我沒見過的外婆

 

 我從來沒見過外婆. 外婆長的什麽樣全靠自己的想象， 或從母親和舅舅的回憶及描述中稍微了解一點她的身世和模樣. 在我想象中她身高一米六上下, 圓臉, 雙眼皮，一頭烏黑的長頭發, 性情溫和, 眼神有點擾鬱。 

 外婆年輕時長得很漂亮，是附近幾個村的佳麗，但她出身貧苦，雖有自己的意中人，還是嫁給外公做了填房。當時（大至在1930年代）家境逐漸衰落, 雖有十來畝地, 外加四十多畝竹林地, 生活也將將過得去, 不算貧困, 但也不富裕.  外婆婚後育有兩女一丁, 我姨媽是長女, 舅舅老二, 我母親末小. 我母親和姨媽在農忙時都要下地幹活, 放牛割草都是份內活. 外公比較重男輕女, 舍得化錢供舅舅念書 (解放後考上醫科大學成為外科醫生). 舅舅不用幹農活. 姨媽是老大, 幹活最多, 所以沒念多少書. 我母親一直念到初中, 畢業後失去經濟來源選擇報考農校(中專), 農校畢業後參加工作, 以農技員/農技師職務長年工作在基層(縣, 區, 社都幹過). 母親一直敬佩她的大姐, 到至今還時不時地給她寄錢. 可謂是姐妹情深。 聽舅舅說, 外公不太顧家, 家裏全靠外婆操勞. 也許是勞累過度, 或是心情擾鬱, 嫁入殷實人家並沒有給她帶來很多快樂，年紀輕輕四十歲不到就病逝了。以前的農家女子真可憐，不會生兒育女會被公婆/老公休了；生的多了又要自己盡力撫養， 耗盡力氣。

 外婆生的兩女一兒，他們又育有九個兒女。重外孫(女)輩又有十幾號，  在北美重外孫就 有六個。如果不是外婆生養了我母親，我不知道今生今世在哪兒。明年回國時定要回外婆老家祖墳上給她燒上幾枝香，再燒好多金元寶 (鄉村習俗, 金元寶是陰間流動貨幣)。

 在這感恩節裏，草寫小文，以表示我對早逝的外婆感恩之心。

 

科普附文：線粒體DNA是以母係遺傳 (Human mitochondriaare normally inherited exclusively from the mother) . 線粒體合成 ATP, 給身體提供能量. 所以從生物化學的角度, 父親隻是給予資助,母親是能源的最終提供者.

Mitochondrial DNA

From Wikipedia, the free encyclopedia

MitochondrialDNA (mtDNA) is the DNA located in organelles called mitochondria,structures within eukaryotic cells that convert the chemical energy fromfood into a form that cells can use, ATP. Most other DNA present in eukaryoticorganisms is found in the cell nucleus.

Mitochondrialinheritance

In most multicellularorganisms, mtDNA is inherited from the mother (maternally inherited).Mechanisms for this include simple dilution (an egg contains 100,000 to1,000,000 mtDNA molecules, whereas a sperm contains only100 to 1000), degradation of sperm mtDNA in the fertilized egg, and, at leastin a few organisms, failure of sperm mtDNA to enter the egg. Whatever themechanism, this single parent (uniparental) pattern of mtDNA inheritance isfound in most animals, most plants and in fungi as well.

Female inheritance

In sexual reproduction, mitochondria are normallyinherited exclusively from the mother. The mitochondria in mammalian sperm areusually destroyed by the egg cell after fertilization. Also, most mitochondriaare present at the base of the sperm's tail, which is used for propelling thesperm cells. Sometimes the tail is lost during fertilization. In 1999 it wasreported that paternal sperm mitochondria (containing mtDNA) are marked with ubiquitin toselect them for later destruction inside the embryo.^[4]Some invitro fertilization techniques, particularly injecting a sperm into an oocyte, mayinterfere with this.

The fact that mitochondrial DNA ismaternally inherited enables researchers to trace maternallineage far back in time. (Ychromosomal DNA, paternally inherited, is used in an analogous way to tracethe agnatelineage.) This is accomplished in humans by sequencing one or more of the hypervariable control regions (HVR1 orHVR2) of the mitochondrial DNA, as with a genealogical DNA test. HVR1 consists of about440 base pairs. These 440 base pairs are then compared to the control regionsof other individuals (either specific people or subjects in a database) todetermine maternal lineage. Most often, the comparison is made to the revised Cambridge Reference Sequence. Vilà etal. have published studies tracing the matrilineal descent of domestic dogsto wolves.^[5]The concept of the Mitochondrial Eve is based on the same type ofanalysis, attempting to discover the origin of humanity by trackingthe lineage back in time.

Because mtDNA is not highlyconserved and has a rapid mutation rate, it is useful for studying theevolutionary relationships - phylogeny - of organisms. Biologists can determine and thencompare mtDNA sequences among different species and use the comparisons tobuild an evolutionary tree for the species examined.

Because mtDNA is transmitted frommother to child (both male and female), it can be a useful tool in genealogicalresearch into a person's maternal line.