Isolation of gal or bio transducing phage is straightforward because these genes flank the lambda attachment site. For genes located farther away, a simple improper excision event cannot produce transducing phage. Genes located perhaps as far as a minute away on the genetic map, about 40,000 base pairs, from an integrated phage can be picked up by a combination of a deletion of the intervening DNA followed by an improper excision event. In this case the combined probabilities for such a double event are so low that large cell cultures must be used to find the transducing phage. What can be done to isolate phage that carry genes located more than a minute from attB of lambda?

Two approaches were used to bring an integrated phage and a particular gene close enough together to permit generation of transducing phage. Either the gene was moved close to the integrated phage genome or the phage was moved close to the gene. The phage can be brought near the gene by selecting for lysogens following infection of a host deleted of the phage attachment region attB. At very low but usable frequencies, lambda will then integrate into sites that possess some similarity to the normal chromosomal integration site. These secondary integration sites are so widely scattered over the chromosome that lambda can be forced, albeit at very low frequencies, to integrate into or adjacent to most genes. Either the desired integrant can be selected by genetic means or the entire population of cells with phage integrated at many different sites can be used as a source of phage. Some of the phage will excise incorrectly from their abnormal positions and transduce the desired adjacent bacterial genes. The second method of forcing an integrated phage to be near a target gene is to select for the illegitimate recombinational insertion of an episome carrying the gene into a site adjacent to the prophage.

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم الشؤون الفكرية يفتتح الموكب الثقافي العالمي بنسخته التاسعة

بمشاركة قراء العتبة العسكرية المقدسة.. المجمع العلمي ينظم محفلًا قرآنيًّا في سامراء

العتبة العباسية المقدسة تقيم مراسم رفع راية الخدمة الحسينية في مجمّع أبي الفضل العباس (عليه السلام)

قسم الشؤون الدينية يطلق الدورة التأهيلية الأولى للاختبار الديني للمتقدمين للتعيين

المزيد

الآخبار الصحية

"شعور لا مفر منه" في الحياة يهدد حياة الملايين بالموت المبكر!

أعراض للخرف قد تظهر في المشي.. كيف نكتشفها؟

ماذا يحدث لسكر الدم عند شرب القهوة؟

سرطان القلب.. لماذا يعد من أندر أنواع السرطانات؟

المزيد

الآخبار التكنلوجية

صهر أردوغان يطلق منصة تواصل جديدة.. تنافس فيسبوك ؟!

غوغل تطلق "مرشد الويب" لتنظيم نتائج البحث بالذكاء الاصطناعي

بعد 20 عاما.. رصد أصغر أفعى في العالم مجددا في بربادوس !

ذكر أم أنثى؟.. دراسة تنسف الاعتقاد الشائع حول جنس المولود

المزيد

مواضيع ذات صلة

The Double att Phage, att2

Incorrect Excision and gal and bio Transducing Phage

Isolation of Excision-Deficient Mutants

Amplification Techniques in Molecular Biology

Characteristics of Nucleic Acids

solation of Integration-Defective Mutants

Gene Order Permutation and the Campbell Model

Simultaneous Deletion of Chromosomal and Lambda DNA

Mapping Integrated Lambda

Expression Patterns of Developmental Genes

Enhancer Traps for Detecting and Cloning Developmental Genes

Cloning Developmental Genes