind flight toward the pheromone source was anemotactic not chemotactic, since the pheromone concentration was uniform in the tunnel. The flight tracks of newly-emerged unfed and previously unflown beetles were preponderantly upwards and downwind; the longer the beetles had spent in flight activity beforehand, the more of them flew upwind.