东北虎困境何在?

虎是兽中之王,东北虎是虎中之王。然而这王中之王在地球上的命运已经岌岌可危,令人担忧。它们在中国的状况又是如何？抢救它们的行动在积极进行,同时又遇到尴尬……在我们编辑此刊时,几乎无法找到现存的中国野外的东北虎照片,只能在虎园里欣赏它们还保留几分威猛的身影。     

专家诊断东北虎

东北虎在我国已是凤毛麟角。于是,家虎野化被一些媒体称作“拯救东北虎”,一时成为热门话题。然而,当我们就这个问题采访专家的时候,他们马上指出,东北虎与华南虎不同,还没有危机到需要人工繁殖野化的地步。虎的野化是一个极为复杂的过程,现在有一些所谓的“野化”只是商业表演。那么使东北虎重归故里的关键又在哪里呢？     

Ecological evolution of Western Siberian hydrophytobiota

The history of hydrophytobiota development has been traced depending on its adaptation to the ecological conditions in the Palaeogene and Neogene of Western Siberia (WS). A geochronological list of the fossil species of aquatic flora is presented and a classification of relic elements is made.     

Induction of androgenic cultures in Siberian larch

Male generative buds of the Siberian larch have no organic quiescence during the autumn-winter period and are capable of completing the development of male generative structures under favorable conditions. When microsporophylls of the Siberian larch were cultivated on medium MS with 0.2 mg/1 2.4-D, embryoids of two types were obtained: directly from the microspore body and via formation of organogenic callus. This means that in the Siberian larch, direct and indirect androgenesis in vitro is possible. The Siberian larch pollen was first germinated in vitro, which was enhanced by pretreatment with hydrogen peroxide.     

Biologic rhythms derived from Siberian mammoths' hairs

Hair is preserved for millennia in permafrost; it enshrines a record of biologic rhythms and offers a glimpse at chronobiology as it was in extinct animals. Here we compare biologic rhythms gleaned from mammoth's hairs with those of modern human hair. Four mammoths' hairs came from varying locations in Siberia 4600 km, four time zones, apart ranging in age between 18,000 and 20,000 years before present. We used two contemporaneous human hairs for comparison. Power spectra derived from hydrogen isotope ratios along the length of the hairs gave insight into biologic rhythms, which were different in the mammoths depending on location and differed from humans. Hair growth for mammoths was ～31 cms/year and ～16 cms/year for humans. Recurrent annual rhythms of slow and fast growth varying from 3.4 weeks/cycles to 8.7 weeks/cycles for slow periods and 1.2 weeks/cycles to 2.2 weeks/cycles for fast periods were identified in mammoth's hairs. The mineral content of mammoth's hairs was measured by electron microprobe analysis (k-ratios), which showed no differences in sulfur amongst the mammoth hairs but significantly more iron then in human hair. The fractal nature of the data derived from the hairs became evident in Mandelbrot sets derived from hydrogen isotope ratios, mineral content and geographic location. Confocal microscopy and scanning electron microscopy showed varied degrees of preservation of the cuticle largely independent of age but not location of the specimens. X-ray fluorescence microprobe and fluorescence computed micro-tomography analyses allowed evaluation of metal distribution and visualization of hollow tubes in the mammoth's hairs. Seasonal variations in iron and copper content combined with spectral analyses gave insights into variation in food intake of the animals. Biologic rhythms gleaned from power spectral plots obtained by modern methods revealed life style and behavior of extinct mega-fauna.     

Nepotistic vigilance behavior in Siberian jay parents

Many Siberian jay offspring (up to 50%) postpone independenceand stay with their parents for up to 3 years. Parents offersuch nondispersers a benefit in that they increase their vigilancewhile feeding together with retained offspring. In contrast,parents reduce their vigilance while in company of nonrelatedflock members according to the "many eyes" principle. The preferentialtreatment offered by the parents provides an incentive for offspringto forego dispersal. Given evidence for mortality via surpriseattacks by predators (goshawks), such nepotistic vigilance byparents could have a bearing on offspring survival and therebypromote delayed dispersal.     

Community structure of Ephemeroptera in Siberian streams

In recent decades, the relationships between environmental conditions and community structures of stream macroinvertebrates have been investigated in many parts of the world. However, knowledge about assemblages of mayflies and other stream macroinvertebrates in Siberia (northern Asia) and Asia is limited. In fact, the patterns in mayfly species richness and assemblage structure in relation to environmental parameters have not been previously examined in western Siberia. The aim of the present study was to examine the relationship between Ephemeroptera community structure and physical parameters along a river altitude/longitude gradient in Siberia. The results showed that maximum species richness was at relatively low altitudes, high water temperatures, slow current velocities, medium stream widths, medium‐small substrate particle size, and the presence of macrophytes. The mayfly assemblage was separated using TWINSPAN classification into eight distinct groups, which differed significantly with respect to at least one measured environmental factor. Multivariate ordination (detrended correspondence analysis) revealed that mayfly assemblages are structured by a single dominant gradient of altitude‐related environmental variables; altitude and water temperature were the best predictors. Ordination further revealed that mayfly assemblages are structured by altitude‐related environmental factors at high elevations, whereas in the lowlands these factors are less important.     

In vitro capacitation of Siberian tiger spermatozoa

Three experiments were designed to determine optimum conditions for capacitation of Siberian tiger (Panthera tigris altaica) sperm in vitro using the zona-free hamster egg sperm penetration assay (SPA) as a verification of capacitation. Sperm collected from a 9-year-old captive Siberian tiger were subjected to different in vitro washing conditions, preincubation times, and temperatures to induce capacitation. Sperm were able to penetrate zona-free hamster ova after 2 hours preincubation at 37°C but not at time 0. Preincubation at room temperature was not sufficient to prepare sperm for fertilization. The presence of seminal plasma during the 2-hour, 37°C preincubation did not affect the ability of tiger sperm to penetrate zona-free hamster eggs. The SPA can provide a means for evaluation of in vitro capacitation of Siberian tiger sperm.