抄録 地球環境の温暖化によって,野生動物の繁殖や冬眠行動が大きな影響を受けることは容易に想像できる。しかし,実際に冬眠がどのような環境条件に影響されているのかは不明である。そこで,本研究では,冬眠行動を誘発する環境条件について検討を行った。冬眠する齧歯目として知られているシリアンハムスターをモデルとして用いた。冬眠の誘発にとって,気温の低下と日照時間の短縮は最も重要な要因であると考えられる。そこで,ハムスターを恒暗・低温環境下で飼育したところ,冬眠に入った。一方,これらの条件に加えて,飼料としてヒマワリの種子や高脂肪食を充分に与えたのち,給餌制限を行った場合,自由摂食をさせた個体と比較して,短期間で冬眠状態に入ることが見いだされた。このことは,食物の量と組成も冬眠行動の誘発に深く関連することを示唆するものである。また,これまでの実験結果から,体重の大きい個体ほど冬眠に入りやすいことがわかった。このことは,体内に蓄積された脂肪細胞から分泌されるレプチンなどのホルモンが,冬眠行動と関連する可能性を示唆するものである。これらの結果から,冬眠は,環境温度や日照時間,そして食物といった外部環境の変化と関連することが示唆された。 It is considered that global warming and exposure to endocrine disrupting chemicals can influence reproduction and hibernation of wildlife. However, environmental factors responsible for such behavioral differences are not well recognized. Therefore, in this study we analyzed environmental conditions that are critical for inducing hibernation. Non-seasonal hibernators, Syrian hamsters were used in this study. It has been pointed out that a low environmental temperature is an important factor to induce hibernation. So, hamsters were kept at a cold room. After about two or three months, they hibernated. Next, food restriction under the cold environment was performed. When the hamsters were fed sunflower seeds or high fat food not standard laboratory chow and then food supply was restricted, they efficiently hibernated in a shorter time period compared with those which were given free access to food. This suggests that the quantity and nutritional composition of food can affect hibernating behavior in addition to a low environmental temperature. We noticed that hibernation is more efficiently induced in obese hamsters than in thin ones. This may indicate that hormones derived from adipose tissue including leptin could be related to hibernation. These results suggest that hibernation might be associated with external environmental factors (environmental temperature and food composition). arabic 6 English 57
Marwan Draid(3-2007)

Animals alter their locomotor mechanics to adapt to a loss of limb function. To better understand their compensatory mechanisms, this study evaluated the changes in the fore-aft ground forces to forelimb lameness and tested the hypothesis that dogs unload the affected limb by producing a nose-up pitching moment via the exertion of a net-propulsive force when the lame limb is on the ground. Seven healthy Beagles walked and trotted at steady speed on an instrumented treadmill while horizontal force data were collected before and after a moderate lameness was induced. Peak, mean and summed braking and propulsive forces as well as the duration each force was exerted and the time to reach maximum force were evaluated for both the sound and the lame condition. Compared with the sound condition, a net-propulsive force was produced by the lame diagonal limbs due to a reduced braking force in the affected forelimb and an increased propulsive force in the contralateral hindlimb when the dogs walked and trotted. To regain pitch stability and ensure steady speed for a given locomotor cycle, the dogs produced a net-braking force when the sound diagonal limbs were on the ground by exerting greater braking forces in both limbs during walking and additionally reducing the propulsive force in the hindlimb during trotting. Consistent with the proposed mechanism, dogs maximize their double support phases when walking. Likely associated with the fore-aft force adaptations to lameness are changes in muscle recruitment that potentially result in short- and long-term effects on the limb and trunk muscles. arabic 13 English 78
Jalal Mohamed Abdelhadi(12-2012)

Background and Aim: Foodborne illnesses are a serious challenge to human health and the economic sector. For example, salmonellosis remains a burden in developed and developing nations. Rapid and reliable molecular methods to identify Salmonella strains are essential for minimizing human infection. This study aimed to identify Salmonella spp. in raw milk and dairy products using conventional and molecular techniques and to test the antibiotic susceptibility of the isolated strains. Materials and Methods: One hundred and thirty-one milk and dairy product samples were randomly collected from different localities in Libya. Samples were examined for the presence of Salmonella by conventional culture techniques, including cultivation in Rappaport-Vassiliadis broth and streaking on xylose lysine deoxycholate agar. Identification also used polymerase chain reaction and partial sequencing of 16S rDNA. Twenty-four antibiotics were used for the examination of antimicrobial resistance of Salmonella spp. isolates with the agar disk diffusion method (Kirby–Bauer technique). Multi-antibiotic resistance index and antibiotic resistance index (ARI)for Salmonella enterica isolates were calculated. Results: Twenty-one of 131 samples (16%) were positive for Salmonella spp. recovered from 9 (16%), 2 (11%), 4 (22.2%), and 6 (46%) samples of raw cow milk, fermented raw milk, and fresh locally made soft cheeses, Maasora and Ricotta), respectively. Samples of ice cream, milk powder, and infant formula showed no Salmonella spp. contamination. Only 9 of 21 (42.8%) isolates were confirmed as S. enterica by partial sequence 16S rDNA analysis. All isolates were resistant to amoxycillin, bacitracin, penicillin G, lincomycin, vancomycin, clindamycin,
Salah M. Azwai(5-2022)