禁牧对锡林郭勒典型草原物种多样性的影响

为了研究禁牧对典型草原物种多样性的影响,对自由放牧和不同时间(1987、1997和2003年)禁牧的典型草原的物种组成进行了调查.结果表明:禁牧并未使典型草原的主要物种组成发生明显的改变,但使物种的相对重要性发生了明显变化,优势种的优势更加明显;同时,禁牧在一定的时间内可以提高典型草原的物种多样性,但随着禁牧时间的延长,典型草原的物种多样性和丰富度都表现出一种先上升后下降的趋势;在相同的禁牧或放牧条件下,水分条件较好的典型草原具有更高的物种多样性.可见,合理的禁牧时间与优越的水分条件有利于典型草原维持较高的物种多样性.典型草原物种多样性下降可能是人为干扰与干旱环境条件共同作用的结果.     

<Emphasis Type="Italic">In vitro</Emphasis> selection and regeneration of chrysanthemum (<Emphasis Type="Italic">Dendranthema grandiflorum</Emphasis> Tzelev) plants resistant to culture filtrate of <Emphasis Type="Italic">Septoria obesa</Emphasis> Syd

Callus cultures derived from leaf segments of chrysanthemum cultivar ‘Snow Ball’ which was susceptible to Septoria obesa were successfully used for in vitro selection for resistance to this pathogenic fungus. Resistant cell lines were selected by culturing callus on growth medium containing various concentrations of S. obesa filtrate. Resistant calluses obtained after two cycles (30 d each cycle) of selection were used for plant regeneration. About 30% of the plants regenerated from the resistant calluses and 70–80% of the plants raised from cuttings had acquired considerable resistance against the pathogen in the field. No phenotypic variation was observed in the selected regenerates.     

Diagnosis of Helicobacter pylori

The different invasive and noninvasive diagnostic tests for Helicobacter pylori have been applied mainly in emerging countries. Molecular methods have been developed, especially a test for detection of H. pylori and its clarithromycin resistance directly from stools. The long-term effects of eradication on histologic lesions have been studied in a meta-analysis and the prognostic value of post-treatment in gastric mucosa-associated lymphoid tissue lymphoma has been assessed. An operating link for gastritis assessment (the OLGA staging) has also been published. Attempts to simplify the urea breath test protocol have been made, and new stool antigen tests have been proposed and compared to those previously available.     

Antibiogram,prevalence of methicillin-resistant and multi-drug resistant Staphylococcus spp. in different clinical samples

Methicillin-resistant Staphylococcus spp. (MRSS) are causing numerous forms of illness in humans ranging from mild to fatal infections. We need to investigate the resistant pattern for different clinical isolates to control the resistance phenomena. This study was designed to provide the resistance pattern of isolated Staphylococcus spp. from various clinical samples in Khartoum State and to elucidate the frequencies of Multidrug-resistant (MDR), Extensively drug-resistant (XDR) and pan-drug resistant (PDR). Two hundred and ten bacterial isolates were from different sources (catheter tip, sputum, vaginal swab, urine, tracheal aspirate, blood, pus, nasal swab, stool, throat swab, pleural fluid, and ear swab). Isolates were identified based on their morphological characters and biochemical reaction. Antibiotics susceptibility screening was performed using twenty-three antibiotics from eighteen classes against all isolated Staphylococcus spp. following the Clinical and Laboratory Standards Institute (CLSI) guideline. The result revealed that out of 63 Gram-positive isolated bacteria, 52 (82.5%) were Staphylococcus spp. with a high incidence of S. aureus 37(71.2%). Out of all Staphylococcus spp., 38 (73.1%) were Methicillin-resistant (MR). The prevalence of MDR was higher in S. aureus (89.2%) than in S. epidermidis (75%). All Staphylococcus spp. displayed resistance to ampicillin and penicillin, while all S. aureus were sensitive to daptomycin and fosfomycin. One isolate was XDR possible PDR, while no PDR was reported in all isolated bacteria. This study provided evidence for the antimicrobial-resistant (AMR) burden in Sudan and highlighted the need for a practical and functional stewardship program to reduce the unreasonable costs of antibiotics.     

In vitro development of bovine secondary follicles in two- and three-dimensional culture systems using vascular endothelial growth factor,insulin-like growth factor-1, and growth hormone

The aim of this study was to evaluate the development and estradiol production of isolated bovine secondary follicles in two-dimensional (2D, experiment 1) and three-dimensional (3D using alginate, experiment 2) long-term culture systems in the absence (control group; only α-MEM⁺) or presence of vascular endothelial growth factor (VEGF), insulin-like growth factor-1, or GH alone, or a combination of all. A total of 363 isolated secondary follicles were cultured individually for 32 days at 38.5 °C in 5% CO₂ in a humidified incubator with addition of medium (5 μL) every other day. In 2D culture system, follicular growth and antrum formation rates were higher (P < 0.05) in VEGF treatment compared with the other treatments. In 3D culture system, only estradiol concentration was greater (P < 0.05) in the GH than in the control group, whereas the other end points were similar (P > 0.05). In summary, this study demonstrated that the benefits of using a certain type of medium supplement depended on the culture system (2D vs. 3D). Vascular endothelial growth factor was an effective supplement for the in vitro culture of bovine secondary follicles when the 2D culture system was used, whereas GH only affected estradiol production using the 3D culture system. This study sheds light on advancements in methodology to facilitate subsequent studies on bovine preantral follicle development.     

Tool-use for catching ants by chimpanzees at Bossou and Monts Nimba,West Africa

The use of tools by wild chimpanzees to catch ants was studied at Bossou and Monts Nimba, south-eastern Guinée. Insect-eating by chimpanzees at Bossou appears to be opportunistic and ant-catching was seen only in certain years. The most common prey species wasDorylus (Dorylus) molestus Gerstaecker. Sixty wands for catching ants were found at Bossou. Half of them were made from Zingiberaceae or Marantaceae, the stems and long petioles of which are usually straight, and have few branches. The length of the wand was variable. The mean length of ant-catching wands (46.7 cm) was between those found at Gombe and Tai. Ants' nests were usually dug up by hand, but on one occasion a digging stick was used. Four chimpanzees who used only one hand to manipulate the wand had also been observed using a stone hammer for nut-cracking. All of them used the same hand in wand-manipulation as in nut-cracking. As reported for chimpanzees at Gombe, Mahale, and Tai, more females than males tended to catch ants with wands though the sex difference was not demonstrated statistically. Ants which climbed up the wand were directly squeezed off using the lower-lip and eaten. This is the same method as seen at Tai, but different from most episodes observed at Gombe. Juveniles and infants also caught ants using wands, however, they seemed to do this more out of curiosity than as a means of feeding. At Goera, over 15 km from Bossou and separated from it by Monts Nimba, the same characteristics of ant-catching techniques were evident from traces.     

Nazarbaev and the north: State‐building and ethnic relations in Kazakhstan

Of all the former Soviet republics, Kazakhstan has what may well be the most untenable interethnic predicament ‐ an ethnic Russian population that is nearly as large as the ethnic Kazakh population. The Russians, moreover, constitute a majority of the population in the northern part of the country, which borders the Russian republic. Having the unenviable task of nation‐building in an increasingly fragmented multi‐ethnic environment, Nazarbaev has made his strategy clear: build a strong unitary Kazakh state by steadily increasing control over the Russian‐dominated provinces of the north. Kazakh action in the north, and Russian response, will determine whether there is a future for a multinational Kazakhstan.